Smart Polymers: A Comprehensive Literature Review of Recent Developments and Advancements

Subject Areas : Applied smart materials

Ramin Khajavi ^{1 *}

1 - ) Department of Polymer and Textile Engineering, South Tehran Branch, Islamic Azad University,Tehran, Iran.

Received: 2025-01-06 Accepted : 2025-01-30 Published : 2025-02-23

Keywords: Stimuli-Responsive Materials, Thermoresponsive Polymers, pH-Responsive Polymers, Light-Responsive Polmers, Self-Healing Polymers, Shape Memory Polymers (SMPs), Drug Delivery Systems,

Abstract :

Smart polymers, also known as stimuli-responsive materials, represent a frontier in materials science, distinguished by their ability to undergo significant, often reversible, changes in their physicochemical properties in response to small external triggers. Drawing inspiration from adaptive biological systems, these polymers are at the heart of innovations across numerous scientific and technological domains. This comprehensive review synthesizes recent advancements in the field, systematically classifying smart polymers based on their primary stimuli, including temperature, pH, light, and mechanical forces. For each class, we delve into the fundamental response mechanisms, from the molecular-level hydrophobic-hydrophilic balance and ionization dynamics to macroscopic phenomena like phase transitions and swelling/deswelling. Key synthesis methodologies, advanced characterization techniques, and the structure-property relationships that govern their behavior are discussed in detail. Furthermore, the review highlights the expanding applications of these intelligent materials in high-impact areas such as targeted drug delivery, regenerative medicine, tissue engineering, biosensing, and soft robotics. Finally, we address the current challenges, including the need for enhanced biocompatibility, precise control over response kinetics, and multifunctionality, while outlining future research directions poised to unlock the full potential of smart polymers in creating the next generation of advanced materials.

References:


[1] J. V. Alemán et al., "Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)," Pure and Applied Chemistry, vol. 79, no. 10, pp. 1801-1829, 2007/01/01 2007, doi: 10.1351/pac200779101801.
[2] A. Fattah-alhosseini, R. Chaharmahali, S. Alizad, M. Kaseem, and B. Dikici, "A review of smart polymeric materials: Recent developments and prospects for medicine applications," Hybrid Advances, vol. 5, p. 100178, 2024/04 2024, doi: 10.1016/j.hybadv.2024.100178.
[3] A. K. A. Khalil, Y. H. Teow, M. S. Takriff, A. L. Ahmad, and M. A. Atieh, "Recent developments in stimuli-responsive polymer for emerging applications: A review," Results in Engineering, vol. 25, p. 103900, 2025/03 2025, doi: 10.1016/j.rineng.2024.103900.
[4] G. Kocak, C. Tuncer, and V. Bütün, "pH-Responsive polymers," Polymer Chemistry, vol. 8, no. 1, pp. 144-176, 2017, doi: 10.1039/c6py01872f.
[5] V. Aseyev, H. Tenhu, and F. M. Winnik, "Non-ionic thermoresponsive polymers in water," Advances in Polymer Science, vol. 242, pp. 29-89, 2011, doi: 10.1007/12_2010_57.
[6] J. Seuring and S. Agarwal, "Polymers with upper critical solution temperature in aqueous solution," Macromolecular Rapid Communications, vol. 33, no. 22, pp. 1898-1920, 2012, doi: 10.1002/marc.201200433.
[7] Y. J. Kim and Y. T. Matsunaga, "Thermo-responsive polymers and their application as smart biomaterials," J Mater Chem B, vol. 5, no. 23, pp. 4307-4321, Jun 21 2017, doi: 10.1039/c7tb00157f.
[8] Y. Kotsuchibashi, "Recent advances in multi-temperature-responsive polymeric materials," Polymer Journal, vol. 52, no. 7, pp. 681-689, 2020/03/24 2020, doi: 10.1038/s41428-020-0330-0.
[9] G. Nunziata, M. Nava, E. Lacroce, F. Pizzetti, and F. Rossi, "Thermo-Responsive Polymer-Based Nanoparticles: From Chemical Design to Advanced Applications," Macromol Rapid Commun, vol. 46, no. 9, p. e2401127, May 2025, doi: 10.1002/marc.202401127.
[10] S. Qiao and H. Wang, "Temperature-responsive polymers: Synthesis, properties, and biomedical applications," Nano Research, vol. 11, no. 10, pp. 5400-5423, 2018-06-21 2018, doi: 10.1007/s12274-018-2121-x.
[11] M. Sponchioni, U. Capasso Palmiero, and D. Moscatelli, "Thermo-responsive polymers: Applications of smart materials in drug delivery and tissue engineering," Mater Sci Eng C Mater Biol Appl, vol. 102, pp. 589-605, Sep 2019, doi: 10.1016/j.msec.2019.04.069.
[12] P. Zarrintaj et al., "Thermo-sensitive polymers in medicine: A review," European Polymer Journal, vol. 117, pp. 402-423, 2019-08-01 2019, doi: 10.1016/j.eurpolymj.2019.05.024.
[13] M. R. Aguilar and J. San Román, "Introduction to Smart Polymers and Their Applications," in Smart Polymers and their Applications, ed: Elsevier, 2019, pp. 1-11.
[14] H. G. Schild, "Poly(N-isopropylacrylamide): Experiment, theory and application," Progress in Polymer Science, vol. 17, no. 2, pp. 163-249, 1992.
[15] I. Idziak, D. Avoce, D. Lessard, D. Gravel, and X. X. Zhu, "Thermosensitivity of aqueous solutions of poly(N,N-diethylacrylamide)," Macromolecules, vol. 32, no. 4, pp. 1260-1263, 1999, doi: 10.1021/ma981171f.
[16] J. F. Lutz, "Polymerization of oligo(ethylene glycol) (meth)acrylates: Toward new generations of smart biocompatible materials," Journal of Polymer Science Part A: Polymer Chemistry, vol. 46, no. 11, pp. 3459-3470, 2008, doi: 10.1002/pola.22706.
[17] R. Hoogenboom and H. Schlaad, "Bioinspired poly(2-oxazoline)s," Polymers (Basel), vol. 3, no. 1, pp. 467-488, 2011, doi: 10.3390/polym3010467.
[18] J. Seuring, F. M. Bayer, K. Huber, and S. Agarwal, "Upper critical solution temperature of poly(N-acryloyl glycinamide) in water: A concealed property," Macromolecules, vol. 45, no. 1, pp. 374-384, 2012, doi: 10.1021/ma202059t.
[19] D. N. Schulz et al., "Phase behaviour and solution properties of sulphobetaine polymers," Polymer, vol. 27, no. 11, pp. 1734-1742, 1986, doi: 10.1016/0032-3861(86)90269-7.
[20] S. Saeki, N. Kuwahara, M. Nakata, and M. Kaneko, "Upper and lower critical solution temperatures in poly(ethylene glycol) solutions," Polymer, vol. 17, no. 8, pp. 685-689, 1976, doi: 10.1016/0032-3861(76)90208-1.
[21] I. Dimitrov, B. Trzebicka, A. H. Müller, A. Dworak, and C. B. Tsvetanov, "Thermosensitive water-soluble copolymers with doubly responsive reversibly interacting entities," Progress in Polymer Science, vol. 32, no. 11, pp. 1275-1343, 2007, doi: 10.1016/j.progpolymsci.2007.07.001.
[22] C. Weber, R. Hoogenboom, and U. S. Schubert, "Temperature responsive bio-compatible polymers based on poly(ethylene oxide) and poly(2-oxazoline)s," Progress in Polymer Science, vol. 37, no. 5, pp. 686-714, 2012-05-01 2012, doi: 10.1016/j.progpolymsci.2011.10.002.
[23] F. D. Jochum and P. Theato, "Temperature- and light-responsive smart polymer materials," Chem Soc Rev, vol. 42, no. 17, pp. 7468-83, Sep 7 2013, doi: 10.1039/c2cs35191a.
[24] A. S. Hoffman, "Applications of thermally reversible polymers and hydrogels in therapeutics and diagnostics," Journal of Controlled Release, vol. 6, no. 1, pp. 297-305, 1987, doi: 10.1016/0168-3659(87)90083-6.
[25] F. Afroze, E. Nies, and H. Berghmans, "Phase transitions in the system poly(N-isopropylacrylamide)/water and swelling behaviour of the corresponding networks," Journal of Molecular Structure, vol. 554, no. 1, pp. 55-68, 2000, doi: 10.1016/S0022-2860(00)00559-7.
[26] Y. Okada and F. Tanaka, "Cooperative hydration, chain collapse, and flat LCST behavior in aqueous poly(N-isopropylacrylamide) solutions," Macromolecules, vol. 38, no. 10, pp. 4465-4471, 2005, doi: 10.1021/ma0502497.
[27] N. T. Southall, K. A. Dill, and A. D. J. Haymet, "A view of the hydrophobic effect," Journal of Physical Chemistry B, vol. 106, no. 3, pp. 521-533, 2002, doi: 10.1021/jp015514e.
[28] C. Wu and X. Wang, "Globule-to-coil transition of a single homopolymer chain in solution," Physical Review Letters, vol. 80, no. 18, pp. 4092-4094, 1998, doi: 10.1103/PhysRevLett.80.4092.
[29] J. F. Lutz, Ö. Akdemir, and A. Hoth, "Point by point comparison of two thermosensitive polymers exhibiting a similar LCST: Is the age of poly(NIPAM) over?," Journal of the American Chemical Society, vol. 128, no. 40, pp. 13046-13047, 2006, doi: 10.1021/ja065324n.
[30] F. A. Plamper, M. Reschel, A. Schmalz, O. Borisov, M. Ballauff, and A. H. Müller, "Tuning the thermoresponsive properties of weak polyelectrolytes: Aqueous solutions of star-shaped and linear poly(N,N-dimethylaminoethyl methacrylate)," Macromolecules, vol. 40, no. 16, pp. 5689-5697, 2007, doi: 10.1021/ma070452x.
[31] S. Fujishige, K. Kubota, and I. Ando, "Phase transition of aqueous solutions of poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide)," Journal of Physical Chemistry, vol. 93, no. 8, pp. 3311-3313, 1989, doi: 10.1021/j100345a085.
[32] H. G. Schild and D. A. Tirrell, "Microcalorimetric detection of lower critical solution temperatures in aqueous polymer solutions," Journal of Physical Chemistry, vol. 94, no. 10, pp. 4352-4356, 1990, doi: 10.1021/j100373a088.
[33] Y. Zhang, S. Furyk, D. E. Bergbreiter, and P. S. Cremer, "Specific ion effects on the water solubility of macromolecules: PNIPAM and the Hofmeister series," Journal of the American Chemical Society, vol. 127, no. 41, pp. 14505-14510, 2005, doi: 10.1021/ja0546424.
[34] M. Meewes, J. Ricka, M. de Silva, R. Nyffenegger, and T. Binkert, "Coil-globule transition of poly(N-isopropylacrylamide): A study of surfactant effects by light scattering," Macromolecules, vol. 24, no. 21, pp. 5811-5816, 1991, doi: 10.1021/ma00021a014.
[35] F. M. Winnik, M. F. Ottaviani, S. H. Bossmann, M. Garcia-Garibay, and N. J. Turro, "Consolvency of poly(N-isopropylacrylamide) in mixed water-methanol solutions: A look at spin-labeled polymers," Macromolecules, vol. 25, no. 22, pp. 6007-6017, 1992, doi: 10.1021/ma00048a023.
[36] P. Zarrintaj et al., "Biopolymeric Sensors," in Functionalized Polymers, ed: CRC Press, 2021, pp. 235-249.
[37] S. Hajebi, A. Abdollahi, H. Roghani-Mamaqani, and M. Salami-Kalajahi, "Temperature-Responsive Poly(N-Isopropylacrylamide) Nanogels: The Role of Hollow Cavities and Different Shell Cross-Linking Densities on Doxorubicin Loading and Release," Langmuir, vol. 36, no. 10, pp. 2683-2694, Mar 17 2020, doi: 10.1021/acs.langmuir.9b03892.
[38] L. E. Bromberg and E. S. Ron, "Temperature-responsive gels and thermogelling polymer matrices for protein and peptide delivery," Advanced Drug Delivery Reviews, vol. 31, no. 3, pp. 197-221, 1998, doi: 10.1016/S0169-409X(97)00121-X.
[39] P. Maharjan, B. W. Woonton, L. E. Bennett, G. W. Smithers, K. DeSilva, and M. T. Hearn, "Novel chromatographic separation—The potential of smart polymers," Innovative Food Science & Emerging Technologies, vol. 9, no. 2, pp. 232-242, 2008, doi: 10.1016/j.ifset.2007.03.028.
[40] A. Richter, G. Paschew, S. Klatt, J. Lienig, K. F. Arndt, and H. J. P. Adler, "Review on hydrogel-based pH sensors and microsensors," Sensors, vol. 8, no. 1, pp. 561-581, 2008, doi: 10.3390/s8010561.
[41] M. Yamato, Y. Akiyama, J. Kobayashi, J. Yang, A. Kikuchi, and T. Okano, "Temperature-responsive cell culture surfaces for regenerative medicine with cell sheet engineering," Progress in Polymer Science, vol. 32, no. 8, pp. 1123-1133, 2007, doi: 10.1016/j.progpolymsci.2007.06.002.
[42] N. A. Shaibie, N. A. Ramli, N. D. F. Mohammad Faizal, T. Srichana, and M. C. I. Mohd Amin, "Poly(N‐isopropylacrylamide)‐Based Polymers: Recent Overview for the Development of Temperature‐Responsive Drug Delivery and Biomedical Applications," Macromolecular Chemistry and Physics, vol. 224, no. 20, 2023/08/15 2023, doi: 10.1002/macp.202300157.
[43] A. K. Teotia, H. Sami, and A. Kumar, "Thermo-responsive polymers," in Switchable and Responsive Surfaces and Materials for Biomedical Applications, ed: Elsevier, 2015, pp. 3-43.
[44] M. S. Akash and K. Rehman, "Recent progress in biomedical applications of Pluronic (PF127): Pharmaceutical perspectives," J Control Release, vol. 209, pp. 120-38, Jul 10 2015, doi: 10.1016/j.jconrel.2015.04.032.
[45] A. Das, A. Babu, S. Chakraborty, J. F. R. Van Guyse, R. Hoogenboom, and S. Maji, "Poly(N‐isopropylacrylamide) and Its Copolymers: A Review on Recent Advances in the Areas of Sensing and Biosensing," Advanced Functional Materials, vol. 34, no. 37, 2024/05/11 2024, doi: 10.1002/adfm.202402432.
[46] A. G.-A. Mirian, D. C.-S. Yadira, Z.-L. Arturo, and L.-C. Angel, "Hydrogels with Thermal Responsiveness," CRC Press , publication_type = article, 2024.
[47] B. S. Forney, C. Baguenard, and C. A. Guymon, "Improved stimuli-response and mechanical properties of nanostructured poly(N-isopropylacrylamide-co-dimethylsiloxane) hydrogels generated through photopolymerization in lyotropic liquid crystal templates," Soft Matter, vol. 9, no. 31, p. 7458, 2013, doi: 10.1039/c3sm50556a.
[48] E. M. Frazar, R. A. Shah, T. D. Dziubla, and J. Z. Hilt, "Multifunctional temperature-responsive polymers as advanced biomaterials and beyond," (in eng), J Appl Polym Sci, vol. 137, no. 25, p. 48770, Jul 5 2020, doi: 10.1002/app.48770.
[49] S. Lanzalaco and E. Armelin, "Poly(N-isopropylacrylamide) and Copolymers: A Review on Recent Progresses in Biomedical Applications," (in eng), Gels, vol. 3, no. 4, p. 36, Oct 4 2017, doi: 10.3390/gels3040036.
[50] K. Nagase, J. Kobayashi, and T. Okano, "Temperature-responsive intelligent interfaces for biomolecular separation and cell sheet engineering," (in eng), J R Soc Interface, vol. 6 Suppl 3, no. Suppl 3, pp. S293-309, Jun 6 2009, doi: 10.1098/rsif.2008.0499.focus.
[51] L. Xu, S. Zhong, Y. Gao, and X. Cui, "Thermo-responsive poly(N-isopropylacrylamide)-hyaluronic acid nano-hydrogel and its multiple applications," Int J Biol Macromol, vol. 194, pp. 811-818, Jan 1 2022, doi: 10.1016/j.ijbiomac.2021.11.133.
[52] X. Xu et al., "Poly(N-isopropylacrylamide)-Based Thermoresponsive Composite Hydrogels for Biomedical Applications," (in eng), Polymers (Basel), vol. 12, no. 3, p. 580, Mar 5 2020, doi: 10.3390/polym12030580.
[53] L. Yang, X. Fan, J. Zhang, and J. Ju, "Preparation and Characterization of Thermoresponsive Poly(N-Isopropylacrylamide) for Cell Culture Applications," (in eng), Polymers (Basel), vol. 12, no. 2, p. 389, Feb 9 2020, doi: 10.3390/polym12020389.
[54] J. Zhu, S. Yuan, J. Wang, Y. Zhang, M. Tian, and B. Van der Bruggen, "Microporous organic polymer-based membranes for ultrafast molecular separations," Progress in Polymer Science, vol. 110, p. 101308, 2020/11 2020, doi: 10.1016/j.progpolymsci.2020.101308.
[55] J. Liu, A. Debuigne, C. Detrembleur, and C. Jerome, "Poly(N-vinylcaprolactam): a thermoresponsive macromolecule with promising future in biomedical field," Adv Healthc Mater, vol. 3, no. 12, pp. 1941-68, Dec 2014, doi: 10.1002/adhm.201400371.
[56] L. Marsili, M. Dal Bo, G. Eisele, I. Donati, F. Berti, and G. Toffoli, "Characterization of Thermoresponsive Poly-N-Vinylcaprolactam Polymers for Biological Applications," (in eng), Polymers (Basel), vol. 13, no. 16, p. 2639, Aug 8 2021, doi: 10.3390/polym13162639.
[57] M. N. Mohammed, K. B. Yusoh, and J. H. B. H. Shariffuddin, "Poly(N-vinyl caprolactam) thermoresponsive polymer in novel drug delivery systems: A review," Materials Express, vol. 8, no. 1, pp. 21-34, 2018/02/01 2018, doi: 10.1166/mex.2018.1406.
[58] M. Fallon, S. Halligan, R. Pezzoli, L. Geever, and C. Higginbotham, "Synthesis and Characterisation of Novel Temperature and pH Sensitive Physically Cross-Linked Poly (N-vinylcaprolactam-co-itaconic Acid) Hydrogels for Drug Delivery," (in eng), Gels, vol. 5, no. 3, p. 41, Aug 29 2019, doi: 10.3390/gels5030041.
[59] F. Farjadian et al., "Temperature and pH-responsive nano-hydrogel drug delivery system based on lysine-modified poly (vinylcaprolactam)," (in eng), Int J Nanomedicine, vol. 14, pp. 6901-6915, 2019, doi: 10.2147/IJN.S214467.
[60] V. Kozlovskaya and E. Kharlampieva, "Self-Assemblies of Thermoresponsive Poly(N-vinylcaprolactam) Polymers for Applications in Biomedical Field," ACS Applied Polymer Materials, vol. 2, no. 1, pp. 26-39, 2019/12/03 2019, doi: 10.1021/acsapm.9b00863.
[61] M. Marudova and T. Yorov, "Chitosan/poly(lactic acid) blends as drug delivery systems," International Journal of Polymeric Materials and Polymeric Biomaterials, vol. 68, no. 1-3, pp. 99-106, 2018/12/31 2018, doi: 10.1080/00914037.2018.1525728.
[62] L. S. Ribeiro, R. L. Sala, T. A. Robeldo, R. C. Borra, and E. R. Camargo, "Injectable Thermosensitive Nanocomposites Based on Poly(N-vinylcaprolactam) and Silica Particles for Localized Release of Hydrophilic and Hydrophobic Drugs," (in eng), Langmuir, vol. 39, no. 6, pp. 2380-2388, Feb 14 2023, doi: 10.1021/acs.langmuir.2c03160.
[63] A. Chilkoti, T. Christensen, and J. A. MacKay, "Stimulus responsive elastin biopolymers: Applications in medicine and biotechnology," (in eng), Curr Opin Chem Biol, vol. 10, no. 6, pp. 652-7, Dec 2006, doi: 10.1016/j.cbpa.2006.10.010.
[64] C. M. Bellingham, K. A. Woodhouse, P. Robson, S. J. Rothstein, and F. W. Keeley, "Self-aggregation characteristics of recombinantly expressed human elastin polypeptides," Biochim Biophys Acta, vol. 1550, no. 1, pp. 6-19, Nov 26 2001, doi: 10.1016/s0167-4838(01)00262-x.
[65] A. Chilkoti, M. R. Dreher, D. E. Meyer, and D. Raucher, "Targeted drug delivery by thermally responsive polymers," Adv Drug Deliv Rev, vol. 54, no. 5, pp. 613-30, Sep 13 2002, doi: 10.1016/s0169-409x(02)00041-8.
[66] Y. Guo, S. Liu, D. Jing, N. Liu, and X. Luo, "The construction of elastin-like polypeptides and their applications in drug delivery system and tissue repair," (in eng), J Nanobiotechnology, vol. 21, no. 1, p. 418, Nov 11 2023, doi: 10.1186/s12951-023-02184-8.
[67] D. E. Meyer and A. Chilkoti, "Genetically encoded synthesis of protein-based polymers with precisely specified molecular weight and sequence by recursive directional ligation: examples from the elastin-like polypeptide system," Biomacromolecules, vol. 3, no. 2, pp. 357-67, Mar-Apr 2002, doi: 10.1021/bm015630n.
[68] D. E. Meyer and A. Chilkoti, "Quantification of the effects of chain length and concentration on the thermal behavior of elastin-like polypeptides," Biomacromolecules, vol. 5, no. 3, pp. 846-51, May-Jun 2004, doi: 10.1021/bm034215n.
[69] J. C. Rodriguez-Cabello, F. J. Arias, M. A. Rodrigo, and A. Girotti, "Elastin-like polypeptides in drug delivery," Adv Drug Deliv Rev, vol. 97, pp. 85-100, Feb 1 2016, doi: 10.1016/j.addr.2015.12.007.
[70] D. W. Urry, "Physical Chemistry of Biological Free Energy Transduction As Demonstrated by Elastic Protein-Based Polymers," The Journal of Physical Chemistry B, vol. 101, no. 51, pp. 11007-11028, 1997/12/01 1997, doi: 10.1021/jp972167t.
[71] J. van Strien, O. Escalona-Rayo, W. Jiskoot, B. Slutter, and A. Kros, "Elastin-like polypeptide-based micelles as a promising platform in nanomedicine," J Control Release, vol. 353, pp. 713-726, Jan 2023, doi: 10.1016/j.jconrel.2022.12.033.
[72] A. K. Varanko, J. C. Su, and A. Chilkoti, "Elastin-Like Polypeptides for Biomedical Applications," Annu Rev Biomed Eng, vol. 22, no. 1, pp. 343-369, Jun 4 2020, doi: 10.1146/annurev-bioeng-092419-061127.
[73] E. S. Ron and L. E. Bromberg, "Temperature-responsive gels and thermogelling polymer matrices for protein and peptide delivery," Adv Drug Deliv Rev, vol. 31, no. 3, pp. 197-221, May 4 1998, doi: 10.1016/s0169-409x(97)00121-x.
[74] S. Chen et al., "Temperature-responsive magnetite/PEO-PPO-PEO block copolymer nanoparticles for controlled drug targeting delivery," Langmuir, vol. 23, no. 25, pp. 12669-76, Dec 4 2007, doi: 10.1021/la702049d.
[75] G. Dumortier, J. L. Grossiord, F. Agnely, and J. C. Chaumeil, "A review of poloxamer 407 pharmaceutical and pharmacological characteristics," Pharm Res, vol. 23, no. 12, pp. 2709-28, Dec 2006, doi: 10.1007/s11095-006-9104-4.
[76] J. D. Jang, C. Do, J. Bang, Y. S. Han, and T. H. Kim, "Self-Assembly of Temperature Sensitive Unilamellar Vesicles by a Blend of Block Copolymers in Aqueous Solution," (in eng), Polymers (Basel), vol. 11, no. 1, p. 63, Jan 4 2019, doi: 10.3390/polym11010063.
[77] A. V. Kabanov, E. V. Batrakova, and V. Y. Alakhov, "Pluronic block copolymers as novel polymer therapeutics for drug and gene delivery," J Control Release, vol. 82, no. 2-3, pp. 189-212, Aug 21 2002, doi: 10.1016/s0168-3659(02)00009-3.
[78] E. Pinon-Segundo, A. Ganem-Quintanar, J. Rafael Garibay-Bermudez, J. Juan Escobar-Chavez, M. Lopez-Cervantes, and D. Quintanar-Guerrero, "Preparation of nanoparticles by solvent displacement using a novel recirculation system," Pharm Dev Technol, vol. 11, no. 4, pp. 493-501, 2006/01 2006, doi: 10.1080/10837450600940824.
[79] A. Sosnik, D. Cohn, J. San Roman, and G. A. Abraham, "Crosslinkable PEO-PPO-PEO-based reverse thermo-responsive gels as potentially injectable materials," J Biomater Sci Polym Ed, vol. 14, no. 3, pp. 227-39, 2003/01 2003, doi: 10.1163/156856203763572680.
[80] M. Li, X. He, Y. Ling, and H. Tang, "Dual thermoresponsive homopolypeptide with LCST-type linkages and UCST-type pendants: Synthesis, characterization, and thermoresponsive properties," Polymer, vol. 132, pp. 264-272, 2017/12 2017, doi: 10.1016/j.polymer.2017.11.016.
[81] G. Vancoillie, D. Frank, and R. Hoogenboom, "Thermoresponsive poly(oligo ethylene glycol acrylates)," Progress in Polymer Science, vol. 39, no. 6, pp. 1074-1095, 2014/06 2014, doi: 10.1016/j.progpolymsci.2014.02.005.
[82] Y. Yuan et al., "Thermoresponsive polymers with LCST transition: synthesis, characterization, and their impact on biomedical frontiers," RSC Applied Polymers, vol. 1, no. 2, pp. 158-189, 2023, doi: 10.1039/d3lp00114h.
[83] S. K. Singh, C. Venugopal, A. A. Adile, and D. Bakhshinyan, "Bmi1 – A Path to Targeting Cancer Stem Cells," European Oncology & Haematology, vol. 13, no. 02, p. 147, 2017, doi: 10.17925/eoh.2017.13.02.147.
[84] R. T. Guntnur, N. Muzzio, M. Morales, and G. Romero, "Phase transition characterization of poly(oligo(ethylene glycol)methyl ether methacrylate) brushes using the quartz crystal microbalance with dissipation," (in eng), Soft Matter, vol. 17, no. 9, pp. 2530-2538, Mar 11 2021, doi: 10.1039/d0sm02169e.
[85] Q. Li, A. P. Constantinou, and T. K. Georgiou, "A library of thermoresponsive PEG‐based methacrylate homopolymers: How do the molar mass and number of ethylene glycol groups affect the cloud point?," Journal of Polymer Science, vol. 59, no. 3, pp. 230-239, 2020/12/28 2020, doi: 10.1002/pol.20200720.
[86] Q. Li, L. Wang, F. Chen, A. P. Constantinou, and T. K. Georgiou, "Thermoresponsive oligo(ethylene glycol) methyl ether methacrylate based copolymers: composition and comonomer effect," Polymer Chemistry, vol. 13, no. 17, pp. 2506-2518, 2022, doi: 10.1039/d1py01688a.
[87] T. Sarwan, P. Kumar, Y. E. Choonara, and V. Pillay, "Hybrid Thermo-Responsive Polymer Systems and Their Biomedical Applications," Frontiers in Materials, vol. 7, 2020/03/31 2020, doi: 10.3389/fmats.2020.00073.
[88] N. M. Smeets, E. Bakaic, M. Patenaude, and T. Hoare, "Injectable and tunable poly(ethylene glycol) analogue hydrogels based on poly(oligoethylene glycol methacrylate)," Chem Commun (Camb), vol. 50, no. 25, pp. 3306-9, Mar 28 2014, doi: 10.1039/c3cc48514e.
[89] N. Sood, A. Bhardwaj, S. Mehta, and A. Mehta, "Stimuli-responsive hydrogels in drug delivery and tissue engineering," Drug Deliv, vol. 23, no. 3, pp. 758-80, 2014/07/21 2016, doi: 10.3109/10717544.2014.940091.
[90] J. O. Zoppe, N. C. Ataman, P. Mocny, J. Wang, J. Moraes, and H. A. Klok, "Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes," Chem Rev, vol. 117, no. 3, pp. 1105-1318, Feb 8 2017, doi: 10.1021/acs.chemrev.6b00314.
[91] Y. Liuxin, W. Faming, R. Pengfei, Z. Tianzhu, and Z. Qianli, "Poly(2-oxazoline)s: synthesis and biomedical applications," Macromolecular Research, vol. 31, pp. 413 - 426 , publication_type = article, 2023.
[92] "Nitrile-Functionalized Poly(2-oxazoline)s as a Versatile Platform for the Development of Polymer Therapeutics," ed: American Chemical Society (ACS).
[93] "Poly(2-oxazoline)-Based Thermoresponsive Stomatocytes," ed: American Chemical Society (ACS).
[94] J. An, X. Liu, P. Linse, A. Dedinaite, F. M. Winnik, and P. M. Claesson, "Tethered poly(2-isopropyl-2-oxazoline) chains: temperature effects on layer structure and interactions probed by AFM experiments and modeling," Langmuir, vol. 31, no. 10, pp. 3039-48, Mar 17 2015, doi: 10.1021/la504653w.
[95] R. Hoogenboom and H. Schlaad, "Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides," Polymer Chemistry, vol. 8, no. 1, pp. 24-40, 2017, doi: 10.1039/c6py01320a.
[96] A. Lusina, T. Nazim, and M. Ceglowski, "Poly(2-oxazoline)s as Stimuli-Responsive Materials for Biomedical Applications: Recent Developments of Polish Scientists," (in eng), Polymers (Basel), vol. 14, no. 19, p. 4176, Oct 5 2022, doi: 10.3390/polym14194176.
[97] P. Mi, "Stimuli-responsive nanocarriers for drug delivery, tumor imaging, therapy and theranostics," (in eng), Theranostics, vol. 10, no. 10, pp. 4557-4588, 2020, doi: 10.7150/thno.38069.
[98] Z. Varanaraja, N. Hollingsworth, R. Green, and C. R. Becer, "Poly(2-alkyl-2-oxazoline)-Based Copolymer Library with a Thermoresponsive Behavior in Dodecane," ACS Applied Polymer Materials, vol. 5, no. 7, pp. 5158-5168, 2023/06/07 2023, doi: 10.1021/acsapm.3c00625.
[99] T. Yue, L. Jiahui, L. Chen, S. Jialin, L. Kang, and Z. Chuanzhuang, "Poly(N-acryloyl glycinamide-co-N-acryloxysuccinimide) Nanoparticles: Tunable Thermo-Responsiveness and Improved Bio-Interfacial Adhesion for Cell Function Regulation.," ACS Applied Materials & Interfaces, vol. 15, pp. 7867 - 7877 , publication_type = article, 2023.
[100] N. Majstorović, M. Zahedtalaban, and S. Agarwal, "Printable Poly(N-acryloyl glycinamide) Nanocomposite Hydrogel Formulations," Polymer Journal, vol. 55, no. 10, pp. 1085-1095, 2023/06/19 2023, doi: 10.1038/s41428-023-00798-1.
[101] J. Seuring, F. M. Bayer, K. Huber, and S. Agarwal, "Upper Critical Solution Temperature of Poly(N-acryloyl glycinamide) in Water: A Concealed Property," Macromolecules, vol. 45, no. 1, pp. 374-384, 2011/12/16 2011, doi: 10.1021/ma202059t.
[102] Y. Tian et al., "Poly(N-acryloyl glycinamide-co-N-acryloxysuccinimide) Nanoparticles: Tunable Thermo-Responsiveness and Improved Bio-Interfacial Adhesion for Cell Function Regulation," ACS Appl Mater Interfaces, vol. 15, no. 6, pp. 7867-7877, Feb 15 2023, doi: 10.1021/acsami.2c22267.
[103] Y. Zhou, M. Ye, H. Zhao, and X. Wang, "3D-printed PNAGA thermosensitive hydrogelbased microrobots: An effective cancer therapy by temperature-triggered drug release," (in eng), Int J Bioprint, vol. 9, no. 3, p. 709, 2023, doi: 10.18063/ijb.709.
[104] K. Abdelrahman, T. Yeit Haan, T. Mohd Sobri, A. Abdul Latif, and A. Muataz Ali, "Recent Developments in Stimuli-Responsive Polymer for Emerging Applications: A Review," Results in engineering, pp. 103900 , publication_type = article, 2025.
[105] S. Li, "Review on development and application of 4D-printing technology in smart textiles," Journal of Engineered Fibers and Fabrics, vol. 18, 2023/01 2023, doi: 10.1177/15589250231177448.
[106] L. Ren et al., "4D printing of shape-adaptive tactile sensor with tunable sensing characteristics," Composites Part B: Engineering, vol. 265, p. 110959, 2023/10 2023, doi: 10.1016/j.compositesb.2023.110959.
[107] Y. O. Waidi, "Recent Advances in 4D-Printed Shape Memory Actuators," Macromol Rapid Commun, vol. 46, no. 10, p. e2401141, May 2025, doi: 10.1002/marc.202401141.
[108] "98% of articles in PMC accessed in one year," ed: Front Matter, 2010.
[109] Q. Chen et al., "Responsive Magnetic Polymer Nanocomposites through Thermal-Induced Structural Reorganization," (in eng), ACS Nano, vol. 19, no. 6, pp. 6165-6179, Feb 18 2025, doi: 10.1021/acsnano.4c14311.
[110] M. S. A. Darwish, M. H. Mostafa, and L. M. Al-Harbi, "Polymeric Nanocomposites for Environmental and Industrial Applications," (in eng), Int J Mol Sci, vol. 23, no. 3, p. 1023, Jan 18 2022, doi: 10.3390/ijms23031023.
[111] L. Klouda and A. G. Mikos, "Thermoresponsive hydrogels in biomedical applications," (in eng), Eur J Pharm Biopharm, vol. 68, no. 1, pp. 34-45, Jan 2008, doi: 10.1016/j.ejpb.2007.02.025.
[112] H. Koide et al., "Engineering Temperature-Responsive Polymer Nanoparticles that Load and Release Paclitaxel, a Low-Molecular-Weight Anticancer Drug," (in eng), ACS Omega, vol. 9, no. 1, pp. 1011-1019, Jan 9 2024, doi: 10.1021/acsomega.3c07226.
[113] A. Rasool, M. Rizwan, A. ur Rehman Qureshi, T. Rasheed, and M. Bilal, "Thermo-responsive functionalized polymeric nanocomposites," in Smart Polymer Nanocomposites, ed: Elsevier, 2023, pp. 219-240.
[114] M. R. Shah, T. Jabri, and M. Khalid, "Temperature-responsive nanocarriers for drug delivery," in Stimuli-Responsive Nanocarriers for Targeted Drug Delivery, ed: Elsevier, 2025, pp. 101-125.
[115] R. Esfand and D. A. Tomalia, "Poly(amidoamine) (PAMAM) dendrimers: from biomimicry to drug delivery and biomedical applications," Drug Discov Today, vol. 6, no. 8, pp. 427-436, Apr 1 2001, doi: 10.1016/s1359-6446(01)01757-3.
[116] I. M. El-Sherbiny, "Enhanced pH-responsive carrier system based on alginate and chemically modified carboxymethyl chitosan for oral delivery of protein drugs: Preparation and in-vitro assessment," Carbohydrate Polymers, vol. 80, no. 4, pp. 1125-1136, 2010/05 2010, doi: 10.1016/j.carbpol.2010.01.034.
[117] Y. Jun, L. Xiao-yun, Y. Jie, L. Lan, and Z. Liusheng, "pH/TEMPERATURE DUAL STIMULI RESPONSIVE MICROGELS BASED ON INTERPENETRATING POLYMER NETWORK STRUCTURE," Acta Polymerica Sinica, vol. 009, pp. 638 - 644 , publication_type = article, 2009.
[118] F. C. S. R. Ana, V. C. Emanuel, A. P. C. João, A. e. S. Francisca, and G. F. Mara, "Double-Stimuli-Responsive (Temperature and pH) Aqueous Biphasic Systems Comprising Ionic Liquids," ACS Sustainable Chemistry & Engineering , publication_type = article, 2023.
[119] S. Dai, P. Ravi, and K. C. Tam, "pH-Responsive polymers: synthesis, properties and applications," Soft Matter, vol. 4, no. 3, pp. 435-449, Feb 21 2008, doi: 10.1039/b714741d.
[120] J. Singh and P. Nayak, "pH‐responsive polymers for drug delivery: Trends and opportunities," Journal of Polymer Science, vol. 61, no. 22, pp. 2828-2850, 2023/08/23 2023, doi: 10.1002/pol.20230403.
[121] S. Jagtar and N. Pallavi, "pH‐responsive polymers for drug delivery: Trends and opportunities," Journal of Polymer Science , publication_type = article, 2023.
[122] P. Bawa, V. Pillay, Y. E. Choonara, and L. C. du Toit, "Stimuli-responsive polymers and their applications in drug delivery," Biomed Mater, vol. 4, no. 2, p. 022001, Apr 2009, doi: 10.1088/1748-6041/4/2/022001.
[123] D. Schmaljohann, "Thermo- and pH-responsive polymers in drug delivery," Advanced Drug Delivery Reviews, vol. 58, no. 15, pp. 1655-1670, 2006.
[124] F. Liu and M. W. Urban, "Recent advances and challenges in designing stimuli-responsive polymers," Progress in Polymer Science, vol. 35, no. 1-2, pp. 3-23, 2010.
[125] S. Kudaibergenov, W. Jaeger, and A. Laschewsky, "Polymeric betaines: Synthesis, characterization, and application," Advances in Polymer Science, vol. 201, pp. 157-224, 2006.
[126] P. Gupta, K. Vermani, and S. Garg, "Hydrogels: From controlled release to pH-responsive drug delivery," Drug Discovery Today, vol. 7, no. 10, pp. 569-579, 2002.
[127] G. Dalei and S. Das, "Polyacrylic acid-based drug delivery systems: A comprehensive review on the state-of-art," Journal of Drug Delivery Science and Technology, vol. 78, p. 103988, 2022/12 2022, doi: 10.1016/j.jddst.2022.103988.
[128] W. J. Kim, E. H. Lee, Y. J. Kwon, S. K. Ye, and K. O. Kim, "Targeted drug release system based on pH-responsive PAA-POSS nanoparticles," (in eng), RSC Adv, vol. 12, no. 28, pp. 18209-18214, Jun 14 2022, doi: 10.1039/d2ra01141g.
[129] J. Kong, S. S. Park, and C. S. Ha, "pH-Sensitive Polyacrylic Acid-Gated Mesoporous Silica Nanocarrier Incorporated with Calcium Ions for Controlled Drug Release," (in eng), Materials (Basel), vol. 15, no. 17, p. 5926, Aug 27 2022, doi: 10.3390/ma15175926.
[130] L. S. Lim, I. Ahmad, and A. Mat Lazim, "pH Sensitive Hydrogel Based on Poly(Acrylic Acid) and Cellulose Nanocrystals," Sains Malaysiana, vol. 44, no. 6, pp. 779-785, 2015/06/01 2015, doi: 10.17576/jsm-2015-4406-02.
[131] E. S. Paker and M. Senel, "Polyelectrolyte Multilayers Composed of Polyethyleneimine-Grafted Chitosan and Polyacrylic Acid for Controlled-Drug-Delivery Applications," (in eng), J Funct Biomater, vol. 13, no. 3, p. 131, Aug 28 2022, doi: 10.3390/jfb13030131.
[132] S. Pavlukhina, Y. Lu, A. Patimetha, M. Libera, and S. Sukhishvili, "Polymer multilayers with pH-triggered release of antibacterial agents," Biomacromolecules, vol. 11, no. 12, pp. 3448-56, Dec 13 2010, doi: 10.1021/bm100975w.
[133] M. Pourmadadi et al., "Polyacrylic acid mediated targeted drug delivery nano-systems: A review," Journal of Drug Delivery Science and Technology, vol. 80, p. 104169, 2023/02 2023, doi: 10.1016/j.jddst.2023.104169.
[134] W. Zhang, X. Hu, F. Jiang, Y. Li, W. Chen, and T. Zhou, "Preparation of bacterial cellulose/acrylic acid-based pH-responsive smart dressings by graft copolymerization method," J Biomater Sci Polym Ed, vol. 35, no. 18, pp. 2767-2789, Dec 2024, doi: 10.1080/09205063.2024.2389689.
[135] D. Sheng, R. Palaniswamy, and T. Kam Chiu, "pH-Responsive polymers: synthesis, properties and applications," Soft Matter, vol. 4, pp. 435 - 449 , publication_type = article, 2008.
[136] P. C. Govind and S. B. Shashwat, "Smart Polymers for Biomedical Applications," vol. 3, pp. 1 , publication_type = article, 2019.
[137] L. Chuanfeng, D. Zhengyu, and R. G. Elizabeth, "Designing polymers with stimuli-responsive degradation for biomedical applications," Current Opinion in Biomedical Engineering, vol. 25, pp. 100437 , publication_type = article, 2022.
[138] "pH-Responsive Rheology and Structure of Poly(ethylene oxide)Poly(methacrylic acid) Interpolymer Complexes," ed: American Chemical Society (ACS).
[139] A. Alsuraifi, A. Curtis, D. A. Lamprou, and C. Hoskins, "Stimuli Responsive Polymeric Systems for Cancer Therapy," (in eng), Pharmaceutics, vol. 10, no. 3, p. 136, Aug 22 2018, doi: 10.3390/pharmaceutics10030136.
[140] D. Ha, N. Yang, and V. Nadithe, "Exosomes as therapeutic drug carriers and delivery vehicles across biological membranes: current perspectives and future challenges," (in eng), Acta Pharm Sin B, vol. 6, no. 4, pp. 287-96, Jul 2016, doi: 10.1016/j.apsb.2016.02.001.
[141] S. Maher, R. J. Mrsny, and D. J. Brayden, "Intestinal permeation enhancers for oral peptide delivery," Adv Drug Deliv Rev, vol. 106, no. Pt B, pp. 277-319, Nov 15 2016, doi: 10.1016/j.addr.2016.06.005.
[142] O. Ozay, "Synthesis and characterization of novel pH‐responsive poly(2‐hydroxylethyl methacrylate‐co‐N‐allylsuccinamic acid) hydrogels for drug delivery," Journal of Applied Polymer Science, vol. 131, no. 1, 2013/08/12 2013, doi: 10.1002/app.39660.
[143] S. Sajeesh and C. P. Sharma, "Novel pH responsive polymethacrylic acid-chitosan-polyethylene glycol nanoparticles for oral peptide delivery," J Biomed Mater Res B Appl Biomater, vol. 76, no. 2, pp. 298-305, Feb 2006, doi: 10.1002/jbm.b.30372.
[144] "Reconstruction of Chitosan Network Orders Using the Meniscus Splitting Method for Designing pH-Responsive Materials," ed: American Chemical Society (ACS).
[145] K. Bal, S. Kucukertugrul Celik, S. Senturk, O. Kaplan, E. B. Eker, and M. K. Gok, "Recent progress in chitosan-based nanoparticles for drug delivery: a review on modifications and therapeutic potential," J Drug Target, pp. 1-28, May 14 2025, doi: 10.1080/1061186X.2025.2502956.
[146] S. Bashir, Y. Y. Teo, S. Naeem, S. Ramesh, and K. Ramesh, "pH responsive N-succinyl chitosan/Poly (acrylamide-co-acrylic acid) hydrogels and in vitro release of 5-fluorouracil," (in eng), PLoS One, vol. 12, no. 7, p. e0179250, 2017, doi: 10.1371/journal.pone.0179250.
[147] H. Hamedi, S. Moradi, S. M. Hudson, A. E. Tonelli, and M. W. King, "Chitosan based bioadhesives for biomedical applications: A review," Carbohydr Polym, vol. 282, p. 119100, Apr 15 2022, doi: 10.1016/j.carbpol.2022.119100.
[148] R. Heras-Mozos, R. Gavara, and P. Hernandez-Munoz, "Chitosan films as pH-responsive sustained release systems of naturally occurring antifungal volatile compounds," Carbohydr Polym, vol. 283, p. 119137, May 1 2022, doi: 10.1016/j.carbpol.2022.119137.
[149] K. M. Huh, H.-M. Pham, C. Joo, M. J. Ferdous, I. Ali, and S.-W. Kang, "Synthesis and Characterization Of N-Octanoyl Glycol Chitosan as a Novel Temperature and Ph-Sensitive Injectable Hydrogel for Biomedical Applications," ed: Elsevier BV, 2025.
[150] S. Kaur and P. Baptista, "Advances in strategies for liver regeneration and replacement," Current Opinion in Biomedical Engineering, vol. 31, p. 100549, 2024/09 2024, doi: 10.1016/j.cobme.2024.100549.
[151] N. Khatibi, M. R. Naimi-Jamal, S. Balalaie, and A. Shokoohmand, "Development and evaluation of a pH-sensitive, naturally crosslinked alginate-chitosan hydrogel for drug delivery applications," Frontiers in Biomaterials Science, vol. 3, 2024/11/01 2024, doi: 10.3389/fbiom.2024.1457540.
[152] P. C. McCarthy, Y. Zhang, and F. Abebe, "Recent Applications of Dual-Stimuli Responsive Chitosan Hydrogel Nanocomposites as Drug Delivery Tools," (in eng), Molecules, vol. 26, no. 16, p. 4735, Aug 5 2021, doi: 10.3390/molecules26164735.
[153] S. Ramezanian, J. Moghaddas, H. Roghani-Mamaqani, and A. Rezamand, "Dual pH- and temperature-responsive poly(dimethylaminoethyl methacrylate)-coated mesoporous silica nanoparticles as a smart drug delivery system," Sci Rep, vol. 13, no. 1, p. 20194, Nov 18 2023, doi: 10.1038/s41598-023-47026-7.
[154] Y.-N. Xu, Z.-Y. Liu, J. Xu, and Y. Cheng, "pH-Responsive Polymer Nanomaterials for Tumor Therapy," Front Chem, vol. 10, p. 876173, 2022, doi: 10.3389/fchem.2022.876173.
[155] P. Pandey et al., "Tumor Microenvironment-Stimuli Responsive Nanoparticles for Anticancer Therapy," Front Bioeng Biotechnol, vol. 8, p. 603701, 2021, doi: 10.3389/fbioe.2020.603701.
[156] J. X. Zhong, J. R. Clegg, E. W. Ander, and N. A. Peppas, "Tunable poly(methacrylic acid-co-acrylamide) nanoparticles through inverse emulsion polymerization," J Biomed Mater Res A, vol. 106, no. 6, pp. 1677-1686, Jun 2018, doi: 10.1002/jbm.a.36371.
[157] B. Jeong and A. Gutowska, "Lessons from nature: Stimuli-responsive polymers and their biomedical applications," Trends in Biotechnology, vol. 20, no. 7, pp. 305-311, 2002.
[158] N. A. Peppas, P. Bures, W. Leobandung, and H. Ichikawa, "Hydrogels in pharmaceutical formulations," European Journal of Pharmaceutics and Biopharmaceutics, vol. 50, no. 1, pp. 27-46, 2000.
[159] L. D. Taylor and L. D. Cerankowski, "Preparation of films exhibiting a balanced temperature dependence to permeation by aqueous solutions—A study of lower consolute behavior," Journal of Polymer Science: Polymer Chemistry Edition, vol. 13, no. 11, pp. 2551-2570, 1975.
[160] X. Yin, A. S. Hoffman, and P. S. Stayton, "Poly(N-isopropylacrylamide-co-propylacrylic acid) copolymers that respond sharply to temperature and pH," Biomacromolecules, vol. 7, no. 5, pp. 1381-1385, 2006.
[161] G. Chen and A. S. Hoffman, "Graft copolymers that exhibit temperature-induced phase transitions over a wide range of pH," Nature, vol. 373, no. 6509, pp. 49-52, 1995.
[162] E. Ruel-Gariépy and J. C. Leroux, "In situ-forming hydrogels—Review of temperature-sensitive systems," European Journal of Pharmaceutics and Biopharmaceutics, vol. 58, no. 2, pp. 409-426, 2004.
[163] M. Wei, Y. Gao, X. Li, and M. J. Serpe, "Stimuli-responsive polymers and their applications," Polymer Chemistry, vol. 8, no. 1, pp. 127-143, 2017.
[164] N. Deirram, C. Zhang, S. S. Kermaniyan, A. P. R. Johnston, and G. K. Such, "pH-responsive polymer nanoparticles for drug delivery," Macromolecular Rapid Communications, vol. 40, no. 10, 2019.
[165] M. Karimi et al., "Temperature-responsive smart nanocarriers for delivery of therapeutic agents: Applications and recent advances," ACS Applied Materials & Interfaces, vol. 8, no. 33, pp. 21107-21133, 2016.
[166] K. S. Soppimath, D. W. Tan, and Y. Y. Yang, "pH-triggered thermally responsive polymer core–shell nanoparticles for drug delivery," Advanced Materials, vol. 17, no. 3, pp. 318-323, 2007.
[167] Z. Y. Qiao, R. Zhang, F. S. Du, D. H. Liang, and Z. C. Li, "Multi-responsive nanogels containing motifs of ortho ester, oligo(ethylene glycol) and disulfide linkage as carriers of hydrophobic anti-cancer drugs," Journal of Controlled Release, vol. 152, no. 1, pp. 57-66, 2011.
[168] S. Thakral, N. K. Thakral, and D. K. Majumdar, "Eudragit: A technology evaluation," Expert Opinion on Drug Delivery, vol. 10, no. 1, pp. 131-149, 2013.
[169] J. M. Knipe and N. A. Peppas, "Multi-responsive hydrogels for drug delivery and tissue engineering applications," Regenerative Biomaterials, vol. 1, no. 1, pp. 57-65, 2015.
[170] N. Zhang et al., "Nanocomposite hydrogel incorporating gold nanorods and paclitaxel-loaded chitosan micelles for combination photothermal-chemotherapy," International Journal of Pharmaceutics, vol. 497, no. 1-2, pp. 210-221, 2021.
[171] L. Tang, Y. Yang, T. Bai, and W. Liu, "Robust MeO2MA/vinyl-4,6-diamino-1,3,5-triazine copolymer hydrogels-mediated reverse gene transfection and thermo-induced cell detachment," Biomaterials, vol. 32, no. 34, pp. 7435-7443, 2017.
[172] Y. Li, Y. Wang, G. Huang, and J. Gao, "Cooperativity principles in self-assembled nanomedicine," Chemical Reviews, vol. 118, no. 11, pp. 5359-5391, 2019.
[173] A. Hervault et al., "Doxorubicin loaded dual pH- and thermo-responsive magnetic nanocarrier for combined magnetic hyperthermia and targeted controlled drug delivery applications," Nanoscale, vol. 8, no. 24, pp. 12152-12161, 2016.
[174] L. A. Schneider, A. Korber, S. Grabbe, and J. Dissemond, "Influence of pH on wound-healing: A new perspective for wound-therapy?," Archives of Dermatological Research, vol. 298, no. 9, pp. 413-420, 2007.
[175] G. Power, Z. Moore, and T. O’Connor, "Measurement of pH, exudate composition and temperature in wound healing: A systematic review," Journal of Wound Care, vol. 26, no. 7, pp. 381-397, 2017.
[176] J. Qu, X. Zhao, P. X. Ma, and B. Guo, "Injectable antibacterial conductive hydrogels with dual response to an electric field and pH for localized “smart” drug release," Acta Biomaterialia, vol. 72, pp. 55-69, 2018.
[177] J. Koehler, F. P. Brandl, and A. M. Goepferich, "Hydrogel wound dressings for bioactive treatment of acute and chronic wounds," European Polymer Journal, vol. 100, pp. 1-11, 2018.
[178] B. Jeong, S. W. Kim, and Y. H. Bae, "Thermosensitive sol–gel reversible hydrogels," Advanced Drug Delivery Reviews, vol. 64, pp. 154-162, 2012.
[179] L. Klouda, "Thermoresponsive hydrogels in biomedical applications: A seven-year update," European Journal of Pharmaceutics and Biopharmaceutics, vol. 97, pp. 338-349, 2015.
[180] K. L. Spiller, S. A. Maher, and A. M. Lowman, "Hydrogels for the repair of articular cartilage defects," Tissue Engineering Part B: Reviews, vol. 17, no. 4, pp. 281-299, 2011.
[181] L. Wang et al., "Visual in vivo degradation of injectable hydrogel by real-time and non-invasive tracking using carbon nanodots as fluorescent indicator," Biomaterials, vol. 145, pp. 192-206, 2020.
[182] H. Wang, S. C. Heilshorn, and Y. Yang, "Adaptable hydrogel networks with reversible linkages for tissue engineering," Advanced Materials, vol. 27, no. 25, pp. 3717-3736, 2018.
[183] D. L. Taylor and M. in het Panhuis, "Self-healing hydrogels," Advanced Materials, vol. 28, no. 41, pp. 9060-9093, 2016.
[184] T. P. Richardson, M. C. Peters, A. B. Ennett, and D. J. Mooney, "Polymeric system for dual growth factor delivery," Nature Biotechnology, vol. 19, no. 11, pp. 1029-1034, 2019.
[185] M. R. Islam and M. J. Serpe, "Polyelectrolyte mediated intra and intermolecular crosslinking in microgel-based etalons for sensing protein concentration in solution," Chemical Communications, vol. 49, no. 33, pp. 2646-2648, 2013.
[186] H. R. Culver, J. R. Clegg, and N. A. Peppas, "Analyte-responsive hydrogels: Intelligent materials for biosensing and drug delivery," Accounts of Chemical Research, vol. 50, no. 2, pp. 170-178, 2017.
[187] V. L. Alexeev et al., "High ionic strength glucose-sensing photonic crystal," Analytical Chemistry, vol. 76, no. 5, pp. 1310-1314, 2004.
[188] J. Zhang, N. A. Peppas, and Y. Lin, "Synthesis and characterization of pH- and temperature-sensitive poly(methacrylic acid)/poly(N-isopropylacrylamide) interpenetrating polymeric networks," Macromolecules, vol. 33, no. 1, pp. 102-107, 2019.
[189] F. Kuralay, S. Demirci, M. Kiristi, L. Oksuz, and A. U. Oksuz, "Poly(3-methylthiophene) thin films deposited electrochemically on platinum electrodes for electrochemical DNA biosensing," Colloids and Surfaces B: Biointerfaces, vol. 123, pp. 685-691, 2016.
[190] X. Liu, Y. Zhao, F. Li, and B. Liu, "Biodegradable polymeric micelles for targeted and pH-responsive drug delivery," Journal of Materials Chemistry B, vol. 8, no. 5, pp. 852-867, 2020.
[191] A. Weltin et al., "Cell culture monitoring for drug screening and cancer research: A transparent, microfluidic, multi-sensor microsystem," Lab on a Chip, vol. 14, no. 1, pp. 138-146, 2014.
[192] S. Frost and M. Ulbricht, "Thermoresponsive ultrafiltration membranes for the switchable permeation and fractionation of nanoparticles," Journal of Membrane Science, vol. 448, pp. 1-11, 2013.
[193] S. Darvishmanesh, J. Degrève, and B. Van der Bruggen, "Mechanisms of solute rejection in solvent resistant nanofiltration: The effect of solvent on solute rejection," Physical Chemistry Chemical Physics, vol. 12, no. 40, pp. 13333-13342, 2011.
[194] T. Xiang, T. Lu, Y. Chen, and W. Zhao, "Effect of coagulation bath conditions on the morphology and performance of PSf membrane blended with a capsaicin-mimic copolymer," Journal of Membrane Science, vol. 520, pp. 120-130, 2017.
[195] D. J. Miller, D. R. Dreyer, C. W. Bielawski, D. R. Paul, and B. D. Freeman, "Surface modification of water purification membranes," Angewandte Chemie International Edition, vol. 56, no. 17, pp. 4662-4711, 2017.
[196] X. Zhu, Y. Su, and Z. Jiang, "A novel dual-layer forward osmosis membrane for protein enrichment and concentration," Separation and Purification Technology, vol. 69, pp. 269-277, 2018.
[197] A. Vanangamudi, M. Patel, J. Patel, and G. Singh, "Synthesis of dual stimuli responsive nanogels by click chemistry," European Polymer Journal, vol. 59, pp. 22-35, 2015.
[198] K. Nagase, M. Yamato, H. Kanazawa, and T. Okano, "Poly(N-isopropylacrylamide)-based thermoresponsive surfaces provide new types of biomedical applications," Biomaterials, vol. 153, pp. 27-48, 2016.
[199] A. Lopez, J. Liu, S. Hong, J. Deng, X. Zhuang, and X. Chen, "Dual pH and temperature responsive helical copolymer libraries," Macromolecules, vol. 50, no. 8, pp. 3430-3438, 2019.
[200] W. Li et al., "Antitumor drug delivery modulated by a polymeric micelle with an upper critical solution temperature," Angewandte Chemie International Edition, vol. 54, no. 10, pp. 3126-3131, 2021.
[201] D. Gao, J. Liu, H. B. Wei, H. F. Li, G. S. Guo, and J. H. Zhang, "A microfluidic approach for anticancer drug analysis based on hydrogel encapsulated tumor cells," Analytica Chimica Acta, vol. 665, no. 1, pp. 7-14, 2020.
[202] N. H. Aloorkar, A. S. Kulkarni, R. A. Patil, and D. J. Ingale, "Star polymers: An overview," International Journal of Pharmaceutical Sciences and Nanotechnology, vol. 5, no. 2, pp. 1675-1684, 2012.
[203] A. S. Hoffman, "Stimuli-responsive polymers: Biomedical applications and challenges for clinical translation," Advanced Drug Delivery Reviews, vol. 65, no. 1, pp. 10-16, 2013.
[204] W. B. Liechty, D. R. Kryscio, B. V. Slaughter, and N. A. Peppas, "Polymers for drug delivery systems," Annual Review of Chemical and Biomolecular Engineering, vol. 1, pp. 149-173, 2010.
[205] P. Schattling, F. D. Jochum, and P. Theato, "Multi-stimuli responsive polymers–the all-in-one talents," Polymer Chemistry, vol. 5, no. 1, pp. 25-36, 2014.
[206] Y. Gao, A. Ahiabu, and M. J. Serpe, "Controlled drug release from the aggregation-disaggregation behavior of pH-responsive microgels," ACS Applied Materials & Interfaces, vol. 6, no. 16, pp. 13749-13756, 2016.
[207] R. Yoshida et al., "Comb-type grafted hydrogels with rapid de-swelling response to temperature changes," Nature, vol. 374, no. 6519, pp. 240-242, 2013.
[208] M. A. C. Stuart et al., "Emerging applications of stimuli-responsive polymer materials," Nature Materials, vol. 9, no. 2, pp. 101-113, 2010.
[209] M. Motornov, Y. Roiter, I. Tokarev, and S. Minko, "Stimuli-responsive nanoparticles, nanogels and capsules for integrated multifunctional intelligent systems," Progress in Polymer Science, vol. 35, no. 1-2, pp. 174-211, 2010.
[210] M. I. Gibson and R. K. O’Reilly, "To aggregate, or not to aggregate? Considerations in the design and application of polymeric thermally-responsive nanoparticles," Chemical Society Reviews, vol. 42, no. 17, pp. 7204-7213, 2013.
[211] D. Roy, W. L. Brooks, and B. S. Sumerlin, "New directions in thermoresponsive polymers," Chemical Society Reviews, vol. 42, no. 17, pp. 7214-7243, 2013.
[212] J. Zhuang, M. R. Gordon, J. Ventura, L. Li, and S. Thayumanavan, "Multi-stimuli responsive macromolecules and their assemblies," Chemical Society Reviews, vol. 42, no. 17, pp. 7421-7435, 2013.
[213] K. Knop, R. Hoogenboom, D. Fischer, and U. S. Schubert, "Poly(ethylene glycol) in drug delivery: Pros and cons as well as potential alternatives," Angewandte Chemie International Edition, vol. 49, no. 36, pp. 6288-6308, 2010.
[214] A. Vashist, A. Vashist, Y. K. Gupta, and S. Ahmad, "Recent advances in hydrogel based drug delivery systems for the human body," Journal of Materials Chemistry B, vol. 2, no. 2, pp. 147-166, 2014.
[215] M. A. Ward and T. K. Georgiou, "Thermoresponsive polymers for biomedical applications," Polymers (Basel), vol. 3, no. 3, pp. 1215-1242, 2011.
[216] J. Chen, M. Liu, H. Liu, and L. Ma, "Synthesis, swelling and drug release behavior of poly(N,N-diethylacrylamide-co-N-hydroxymethyl acrylamide) hydrogel," Materials Science and Engineering: C, vol. 29, no. 7, pp. 2116-2123, 2018.
[217] A. Halperin, M. Kröger, and F. M. Winnik, "Poly(N-isopropylacrylamide) phase diagrams: Fifty years of research," Angewandte Chemie International Edition, vol. 54, no. 51, pp. 15342-15367, 2015.
[218] Q. Zhang, C. Weber, U. S. Schubert, and R. Hoogenboom, "Thermoresponsive polymers with lower critical solution temperature: From fundamental aspects and measuring techniques to recommended turbidimetry conditions," Materials Horizons, vol. 4, no. 2, pp. 109-116, 2015.
[219] D. J. Keddie, "A guide to the synthesis of block copolymers using reversible-addition fragmentation chain transfer (RAFT) polymerization," Chemical Society Reviews, vol. 43, no. 2, pp. 496-505, 2014.
[220] K. Parkatzidis, H. S. Wang, N. P. Truong, and A. Anastasaki, "Recent developments and future challenges in controlled radical polymerization: A 2020 update," Chem, vol. 6, no. 7, pp. 1575-1588, 2020.
[221] M. R. Aguilar and J. San Román, Smart polymers and their applications. Woodhead Publishing, 2014.
[222] A. K. Bajpai, S. K. Shukla, S. Bhanu, and S. Kankane, "Responsive polymers in controlled drug delivery," Progress in Polymer Science, vol. 33, no. 11, pp. 1088-1118, 2008.
[223] S. Schweizerhof, D. E. Demco, A. Mourran, R. Fechete, and M. Möller, "pH-responsive hydrogels based on polyacrylamide and polyacrylic acid semi-interpenetrating polymer networks studied by 1H solid-state NMR spectroscopy," Macromolecular Chemistry and Physics, vol. 218, no. 7, 2017.
[224] M. C. Koetting, J. T. Peters, S. D. Steichen, and N. A. Peppas, "Stimulus-responsive hydrogels: Theory, modern advances, and applications," Materials Science and Engineering: R: Reports, vol. 93, pp. 1-49, 2015.
[225] S. Naahidi, M. Jafari, F. Edalat, K. Raymond, A. Khademhosseini, and P. Chen, "Biocompatibility of engineered nanoparticles for drug delivery," Journal of Controlled Release, vol. 166, no. 2, pp. 182-194, 2013.
[226] M. J. Webber, E. A. Appel, E. W. Meijer, and R. Langer, "Supramolecular biomaterials," Nature Materials, vol. 15, no. 1, pp. 13-26, 2016.
[227] S. Shiguo, "Recent Advances of Multi-Stimuli-Responsive Drug Delivery Systems for Cancer Therapy," vol. 3, 2017.
[228] S. Jing, C. Feng, L. C. Vincent, and B. M. Phillip, "Catechol Polymers for pH-Responsive, Targeted Drug Delivery to Cancer Cells," Journal of the American Chemical Society, vol. 133, pp. 11850 - 11853 , publication_type = article, 2011.
[229] G. Fei, Y. Jianhui, C. Yan, G. Changyong, H. Honggang, and S. Jiacan, "Recent advances in aptamer-based targeted drug delivery systems for cancer therapy," Frontiers in Bioengineering and Biotechnology , publication_type = article, vol. 10, 2022.
[230] C. Shunli, S. Xiaolu, T. Ye, and G. Feng Tao, "pH-Responsive Polymer Nanomaterials for Tumor Therapy," Frontiers in Oncology , publication_type = article, vol. 12, 2022.
[231] S. Dai, P. Ravi, and K. C. Tam, "Stimuli-responsive polymers based on polyglycidyl methacrylate," Soft Matter, vol. 16, no. 7, pp. 1847-1860, 2020.
[232] Z. L. Pianowski, "Recent implementations of molecular photoswitches into smart materials and biological systems," Chemistry - A European Journal, vol. 25, no. 20, pp. 5128-5144, 2019.
[233] O. Bertrand and J. F. Gohy, "Photo-responsive polymers: Synthesis and applications," Polymer Chemistry, vol. 8, no. 1, pp. 52-73, 2017.
[234] Y. Zhang, J. Yu, H. N. Bomba, Y. Zhu, and Z. Gu, "Mechanical force-triggered drug delivery," Chemical Reviews, vol. 116, no. 19, pp. 12536-12563, 2021.
[235] A. Goulet-Hanssens, F. Eisenreich, and S. Hecht, "Enlightening materials with photoswitches," Advanced Materials, vol. 32, no. 20, p. 1905966, 2020.
[236] K. Palczewski, "G protein–coupled receptor rhodopsin," Annual Review of Biochemistry, vol. 75, pp. 743-767, 2006.
[237] O. P. Ernst, D. T. Lodowski, M. Elstner, P. Hegemann, L. S. Brown, and H. Kandori, "Microbial and animal rhodopsins: Structures, functions, and molecular mechanisms," Chemical Reviews, vol. 114, no. 1, pp. 126-163, 2014.
[238] H. Kandori, "Light-driven sodium-pumping rhodopsin: A new concept of active transport," Chemical Reviews, vol. 118, no. 21, pp. 10646-10658, 2015.
[239] Y. Shichida and T. Matsuyama, "Evolution of opsins and phototransduction," Philosophical Transactions of the Royal Society B, vol. 364, no. 1531, pp. 2881-2895, 2009.
[240] A. Terakita, "The opsins," Genome Biology, vol. 6, no. 3, 2005.
[241] N. C. Rockwell, Y. S. Su, and J. C. Lagarias, "Phytochrome structure and signaling mechanisms," Annual Review of Plant Biology, vol. 57, pp. 837-858, 2006.
[242] K. A. Franklin and P. H. Quail, "Phytochrome functions in Arabidopsis development," Journal of Experimental Botany, vol. 61, no. 1, pp. 11-24, 2010.
[243] E. S. Burgie and R. D. Vierstra, "Phytochromes: An atomic perspective on photoactivation and signaling," The Plant Cell, vol. 26, no. 12, pp. 4568-4583, 2014.
[244] M. Chen, J. Chory, and C. Fankhauser, "Light signal transduction in higher plants," Annual Review of Genetics, vol. 38, pp. 87-117, 2004.
[245] J. J. Casal, "Photoreceptor signaling networks in plant responses to shade," Annual Review of Plant Biology, vol. 64, pp. 403-427, 2013.
[246] J. Hughes, "Phytochrome cytoplasmic signaling," Annual Review of Plant Biology, vol. 64, pp. 377-402, 2013.
[247] N. Nelson and C. F. Yocum, "Structure and function of photosystems I and II," Annual Review of Plant Biology, vol. 57, pp. 521-565, 2006.
[248] R. E. Blankenship, Molecular mechanisms of photosynthesis. Wiley-Blackwell, 2014.
[249] R. Croce and H. van Amerongen, "Natural strategies for photosynthetic light harvesting," Nature Chemical Biology, vol. 10, no. 7, pp. 492-501, 2014.
[250] J. Barber, "Photosynthetic energy conversion: Natural and artificial," Chemical Society Reviews, vol. 38, no. 1, pp. 185-196, 2009.
[251] Y. Umena, K. Kawakami, J. R. Shen, and N. Kamiya, "Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 Å," Nature, vol. 473, no. 7345, pp. 55-60, 2011.
[252] J. K. Lanyi, "Bacteriorhodopsin," Annual Review of Physiology, vol. 66, pp. 665-688, 2004.
[253] M. Grote and M. A. O’Malley, "Enlightening the life sciences: The history of halobacterial and microbial rhodopsin research," FEMS Microbiology Reviews, vol. 35, no. 6, pp. 1082-1099, 2011.
[254] K. Inoue et al., "A light-driven sodium ion pump in marine bacteria," Nat Commun, vol. 4, 2013.
[255] J. M. Christie, L. Blackwood, J. Petersen, and S. Sullivan, "Plant flavoprotein photoreceptors," Plant and Cell Physiology, vol. 56, no. 3, pp. 401-413, 2015.
[256] J. Herrou and S. Crosson, "Function, structure and mechanism of bacterial photosensory LOV proteins," Nature Reviews Microbiology, vol. 9, no. 10, pp. 713-723, 2011.
[257] T. E. Swartz et al., "The photocycle of a flavin-binding domain of the blue light photoreceptor phototropin," Journal of Biological Chemistry, vol. 276, no. 39, pp. 36493-36500, 2001.
[258] A. Möglich, R. A. Ayers, and K. Moffat, "Structure and signaling mechanism of Per-ARNT-Sim domains," Structure, vol. 17, no. 10, pp. 1282-1294, 2009.
[259] A. Pudasaini, K. K. El-Arab, and B. D. Zoltowski, "LOV-based optogenetic devices: Light-driven modules to impart photoregulated control of cellular signaling," Frontiers in Molecular Biosciences, vol. 2, 2015.
[260] M. d’Ischia et al., "Melanins and melanogenesis: Methods, standards, protocols," Pigment Cell & Melanoma Research, vol. 26, no. 5, pp. 616-633, 2013.
[261] F. Solano, "Melanins: Skin pigments and much more—types, structural models, biological functions, and formation routes," New Journal of Science, vol. 2014, 2014.
[262] M. Brenner and V. J. Hearing, "The protective role of melanin against UV damage in human skin," Photochemistry and Photobiology, vol. 84, no. 3, pp. 539-549, 2008.
[263] P. Meredith and T. Sarna, "The physical and chemical properties of eumelanin," Pigment Cell Research, vol. 19, no. 6, pp. 572-594, 2006.
[264] B. A. Gilchrest, H. Y. Park, M. S. Eller, and M. Yaar, "Mechanisms of ultraviolet light-induced pigmentation," Photochemistry and Photobiology, vol. 63, no. 1, pp. 1-10, 1996.
[265] F. Rouzaud, A. L. Kadekaro, Z. A. Abdel-Malek, and V. J. Hearing, "MC1R and the response of melanocytes to ultraviolet radiation," Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, vol. 571, no. 1-2, pp. 133-152, 2005.
[266] L. M. Mäthger, E. J. Denton, N. J. Marshall, and R. T. Hanlon, "Mechanisms and behavioural functions of structural coloration in cephalopods," Journal of the Royal Society Interface, vol. 6, no. Suppl 2, pp. S149-S163, 2012.
[267] D. Stuart-Fox and A. Moussalli, "Camouflage, communication and thermoregulation: Lessons from colour changing organisms," Philosophical Transactions of the Royal Society B, vol. 364, no. 1516, pp. 463-470, 2009.
[268] J. Teyssier, S. V. Saenko, D. Van Der Marel, and M. C. Milinkovitch, "Photonic crystals cause active colour change in chameleons," Nat Commun, vol. 6, 2015.
[269] B. Baroli, "Photopolymerization of biomaterials: Issues and potentialities in drug delivery, tissue engineering, and cell encapsulation applications," Journal of Chemical Technology & Biotechnology, vol. 81, no. 4, pp. 491-499, 2006.
[270] K. T. Nguyen, J. L. West, and R. Langer, "Photopolymerizable hydrogels for tissue engineering applications," Biomaterials, vol. 23, no. 22, pp. 4307-4314, 2018.
[271] J. Ralph et al., "Lignins: Natural polymers from oxidative coupling of 4-hydroxyphenyl-propanoids," Phytochemistry Reviews, vol. 3, no. 1-2, pp. 29-60, 2004.
[272] R. Vanholme, B. Demedts, K. Morreel, J. Ralph, and W. Boerjan, "Lignin biosynthesis and structure," Plant Physiology, vol. 153, no. 3, pp. 895-905, 2010.
[273] U. Takahama and T. Oniki, "A peroxidase/phenolics/ascorbate system can scavenge hydrogen peroxide in plant cells," Physiologia Plantarum, vol. 101, no. 4, pp. 845-852, 1997.
[274] A. R. Barceló, "Lignification in plant cell walls," International Review of Cytology, vol. 176, pp. 87-132, 1997.
[275] L. O. Björn, Photobiology: The science of light and life. Springer, 2015.
[276] L. Schmermund et al., "Photo-biocatalysis: Biotransformations in the presence of light," ACS Catalysis, vol. 9, no. 5, pp. 4115-4144, 2019.
[277] T. A. König et al., "Electrically tunable plasmonic behavior of nanocube–polymer nanomaterials induced by a redox-active electrochromic polymer," ACS Nano, vol. 8, no. 6, pp. 6182-6191, 2019.
[278] A. Goulet-Hanssens, F. Eisenreich, and S. Hecht, "Enlightening materials with photoswitches," Advanced Materials, vol. 32, no. 20, 2020.
[279] N. Corrigan, J. Yeow, P. Judzewitsch, J. Xu, and C. Boyer, "Seeing the light: Advancing materials chemistry through photopolymerization," Angewandte Chemie International Edition, vol. 58, no. 16, pp. 5170-5189, 2019.
[280] V. X. Truong, K. Ehrmann, M. Seifermann, P. A. Levkin, and C. Barner-Kowollik, "Wavelength orthogonal photodynamic networks," Chemistry–A European Journal, vol. 28, no. 11, 2022.
[281] K. Jiang, S. Zhang, Y. Wei, Y. Liu, and S. Liu, "Security printing based on stimuli-responsive polymers," Chinese Journal of Polymer Science, vol. 38, no. 3, pp. 213-219, 2020.
[282] F. Zhang, K. A. Timm, K. M. Arndt, and G. A. Woolley, "Photocontrol of coiled-coil proteins in living cells," Angewandte Chemie International Edition, vol. 49, no. 22, pp. 3943-3946, 2021.
[283] J. F. Lutz, M. Ouchi, D. R. Liu, and M. Sawamoto, "Sequence-controlled polymers," Science, vol. 341, no. 6146, 2013.
[284] H. Colquhoun and J. F. Lutz, "Information-containing macromolecules," Nature Chemistry, vol. 6, no. 6, pp. 455-456, 2014.
[285] S. Chatani, C. J. Kloxin, and C. N. Bowman, "The power of light in polymer science: Photochemical processes to manipulate polymer formation, structure, and properties," Polymer Chemistry, vol. 5, no. 7, pp. 2187-2201, 2014.
[286] A. M. Kloxin, A. M. Kasko, C. N. Salinas, and K. S. Anseth, "Photodegradable hydrogels for dynamic tuning of physical and chemical properties," Science, vol. 324, no. 5923, pp. 59-63, 2009.
[287] Y. Yagci, S. Jockusch, and N. J. Turro, "Photoinitiated polymerization: Advances, challenges, and opportunities," Macromolecules, vol. 43, no. 15, pp. 6245-6260, 2010.
[288] S. Dadashi-Silab, S. Doran, and Y. Yagci, "Photoinduced electron transfer reactions for macromolecular syntheses," Chemical Reviews, vol. 116, no. 17, pp. 10212-10275, 2016.
[289] L. Li, J. M. Scheiger, and P. A. Levkin, "Design and applications of photoresponsive hydrogels," Advanced Materials, vol. 31, no. 26, 2019.
[290] E. R. Ruskowitz and C. A. DeForest, "Photoresponsive biomaterials for targeted drug delivery and 4D cell culture," Nature Reviews Materials, vol. 3, no. 2, 2018.
[291] J. Liu and M. W. Urban, "Recent advances and challenges in designing stimuli-responsive polymers," Progress in Polymer Science, vol. 35, no. 1-2, pp. 3-23, 2010.
[292] S. Wang, M. W. Urban, and W. Wang, "Light-responsive polymer materials: Properties and applications," Progress in Materials Science, vol. 128, 2022.
[293] M. Irie, T. Fukaminato, K. Matsuda, and S. Kobatake, "Photochromism of diarylethene molecules and crystals: Memories, switches, and actuators," Chemical Reviews, vol. 114, no. 24, pp. 12174-12277, 2014.
[294] H. Jinming and L. Shiyong, "Responsive Polymers for Detection and Sensing Applications: Current Status and Future Developments," Macromolecules, vol. 43, pp. 8315 - 8330 , publication_type = article, 2010.
[295] M. M. Russew and S. Hecht, "Photoswitches: From molecules to materials," Advanced Materials, vol. 22, no. 31, pp. 3348-3360, 2010.
[296] F. D. Jochum and P. Theato, "Temperature- and light-responsive smart polymer materials," Chemical Society Reviews, vol. 42, no. 17, pp. 7468-7483, 2013.
[297] S. Dolui, B. Sahu, and S. Banerjee, "Stimuli‐Responsive Functional Polymeric Materials: Recent Advances and Future Perspectives," Macromolecular Chemistry and Physics, vol. 226, no. 12, 2025/01/27 2025, doi: 10.1002/macp.202400472.
[298] D. Roy, J. N. Cambre, and B. S. Sumerlin, "Future perspectives and recent advances in stimuli-responsive materials," Progress in Polymer Science, vol. 35, no. 1-2, pp. 278-301, 2010/01 2010, doi: 10.1016/j.progpolymsci.2009.10.008.
[299] N. F. Konig, A. Al Ouahabi, L. Oswald, R. Szweda, L. Charles, and J. F. Lutz, "Photo-editable macromolecular information," (in eng), Nat Commun, vol. 10, no. 1, p. 3774, Sep 4 2019, doi: 10.1038/s41467-019-11566-2.
[300] L. Wang et al., "Visible light-controlled living cationic polymerization of methoxystyrene," (in eng), Nat Commun, vol. 13, no. 1, p. 3621, Jun 24 2022, doi: 10.1038/s41467-022-31359-4.
[301] A. H. Torbati, R. T. Mather, J. E. Reeder, and P. T. Mather, "Fabrication of a light-emitting shape memory polymeric web containing indocyanine green," J Biomed Mater Res B Appl Biomater, vol. 102, no. 6, pp. 1236-43, Aug 2014, doi: 10.1002/jbm.b.33107.
[302] K. M. Herbert, S. Schrettl, S. J. Rowan, and C. Weder, "50th Anniversary Perspective: Solid-State Multistimuli, Multiresponsive Polymeric Materials," Macromolecules, vol. 50, no. 22, pp. 8845-8870, 2017/11/02 2017, doi: 10.1021/acs.macromol.7b01607.
[303] S. Wang, Q. Liu, L. Li, and M. W. Urban, "Recent Advances in Stimuli-Responsive Commodity Polymers," Macromol Rapid Commun, vol. 42, no. 18, p. e2100054, Sep 2021, doi: 10.1002/marc.202100054.
[304] H. M. D. Bandara and S. C. Burdette, "Photoisomerization in different classes of azobenzene," Chemical Society Reviews, vol. 41, no. 5, pp. 1809-1825, 2012.
[305] P. Klán et al., "Photoremovable protecting groups in chemistry and biology: Reaction mechanisms and efficacy," Chemical Reviews, vol. 113, no. 1, pp. 119-191, 2013.
[306] S. R. Trenor, A. R. Shultz, B. J. Love, and T. E. Long, "Coumarins in polymers: From light harvesting to photo-cross-linkable tissue scaffolds," Chemical Reviews, vol. 104, no. 6, pp. 3059-3077, 2004.
[307] N. Corrigan, S. Shanmugam, J. Xu, and C. Boyer, "Photocatalysis in organic and polymer synthesis," Chemical Society Reviews, vol. 48, no. 12, pp. 3365-3424, 2019.
[308] V. V. Jerca, F. A. Jerca, and R. Hoogenboom, "Advances and opportunities in the exciting world of azobenzenes," Nature Reviews Materials, vol. 3, no. 2, p. 18003, 2018.
[309] E. Merino and M. Ribagorda, "Control over molecular motion using the cis-trans photoisomerization of the azo group," Beilstein J Org Chem, vol. 8, pp. 1071-1090, 2012.
[310] R. Klajn, "Spiropyran-based dynamic materials," Chemical Society Reviews, vol. 43, no. 1, pp. 148-184, 2014.
[311] H. Zhao, E. S. Sterner, E. B. Coughlin, and P. Theato, "o-Nitrobenzyl alcohol derivatives: Opportunities in polymer and materials science," Macromolecules, vol. 45, no. 4, pp. 1723-1736, 2012.
[312] P. Klan, A. P. Pelliccioli, T. Pospíšil, and J. Wirz, "2,5-Dimethylphenacyl: A new photoreleasable protecting group for carboxylic acids and alcohols," Photochemical & Photobiological Sciences, vol. 1, no. 11, pp. 920-923, 2006.
[313] T. J. White and D. J. Broer, "Programmable and adaptive mechanics with liquid crystal polymer networks and elastomers," Nature Materials, vol. 14, no. 11, pp. 1087-1098, 2015.
[314] I. Tomatsu, K. Peng, and A. Kros, "Photoresponsive hydrogels for biomedical applications," Advanced Drug Delivery Reviews, vol. 63, no. 14-15, pp. 1257-1266, 2011.
[315] J. García-Amorós and D. Velasco, "Recent advances towards azobenzene-based light-driven real-time information-transmitting materials," Beilstein J Org Chem, vol. 8, pp. 1003-1017, 2012.
[316] L. Kortekaas and W. R. Browne, "The evolution of spiropyran: Fundamentals and progress of an extraordinarily versatile photochrome," Chemical Society Reviews, vol. 48, no. 12, pp. 3406-3424, 2019.
[317] Y. Chen and Z. Guan, "Self-healing polymeric materials using epoxy/mercaptan system," Polymer, vol. 53, no. 9, pp. 1767-1776, 2012.
[318] Y. Zhao, "Photocontrollable block copolymer micelles: What can we control?," J Mater Chem, vol. 19, no. 28, pp. 4887-4895, 2009.
[319] B. Yan, J. C. Boyer, N. R. Branda, and Y. Zhao, "Near-infrared light-triggered dissociation of block copolymer micelles using upconverting nanoparticles," Journal of the American Chemical Society, vol. 133, no. 49, pp. 19714-19717, 2011.
[320] K. Yue, G. Trujillo-de Santiago, M. M. Alvarez, A. Tamayol, N. Annabi, and A. Khademhosseini, "Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels," Biomaterials, vol. 73, pp. 254-271, 2015.
[321] X. Li, J. F. Lovell, J. Yoon, and X. Chen, "Clinical development and potential of photothermal and photodynamic therapies for cancer," Nature Reviews Clinical Oncology, vol. 17, no. 11, pp. 657-674, 2019.
[322] "Correction to DOI: 10.1002/adma.201807920," Adv Mater, vol. 31, no. 21, p. e1901049, May 2019, doi: 10.1002/adma.201901049.
[323] H. M. Bandara and S. C. Burdette, "Photoisomerization in different classes of azobenzene," Chem Soc Rev, vol. 41, no. 5, pp. 1809-25, Mar 7 2012, doi: 10.1039/c1cs15179g.
[324] M. Baroncini, G. Ragazzon, S. Silvi, M. Venturi, and A. Credi, "The eternal youth of azobenzene: new photoactive molecular and supramolecular devices," Pure and Applied Chemistry, vol. 87, no. 6, pp. 537-545, 2015/01/14 2015, doi: 10.1515/pac-2014-0903.
[325] T. Ikeda and O. Tsutsumi, "Optical switching and image storage by means of azobenzene liquid-crystal films," Science, vol. 268, no. 5219, pp. 1873-5, Jun 30 1995, doi: 10.1126/science.268.5219.1873.
[326] G. S. Kumar and D. C. Neckers, "Photochemistry of azobenzene-containing polymers," Chemical Reviews, vol. 89, no. 8, pp. 1915-1925, 1989/12/01 2002, doi: 10.1021/cr00098a012.
[327] A. Natansohn and P. Rochon, "Photoinduced motions in azo-containing polymers," Chem Rev, vol. 102, no. 11, pp. 4139-75, Nov 2002, doi: 10.1021/cr970155y.
[328] G. Wang, X. A. Zhang, L. Kapilevich, and M. Hu, "Recent advances in polymeric microparticle-based drug delivery systems for knee osteoarthritis treatment," (in eng), Front Bioeng Biotechnol, vol. 11, p. 1290870, 2023, doi: 10.3389/fbioe.2023.1290870.
[329] Y. Yu, M. Nakano, and T. Ikeda, "Photomechanics: directed bending of a polymer film by light," Nature, vol. 425, no. 6954, p. 145, Sep 11 2003, doi: 10.1038/425145a.
[330] Y. Zhao, Q. Huang, and Y. Liu, "Recent Advances of Light/Hypoxia-Responsive Azobenzene in Nanomedicine Design," Chembiochem, vol. 25, no. 23, p. e202400635, Dec 2 2024, doi: 10.1002/cbic.202400635.
[331] "Light-Driven Expansion of Spiropyran Hydrogels," ed: American Chemical Society (ACS).
[332] Y. J. Jeong et al., "Light-responsive spiropyran based polymer thin films for use in organic field-effect transistor memories," Journal of Materials Chemistry C, vol. 4, no. 23, pp. 5398-5406, 2016, doi: 10.1039/c6tc00798h.
[333] I. Kathuria and S. Kumar, "Emerging frontiers in spiropyran-driven photoresponsive drug delivery systems and technologies," Dyes and Pigments, vol. 239, p. 112793, 2025/08 2025, doi: 10.1016/j.dyepig.2025.112793.
[334] K. Pandurangan, R. Barrett, D. Diamond, and M. McCaul, "Fluidic Platforms Incorporating Photo-Responsive Soft-Polymers Based on Spiropyran: From Green Synthesis to Precision Flow Control," Frontiers in Materials, vol. 7, 2021/01/22 2021, doi: 10.3389/fmats.2020.615021.
[335] Y. Vidavsky et al., "Enabling Room-Temperature Mechanochromic Activation in a Glassy Polymer: Synthesis and Characterization of Spiropyran Polycarbonate," J Am Chem Soc, vol. 141, no. 25, pp. 10060-10067, Jun 26 2019, doi: 10.1021/jacs.9b04229.
[336] D. Vllasaliu, "Non-Invasive Drug Delivery Systems," (in eng), Pharmaceutics, vol. 13, no. 5, p. 611, Apr 23 2021, doi: 10.3390/pharmaceutics13050611.
[337] M. Abdallah, A. Hijazi, F. Dumur, and J. Lalevee, "Coumarins as Powerful Photosensitizers for the Cationic Polymerization of Epoxy-Silicones under Near-UV and Visible Light and Applications for 3D Printing Technology," (in eng), Molecules, vol. 25, no. 9, p. 2063, Apr 28 2020, doi: 10.3390/molecules25092063.
[338] M. Abdallah, A. Hijazi, J.-T. Lin, B. Graff, F. Dumur, and J. Lalevée, "Coumarin Derivatives as Photoinitiators in Photo-Oxidation and Photo-Reduction Processes and a Kinetic Model for Simulations of the Associated Polymerization Profiles," ACS Applied Polymer Materials, vol. 2, no. 7, pp. 2769-2780, 2020/06/04 2020, doi: 10.1021/acsapm.0c00340.
[339] I. Cazin, E. Rossegger, G. Guedes de la Cruz, T. Griesser, and S. Schlogl, "Recent Advances in Functional Polymers Containing Coumarin Chromophores," (in eng), Polymers (Basel), vol. 13, no. 1, p. 56, Dec 25 2020, doi: 10.3390/polym13010056.
[340] J. M. Cuevas, R. Seoane-Rivero, R. Navarro, and A. Marcos-Fernandez, "Coumarins into Polyurethanes for Smart and Functional Materials," (in eng), Polymers (Basel), vol. 12, no. 3, p. 630, Mar 10 2020, doi: 10.3390/polym12030630.
[341] H. Ghandehari, "ADDR Editor's Collection 2017," Adv Drug Deliv Rev, vol. 122, p. 1, Dec 1 2017, doi: 10.1016/j.addr.2017.11.009.
[342] "Printing Smart Inks of Redox-Responsive Organometallic Polymers on Microelectrode Arrays for Molecular Sensing," ed: American Chemical Society (ACS).
[343] J. Jiang, Q. Chen, M. Xu, J. Chen, and S. Wu, "Photoresponsive Diarylethene-Containing Polymers: Recent Advances and Future Challenges," Macromol Rapid Commun, vol. 44, no. 14, p. e2300117, Jul 2023, doi: 10.1002/marc.202300117.
[344] Q. Luo, H. Cheng, and H. Tian, "Recent progress on photochromic diarylethene polymers," Polymer Chemistry, vol. 2, no. 11, p. 2435, 2011, doi: 10.1039/c1py00167a.
[345] Y. Qin, Y.-T. Wang, H.-B. Yang, and W. Zhu, "Recent advances on the construction of diarylethene-based supramolecular metallacycles and metallacages via coordination-driven self-assembly," Chemical Synthesis, 2021, doi: 10.20517/cs.2021.05.
[346] Z. Zhang et al., "A building-block design for enhanced visible-light switching of diarylethenes," (in eng), Nat Commun, vol. 10, no. 1, p. 4232, Sep 17 2019, doi: 10.1038/s41467-019-12302-6.
[347] J. Zou et al., "Recent Development of Photochromic Polymer Systems: Mechanism, Materials, and Applications," (in eng), Research (Wash D C), vol. 7, p. 0392, 2024, doi: 10.34133/research.0392.
[348] "Photoresponsive Thermoelectric Materials Derived from FullereneC60 PEDOT Hybrid Polymers," ed: American Chemical Society (ACS).
[349] T. Hughes, G. P. Simon, and K. Saito, "Light-Healable Epoxy Polymer Networks via Anthracene Dimer Scission of Diamine Crosslinker," ACS Appl Mater Interfaces, vol. 11, no. 21, pp. 19429-19443, May 29 2019, doi: 10.1021/acsami.9b02521.
[350] F. Li, H. Hou, J. Yin, and X. Jiang, "Multi-Responsive Wrinkling Patterns by the Photoswitchable Supramolecular Network," ACS Macro Letters, vol. 6, no. 8, pp. 848-853, 2017/07/25 2017, doi: 10.1021/acsmacrolett.7b00424.
[351] Y. Li et al., "Combined light- and heat-induced shape memory behavior of anthracene-based epoxy elastomers," (in eng), Sci Rep, vol. 10, no. 1, p. 20214, Nov 19 2020, doi: 10.1038/s41598-020-77246-0.
[352] M. V. Vineeth and M. Jayabalalan, "Polymeric nanocarriers for cancer theranostics," Polymers for Advanced Technologies, vol. 28, pp. 1572 - 1582 , publication_type = article, 2017.
[353] M. C. Chen, M. H. Ling, K. W. Wang, Z. W. Lin, B. H. Lai, and D. H. Chen, "Near-infrared light-responsive composite microneedles for on-demand transdermal drug delivery," Biomacromolecules, vol. 16, no. 5, pp. 1598-607, May 11 2015, doi: 10.1021/acs.biomac.5b00185.
[354] A. Cheref, C. Artigues, and J.-C. Billaut, "A new robust approach for a production scheduling and delivery routing problem**This work was supported by the financial support of the ANR ATHENA project, grant ANR-13- BS02-0006 of the French Agence Nationale de la Recherche," IFAC-PapersOnLine, vol. 49, no. 12, pp. 886-891, 2016, doi: 10.1016/j.ifacol.2016.07.887.
[355] G. Liu, W. Liu, and C.-M. Dong, "UV- and NIR-responsive polymeric nanomedicines for on-demand drug delivery," Polymer Chemistry, vol. 4, no. 12, p. 3431, 2013, doi: 10.1039/c3py21121e.
[356] B. Sana, A. Finne-Wistrand, and D. Pappalardo, "Recent development in near infrared light-responsive polymeric materials for smart drug-delivery systems," Materials Today Chemistry, vol. 25, p. 100963, 2022/09 2022, doi: 10.1016/j.mtchem.2022.100963.
[357] C. P. Shih, X. Tang, C. W. Kuo, D. Y. Chueh, and P. Chen, "Design principles of bioinspired interfaces for biomedical applications in therapeutics and imaging," (in eng), Front Chem, vol. 10, p. 990171, 2022, doi: 10.3389/fchem.2022.990171.
[358] Q. Shou, K. Uto, M. Iwanaga, M. Ebara, and T. Aoyagi, "Near-infrared light-responsive shape-memory poly(ɛ-caprolactone) films that actuate in physiological temperature range," Polymer Journal, vol. 46, no. 8, pp. 492-498, 2014/06/18 2014, doi: 10.1038/pj.2014.48.
[359] Y. Wu, K. Wang, S. Huang, C. Yang, and M. Wang, "Near-Infrared Light-Responsive Semiconductor Polymer Composite Hydrogels: Spatial/Temporal-Controlled Release via a Photothermal "Sponge" Effect," ACS Appl Mater Interfaces, vol. 9, no. 15, pp. 13602-13610, Apr 19 2017, doi: 10.1021/acsami.7b01016.
[360] H. Fu and B. Yu, "3D micro/nano hydrogel structures fabricated by two-photon polymerization for biomedical applications," (in eng), Front Bioeng Biotechnol, vol. 12, p. 1339450, 2024, doi: 10.3389/fbioe.2024.1339450.
[361] Z. Huang, G. Chi-Pong Tsui, Y. Deng, and C.-Y. Tang, "Two-photon polymerization nanolithography technology for fabrication of stimulus-responsive micro/nano-structures for biomedical applications," Nanotechnology Reviews, vol. 9, no. 1, pp. 1118-1136, 2020/01/01 2020, doi: 10.1515/ntrev-2020-0073.
[362] X. Jing, H. Fu, B. Yu, M. Sun, and L. Wang, "Two-photon polymerization for 3D biomedical scaffolds: Overview and updates," (in eng), Front Bioeng Biotechnol, vol. 10, p. 994355, 2022, doi: 10.3389/fbioe.2022.994355.
[363] D. Kehrloesser, P. J. Behrendt, and N. Hampp, "Two-photon absorption triggered drug delivery from a polymer for intraocular lenses in presence of an UV-absorber," Journal of Photochemistry and Photobiology A: Chemistry, vol. 248, pp. 8-14, 2012/11 2012, doi: 10.1016/j.jphotochem.2012.08.012.
[364] S. O'Halloran, A. Pandit, A. Heise, and A. Kellett, "Two-Photon Polymerization: Fundamentals, Materials, and Chemical Modification Strategies," (in eng), Adv Sci (Weinh), vol. 10, no. 7, p. e2204072, Mar 2023, doi: 10.1002/advs.202204072.
[365] S. Ramasundaram, S. Sobha, G. Saravanakumar, and T. H. Oh, "Recent Advances in Biomedical Applications of Polymeric Nanoplatform Assisted with Two-Photon Absorption Process," (in eng), Polymers (Basel), vol. 14, no. 23, p. 5134, Nov 25 2022, doi: 10.3390/polym14235134.
[366] S. Schlie et al., "Three-dimensional cell growth on structures fabricated from ORMOCER by two-photon polymerization technique," J Biomater Appl, vol. 22, no. 3, pp. 275-87, Nov 2007, doi: 10.1177/0885328207077590.
[367] J. Sun, S. Jia, C. Shao, M. R. Dawson, and K. C. Toussaint, "Emerging Technologies for Multiphoton Writing and Reading of Polymeric Architectures for Biomedical Applications," Annu Rev Biomed Eng, vol. 27, no. 1, pp. 129-155, May 2025, doi: 10.1146/annurev-bioeng-110122-015901.
[368] A. Concellón et al., "Light-Responsive Self-Assembled Materials by Supramolecular Post-Functionalization via Hydrogen Bonding of Amphiphilic Block Copolymers," Macromolecules, vol. 49, no. 20, pp. 7825-7836, 2016/10/04 2016, doi: 10.1021/acs.macromol.6b01112.
[369] J. Kim et al., "Light-Responsive Shape- and Color-Changing Block Copolymer Particles with Fast Switching Speed," ACS Nano, vol. 18, no. 11, pp. 8180-8189, Mar 19 2024, doi: 10.1021/acsnano.3c12059.
[370] J. Lee, K. H. Ku, J. Kim, Y. J. Lee, S. G. Jang, and B. J. Kim, "Light-Responsive, Shape-Switchable Block Copolymer Particles," J Am Chem Soc, vol. 141, no. 38, pp. 15348-15355, Sep 25 2019, doi: 10.1021/jacs.9b07755.
[371] J. M. Schumers, C. A. Fustin, and J. F. Gohy, "Light-responsive block copolymers," Macromol Rapid Commun, vol. 31, no. 18, pp. 1588-607, Sep 15 2010, doi: 10.1002/marc.201000108.
[372] B. S. Sumerlin and A. P. Vogt, "Macromolecular Engineering through Click Chemistry and Other Efficient Transformations," Macromolecules, vol. 43, no. 1, pp. 1-13, 2009/11/18 2009, doi: 10.1021/ma901447e.
[373] J. Torres, N. Dhas, M. Longhi, and M. C. Garcia, "Overcoming Biological Barriers With Block Copolymers-Based Self-Assembled Nanocarriers. Recent Advances in Delivery of Anticancer Therapeutics," (in eng), Front Pharmacol, vol. 11, p. 593197, 2020, doi: 10.3389/fphar.2020.593197.
[374] D. Habault, H. Zhang, and Y. Zhao, "Light-triggered self-healing and shape-memory polymers," Chemical Society Reviews, vol. 42, no. 17, pp. 7244-7256, 2013.
[375] T. Ube and T. Ikeda, "Photomobile polymer materials with crosslinked liquid-crystalline structures: Molecular design, fabrication, and functions," Angewandte Chemie International Edition, vol. 53, no. 39, pp. 10290-10299, 2014.
[376] M. Irie, "Diarylethenes for memories and switches," Chemical Reviews, vol. 100, no. 5, pp. 1685-1716, 2000.
[377] S. Wang, Y. Song, and L. Jiang, "Photoresponsive surfaces with controllable wettability," Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 8, no. 1, pp. 18-29, 2018.
[378] X. Qiu, Y. Li, Y. Li, Y. Wu, C. Li, and L. Li, "Light-responsive membranes: Mechanisms, materials, fabrication, and applications," Advanced Materials Interfaces, vol. 6, no. 19, p. 1900435, 2019.
[379] C. Barner-Kowollik et al., "3D laser micro- and nanoprinting: Challenges for chemistry," Angewandte Chemie International Edition, vol. 56, no. 50, pp. 15828-15845, 2017.
[380] G. Chen, H. Qiu, P. N. Prasad, and X. Chen, "Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics," Chemical Reviews, vol. 114, no. 10, pp. 5161-5214, 2020.
[381] L. Dong, Y. Feng, L. Wang, and W. Feng, "Azobenzene-based solar thermal fuels: Design, properties, and applications," Chemical Society Reviews, vol. 48, no. 12, pp. 3519-3536, 2019.
[382] C. Kuttner et al., "Plasmonic library based on substrate-supported gradiential plasmonic arrays," Advanced Optical Materials, vol. 6, no. 18, p. 1800432, 2018.
[383] Z. Q. Cao and G. J. Wang, "Multi-stimuli-responsive polymer materials: Particles, films, and bulk gels," Chemical Record, vol. 16, no. 3, pp. 1398-1435, 2021.
[384] A. Lendlein, H. Jiang, O. Jünger, and R. Langer, "Light-induced shape-memory polymers," Nature, vol. 434, no. 7035, pp. 879-882, 2019.
[385] D. A. Davis et al., "Force-induced activation of covalent bonds in mechanoresponsive polymeric materials," Nature, vol. 459, no. 7243, pp. 68-72, 2020.
[386] L. Florea, D. Diamond, and F. Benito-Lopez, "Photo-responsive polymeric structures based on spiropyran," Macromolecular Materials and Engineering, vol. 304, no. 5, p. 1800549, 2019.
[387] C. Boyer et al., "Copper-mediated living radical polymerization (atom transfer radical polymerization and copper(0) mediated polymerization): From fundamentals to bioapplications," Chemical Reviews, vol. 116, no. 4, pp. 1803-1949, 2016.
[388] J. M. García, F. C. García, F. Serna, and J. L. de la Peña, "High-performance aromatic polyamides," Progress in Polymer Science, vol. 35, no. 5, pp. 623-686, 2021.
[389] A. Abdollahi, H. Roghani-Mamaqani, B. Razavi, and M. Salami-Kalajahi, "Photoluminescent and chromic nanomaterials for anticounterfeiting technologies: Recent advances and future challenges," ACS Nano, vol. 14, no. 11, pp. 14417-14492, 2020.
[390] M. M. Lerch, W. Szymański, and B. L. Feringa, "The (photo)chemistry of stenhouse photoswitches: Guiding principles and system design," Chemical Society Reviews, vol. 47, no. 6, pp. 1910-1937, 2016.
[391] E. R. Ruskowitz and C. A. DeForest, "Photoresponsive biomaterials for targeted drug delivery and 4D cell culture," Nature Reviews Materials, vol. 3, no. 2, p. 17087, 2018.
[392] T. Ikeda, J. I. Mamiya, and Y. Yu, "Photomechanics of liquid-crystalline elastomers and other polymers," Angewandte Chemie International Edition, vol. 46, no. 4, pp. 506-528, 2019.
[393] A. Goulet-Hanssens and C. J. Barrett, "Photo-control of biological systems with azobenzene polymers," Journal of Polymer Science Part A: Polymer Chemistry, vol. 51, no. 14, pp. 3058-3070, 2013.
[394] F. Häse, C. Kreisbeck, and A. Aspuru-Guzik, "Machine learning for quantum dynamics: Deep learning of excitation energy transfer properties," Chemical Science, vol. 8, no. 12, pp. 8419-8426, 2018.
[395] M. Liu et al., "An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets," Nature, vol. 517, no. 7532, pp. 68-72, 2020.
[396] Y. Jiang, J. Wang, Q. Huang, Z. Huang, and W. Huang, "Plasmonic metal nanoparticles for enhanced photochemical reactions," Materials Today, vol. 41, pp. 156-179, 2021.
[397] X. Kuang et al., "Advances in 4D printing: Materials and applications," Advanced Functional Materials, vol. 29, no. 2, p. 1805290, 2019.
[398] D. K. Schneiderman and M. A. Hillmyer, "50th anniversary perspective: There is a great future in sustainable polymers," Macromolecules, vol. 50, no. 10, pp. 3733-3749, 2017.
[399] J. C. Cremaldi and B. Bhushan, "Bioinspired self-healing materials: lessons from nature," (in eng), Beilstein J Nanotechnol, vol. 9, pp. 907-935, 2018, doi: 10.3762/bjnano.9.85.
[400] B. J. Blaiszik et al., "Self-healing polymers and composites," Annual Review of Materials Research, vol. 40, pp. 179-211, 2010, doi: 10.1146/annurev-matsci-070909-104532.
[401] R. P. Wool and K. M. O’Connor, "A theory crack healing in polymers," Journal of Applied Physics, vol. 52, no. 10, pp. 5953-5963, 1981, doi: 10.1063/1.328585.
[402] M. D. Hager, P. Greil, C. Leyens, S. van der Zwaag, and U. S. Schubert, "Self-healing materials," Advanced Materials, vol. 22, no. 47, pp. 5424-5430, 2010, doi: 10.1002/adma.201002334.
[403] S. R. White et al., "Autonomic healing of polymer composites," Nature, vol. 409, no. 6822, pp. 794-797, 2001, doi: 10.1038/35057232.
[404] C. I. Idumah, "Recent advancements in self-healing polymers, polymer blends, and nanocomposites," Polymers and Polymer Composites, vol. 29, no. 4, pp. 246-258, 2020/03/20 2020, doi: 10.1177/0967391120910882.
[405] T. J. Swait et al., "Smart composite materials for self-sensing and self-healing," Plastics, Rubber and Composites, vol. 41, no. 4-5, pp. 215-224, 2012/06 2013, doi: 10.1179/1743289811y.0000000039.
[406] S. Peng, Y. Sun, C. Ma, G. Duan, Z. Liu, and C. Ma, "Recent advances in dynamic covalent bond-based shape memory polymers," e-Polymers, vol. 22, no. 1, pp. 285-300, 2022/01/01 2022, doi: 10.1515/epoly-2022-0032.
[407] Y. Chujo, K. Sada, and T. Saegusa, "Reversible gelation of polyoxazoline by means of Diels-Alder reaction," Macromolecules, vol. 23, no. 10, pp. 2636-2641, 1990/05 2002, doi: 10.1021/ma00212a007.
[408] X. Chen et al., "A thermally re-mendable cross-linked polymeric material," Science, vol. 295, no. 5560, pp. 1698-702, Mar 1 2002, doi: 10.1126/science.1065879.
[409] C. J. Kloxin, T. F. Scott, B. J. Adzima, and C. N. Bowman, "Covalent adaptable networks (CANs): A unique paradigm in cross-linked polymers," Macromolecules, vol. 43, no. 6, pp. 2643-2653, 2010, doi: 10.1021/ma902596s.
[410] P. Cordier, F. Tournilhac, C. Soulié-Ziakovic, and L. Leibler, "Self-healing and thermoreversible rubber from supramolecular assembly," Nature, vol. 451, no. 7181, pp. 977-980, 2008, doi: 10.1038/nature06669.
[411] Y. Yang and M. W. Urban, "Self-healing polymeric materials," Chemical Society Reviews, vol. 42, no. 17, pp. 7446-7467, 2013, doi: 10.1039/c3cs60109a.
[412] P. G. de Gennes, "Reptation of a polymer chain in the presence of fixed obstacles," The Journal of Chemical Physics, vol. 55, no. 2, pp. 572-579, 1971, doi: 10.1063/1.1675789.
[413] J. D. Ferry, Viscoelastic properties of polymers. John Wiley & Sons, 1980.
[414] X. Chen et al., "A thermally re-mendable cross-linked polymeric material," Science, vol. 295, no. 5560, pp. 1698-1702, 2002, doi: 10.1126/science.1065879.
[415] J. Canadell, H. Goossens, and B. Klumperman, "Self-Healing Materials Based on Disulfide Links," Macromolecules, vol. 44, no. 8, pp. 2536-2541, 2011/03/17 2011, doi: 10.1021/ma2001492.
[416] K. Imato and Y. Ooyama, "Stimuli-responsive smart polymers based on functional dyes," Polymer Journal, vol. 56, no. 12, pp. 1093-1109, 2024, doi: 10.1038/s41428-024-00951-4.
[417] R. P. Sijbesma et al., "Reversible polymers formed from self-complementary monomers using quadruple hydrogen bonding," Science, vol. 278, no. 5343, pp. 1601-4, Nov 28 1997, doi: 10.1126/science.278.5343.1601.
[418] M. Burnworth et al., "Optically healable supramolecular polymers," Nature, vol. 472, no. 7343, pp. 334-337, 2011, doi: 10.1038/nature09963.
[419] M. Nakahata, Y. Takashima, H. Yamaguchi, and A. Harada, "Redox-responsive self-healing materials formed from host–guest polymers," Nat Commun, vol. 2, p. 511, 2011, doi: 10.1038/ncomms1521.
[420] R. J. Varley and S. van der Zwaag, "Towards an understanding of thermally activated self-healing of an ionomer system during ballistic penetration," Acta Materialia, vol. 56, no. 19, pp. 5737-5750, 2008, doi: 10.1016/j.actamat.2008.08.008.
[421] S. R. White et al., "Autonomic healing of polymer composites," Nature, vol. 409, no. 6822, pp. 794-7, Feb 15 2001, doi: 10.1038/35057232.
[422] C. J. Hansen, W. Wu, K. S. Toohey, N. R. Sottos, S. R. White, and J. A. Lewis, "Self-healing materials with interpenetrating microvascular networks," Advanced Materials, vol. 21, no. 41, pp. 4143-4147, 2009, doi: 10.1002/adma.200900588.
[423] B. Pang, Y. Yu, and W. Zhang, "Thermoresponsive Polymers Based on Tertiary Amine Moieties," Macromol Rapid Commun, vol. 42, no. 24, p. e2100504, Dec 2021, doi: 10.1002/marc.202100504.
[424] J. D. Rule, E. N. Brown, N. R. Sottos, S. R. White, and J. S. Moore, "Wax-protected catalyst microspheres for efficient self-healing materials," Advanced Materials, vol. 17, no. 2, pp. 205-208, 2005, doi: 10.1002/adma.200400607.
[425] X. Chen, F. Wudl, A. K. Mal, H. Shen, and S. R. Nutt, "New thermally remendable highly cross-linked polymeric materials," Macromolecules, vol. 36, no. 6, pp. 1802-1807, 2003, doi: 10.1021/ma0210675.
[426] B. Ghosh and M. W. Urban, "Self-repairing oxetane-substituted chitosan polyurethane networks," Science, vol. 323, no. 5920, pp. 1458-1460, 2009, doi: 10.1126/science.1167391.
[427] S. D. Bergman and F. Wudl, "Mendable polymers," J Mater Chem, vol. 18, no. 1, pp. 41-62, 2008, doi: 10.1039/B713953P.
[428] P. Froimowicz, H. Frey, and K. Landfester, "Towards the generation of self-healing materials by means of a reversible photo-induced approach," Macromolecular Rapid Communications, vol. 32, no. 5, pp. 468-473, 2011.
[429] A. B. South and L. A. Lyon, "Autonomic self-healing of hydrogel thin films," Angewandte Chemie International Edition, vol. 49, no. 4, pp. 767-770, 2010, doi: 10.1002/anie.200906040.
[430] D. A. Davis et al., "Force-induced activation of covalent bonds in mechanoresponsive polymeric materials," Nature, vol. 459, no. 7243, pp. 68-72, 2009, doi: 10.1038/nature07970.
[431] E. N. Brown, N. R. Sottos, and S. R. White, "Fracture testing of a self-healing polymer composite," Experimental Mechanics, vol. 45, no. 2, pp. 167-177, 2005, doi: 10.1007/BF02427946.
[432] S. J. García, H. R. Fischer, and S. van der Zwaag, "A critical appraisal of the potential of self healing polymeric coatings," Progress in Organic Coatings, vol. 72, no. 3, pp. 211-221, 2011.
[433] C. E. Diesendruck, N. R. Sottos, J. S. Moore, and S. R. White, "Biomimetic self-healing," Angewandte Chemie International Edition, vol. 54, no. 36, pp. 10428-10447, 2015, doi: 10.1002/anie.201500484.
[434] P. A. Pratama, M. Sharifi, A. M. Peterson, and G. R. Palmese, "Room temperature self-healing thermoset based on the Diels–Alder reaction," ACS Applied Materials & Interfaces, vol. 5, no. 23, pp. 12425-12431, 2013, doi: 10.1021/am403459e.
[435] J. M. Matxain, J. M. Asua, and F. Ruipérez, "Design of new disulfide-based organic compounds for the improvement of self-healing materials," Physical Chemistry Chemical Physics, vol. 18, no. 3, pp. 1758-1770, 2016, doi: 10.1039/C5CP06660C.
[436] F. Wang, W. Wang, C. Zhang, J. Tang, X. Zeng, and X. Wan, "Scalable manufactured bio-based polymer nanocomposite with instantaneous near-infrared light-actuated targeted shape memory and remote-controlled accurate self-healing," Composites Part B: Engineering, vol. 219, p. 108927, 2021, doi: 10.1016/j.compositesb.2021.108927.
[437] N. Holten-Andersen et al., "pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli," Proceedings of the National Academy of Sciences, vol. 108, no. 7, pp. 2651-2655, 2011, doi: 10.1073/pnas.1015862108.
[438] M. W. Keller and N. R. Sottos, "Mechanical properties of microcapsules used in a self-healing polymer," Experimental Mechanics, vol. 46, no. 6, pp. 725-733, 2006, doi: 10.1007/s11340-006-9659-3.
[439] Y. Liu and S. H. Hsu, "Synthesis and Biomedical Applications of Self-healing Hydrogels," (in eng), Front Chem, vol. 6, p. 449, 2018, doi: 10.3389/fchem.2018.00449.
[440] Y. Heo, M. H. Malakooti, and H. A. Sodano, "Self-healing polymers and composites for extreme environments," Journal of Materials Chemistry A, vol. 4, no. 44, pp. 17403-17411, 2016, doi: 10.1039/c6ta06213j.
[441] I. C.-Y. Hou, Y. Hu, A. Narita, and K. Müllen, "Diels–Alder polymerization: a versatile synthetic method toward functional polyphenylenes, ladder polymers and graphene nanoribbons," Polymer Journal, vol. 50, no. 1, pp. 3-20, 2017/11/01 2017, doi: 10.1038/pj.2017.69.
[442] Y.-L. Liu and T.-W. Chuo, "Self-healing polymers based on thermally reversible Diels–Alder chemistry," Polymer Chemistry, vol. 4, no. 7, p. 2194, 2013, doi: 10.1039/c2py20957h.
[443] S. M. Morozova, "Recent Advances in Hydrogels via Diels-Alder Crosslinking: Design and Applications," (in eng), Gels, vol. 9, no. 2, p. 102, Jan 24 2023, doi: 10.3390/gels9020102.
[444] C. R. Ratwani, A. R. Kamali, and A. M. Abdelkader, "Self-healing by Diels-Alder cycloaddition in advanced functional polymers: A review," Progress in Materials Science, vol. 131, p. 101001, 2023/01 2023, doi: 10.1016/j.pmatsci.2022.101001.
[445] A. Safaei et al., "Fast Self-Healing at Room Temperature in Diels-Alder Elastomers," (in eng), Polymers (Basel), vol. 15, no. 17, p. 3527, Aug 24 2023, doi: 10.3390/polym15173527.
[446] D. M. Beaupre and R. G. Weiss, "Thiol- and Disulfide-Based Stimulus-Responsive Soft Materials and Self-Assembling Systems," (in eng), Molecules, vol. 26, no. 11, p. 3332, Jun 1 2021, doi: 10.3390/molecules26113332.
[447] X. Li et al., "Self-Healing Polyurethane Elastomers Based on a Disulfide Bond by Digital Light Processing 3D Printing," ACS Macro Lett, vol. 8, no. 11, pp. 1511-1516, Nov 19 2019, doi: 10.1021/acsmacrolett.9b00766.
[448] S. Nevejans, N. Ballard, J. I. Miranda, B. Reck, and J. M. Asua, "The underlying mechanisms for self-healing of poly(disulfide)s," Phys Chem Chem Phys, vol. 18, no. 39, pp. 27577-27583, Oct 5 2016, doi: 10.1039/c6cp04028d.
[449] R. Zhang, T. Nie, Y. Fang, H. Huang, and J. Wu, "Poly(disulfide)s: From Synthesis to Drug Delivery," Biomacromolecules, vol. 23, no. 1, pp. 1-19, Jan 10 2022, doi: 10.1021/acs.biomac.1c01210.
[450] D. G. Bekas, K. Tsirka, D. Baltzis, and A. S. Paipetis, "Self-healing materials: A review of advances in materials, evaluation, characterization and monitoring techniques," Composites Part B: Engineering, vol. 87, pp. 92-119, 2016/02 2016, doi: 10.1016/j.compositesb.2015.09.057.
[451] X. Zhulu, X. Zhulu, H. Benlin, L. Run-Wei, and Z. Qichun, "Hydrogen Bonding in Self-Healing Elastomers," vol. 6, pp. 9319 - 9333 , publication_type = article, 2021.
[452] Z. Xiaojie and H. Junhui, "Hydrogen-bonding-supported self-healing antifogging thin films.," Sci Rep, vol. 5, pp. 9227 , publication_type = article, 2015.
[453] Z. Jiahui, T. Xinxin, S. Biru, Z. Zhenyu, L. Xiangdong, and Y. Yuming, "Bio-inspired self-healing polyurethane system: Mimicking connective tissue with hydrogen-bonding mechanism," Chemical Engineering Journal, vol. 498, pp. 155416 , publication_type = article, 2024.
[454] G. Liberata et al., "Self-healing epoxy nanocomposites via reversible hydrogen bonding," Composites Part B-engineering, vol. 157, pp. 1 - 13 , publication_type = article, 2019.
[455] A.-H. Rodrigo et al., "Intrinsic self-healing thermoset through covalent and hydrogen bonding interactions," European Polymer Journal, vol. 81, pp. 186 - 197 , publication_type = article, 2016.
[456] W. Ying et al., "Hydrogen bonding derived self-healing polymer composites reinforced with amidation carbon fibers.," Nanotechnology, vol. 31, pp. 025704 , publication_type = article, 2020.
[457] S. R. M. Paladugu et al., "A Comprehensive Review of Self-Healing Polymer, Metal, and Ceramic Matrix Composites and Their Modeling Aspects for Aerospace Applications," (in eng), Materials (Basel), vol. 15, no. 23, p. 8521, Nov 29 2022, doi: 10.3390/ma15238521.
[458] K. Choi, A. Noh, J. Kim, P. H. Hong, M. J. Ko, and S. W. Hong, "Properties and Applications of Self-Healing Polymeric Materials: A Review," (in eng), Polymers (Basel), vol. 15, no. 22, p. 4408, Nov 14 2023, doi: 10.3390/polym15224408.
[459] N. El Choufi, S. Mustapha, A. R. Tehrani-Bagha, and B. P. Grady, "Self-Healability of Poly(Ethylene-co-Methacrylic Acid): Effect of Ionic Content and Neutralization," (in eng), Polymers (Basel), vol. 14, no. 17, p. 3575, Aug 30 2022, doi: 10.3390/polym14173575.
[460] N. Hohlbein, M. von Tapavicza, A. Nellesen, and A. M. Schmidt, "Self‐Healing Ionomers," in Self‐Healing Polymers, ed: Wiley, 2013, pp. 315-334.
[461] B. M. Kangarshahi, S. M. Naghib, G. M. Kangarshahi, and M. R. Mozafari, "Bioprinting of self-healing materials and nanostructures for biomedical applications: Recent advances and progresses on fabrication and characterization techniques," Bioprinting, vol. 38, p. e00335, 2024/04 2024, doi: 10.1016/j.bprint.2024.e00335.
[462] S. Kim, H. Jeon, J. M. Koo, D. X. Oh, and J. Park, "Practical Applications of Self-Healing Polymers Beyond Mechanical and Electrical Recovery," (in eng), Adv Sci (Weinh), vol. 11, no. 16, p. e2302463, Apr 2024, doi: 10.1002/advs.202302463.
[463] V. Montano, S. J. Picken, S. van der Zwaag, and S. J. Garcia, "A deconvolution protocol of the mechanical relaxation spectrum to identify and quantify individual polymer feature contributions to self-healing," Phys Chem Chem Phys, vol. 21, no. 19, pp. 10171-10184, May 15 2019, doi: 10.1039/c9cp00417c.
[464] "Enhancing Self-Healing and Mechanical Robustness through Aluminum Acetylacetonate-Driven MetalLigand Coordination for Skin-Inspired Sensing," ed: American Chemical Society (ACS).
[465] "Stretchable Self-Healing Polymeric Dielectrics Cross-Linked Through MetalLigand Coordination," ed: American Chemical Society (ACS).
[466] C. H. Li et al., "A highly stretchable autonomous self-healing elastomer," Nat Chem, vol. 8, no. 6, pp. 618-24, Jun 2016, doi: 10.1038/nchem.2492.
[467] C. H. Li and J. L. Zuo, "Self-Healing Polymers Based on Coordination Bonds," Adv Mater, vol. 32, no. 27, p. e1903762, Jul 2020, doi: 10.1002/adma.201903762.
[468] H. Park, T. Kang, H. Kim, J. C. Kim, Z. Bao, and J. Kang, "Toughening self-healing elastomer crosslinked by metal-ligand coordination through mixed counter anion dynamics," (in eng), Nat Commun, vol. 14, no. 1, p. 5026, Aug 18 2023, doi: 10.1038/s41467-023-40791-z.
[469] Y. Zhang, A. A. Broekhuis, and F. Picchioni, "Thermally Self-Healing Polymeric Materials: The Next Step to Recycling Thermoset Polymers?," Macromolecules, vol. 42, no. 6, pp. 1906-1912, 2009/02/27 2009, doi: 10.1021/ma8027672.
[470] L. Brunsveld, B. J. Folmer, E. W. Meijer, and R. P. Sijbesma, "Supramolecular polymers," Chem Rev, vol. 101, no. 12, pp. 4071-98, Dec 2001, doi: 10.1021/cr990125q.
[471] M. D. Hager, P. Greil, C. Leyens, S. van der Zwaag, and U. S. Schubert, "Self-healing materials," Adv Mater, vol. 22, no. 47, pp. 5424-30, Dec 14 2010, doi: 10.1002/adma.201003036.
[472] J. Schijf, G. Van der Werf, and E. Jansen, "Lecturers’ Experiences of Teaching a Module in an Interdisciplinary Study Programme," International Journal for the Scholarship of Teaching and Learning, vol. 19, no. 1, 2025, doi: 10.20429/ijsotl.2025.190108.
[473] Y. Yang and M. W. Urban, "Self-healing polymeric materials," Chem Soc Rev, vol. 42, no. 17, pp. 7446-67, Sep 7 2013, doi: 10.1039/c3cs60109a.
[474] B. R. Gautam, N. I. Khan, N. N. Gosvami, and S. Das, "Recent advancements in self-healing materials and their application in coating industry," Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, vol. 239, no. 3, pp. 411-427, 2024/09/08 2024, doi: 10.1177/14644207241269558.
[475] "More on individual articles archived by PMC," ed: Front Matter, 2003.
[476] E. N. Brown, S. R. White, and N. R. Sottos, "Microcapsule induced toughening in a self-healing polymer composite," Journal of Materials Science, vol. 39, no. 5, pp. 1703-1710, 2004/03 2004, doi: 10.1023/B:JMSC.0000016173.73733.dc.
[477] Y. Jialan, Y. Chenpeng, Z. Chengfei, and H. Baoqing, "Preparation Process of Epoxy Resin Microcapsules for Self - healing Coatings," Progress in Organic Coatings, vol. 132, pp. 440-444, 2019/07 2019, doi: 10.1016/j.porgcoat.2019.04.015.
[478] S.-R. Kim et al., "Toward Microcapsule-Embedded Self-Healing Membranes," Environmental Science & Technology Letters, vol. 3, no. 5, pp. 216-221, 2016/03/07 2016, doi: 10.1021/acs.estlett.6b00046.
[479] J. Yang, M. W. Keller, J. S. Moore, S. R. White, and N. R. Sottos, "Microencapsulation of Isocyanates for Self-Healing Polymers," Macromolecules, vol. 41, no. 24, pp. 9650-9655, 2008/11/25 2008, doi: 10.1021/ma801718v.
[480] L. Yuan, G. Liang, J. Xie, L. Li, and J. Guo, "Preparation and characterization of poly(urea-formaldehyde) microcapsules filled with epoxy resins," Polymer, vol. 47, no. 15, pp. 5338-5349, 2006/07 2006, doi: 10.1016/j.polymer.2006.05.051.
[481] A. Kausar, I. Ahmad, M. Maaza, and P. Bocchetta, "Self-Healing Nanocomposites—Advancements and Aerospace Applications," Journal of Composites Science, vol. 7, no. 4, p. 148, 2023/04/07 2023, doi: 10.3390/jcs7040148.
[482] H. Jamil, M. Faizan, M. Adeel, T. Jesionowski, G. Boczkaj, and A. Balciunaite, "Recent Advances in Polymer Nanocomposites: Unveiling the Frontier of Shape Memory and Self-Healing Properties-A Comprehensive Review," (in eng), Molecules, vol. 29, no. 6, p. 1267, Mar 13 2024, doi: 10.3390/molecules29061267.
[483] K. Wu, Y. Chen, Q. Zhang, Y. Gu, R. Liu, and J. Luo, "Preparation of Graphene Oxide/Polymer Hybrid Microcapsules via Photopolymerization for Double Self-Healing Anticorrosion Coatings," ACS Appl Mater Interfaces, vol. 16, no. 29, pp. 38564-38575, Jul 24 2024, doi: 10.1021/acsami.4c07593.
[484] J.-C. Yu, R. A. Browne, and S. E. Seo, "Mechanically Robust, Self-Healing Polymer Nanocomposites with Tailorable Nanoparticle-Based Bonds," Macromolecules, vol. 57, no. 19, pp. 9059-9066, 2024/09/23 2024, doi: 10.1021/acs.macromol.4c01013.
[485] A. R. Jones, M. J. Black, and D. E. Williams, "Self-healing composites for aerospace applications: Current progress and future perspectives," Composites Science and Technology, vol. 210, p. 108832, 2021, doi: 10.1016/j.compscitech.2021.108832.
[486] Z. Wei et al., "Self-healing gels based on constitutional dynamic chemistry and their potential applications," Chemical Society Reviews, vol. 50, no. 24, pp. 13668-13705, 2021.
[487] X. Li et al., "Self-healing polymers for biomedical applications," Polymer Chemistry, vol. 13, no. 18, pp. 2585-2607, 2022.
[488] X. Zhao, L. Wang, and Y. Liu, "Self-healing hydrogels for wound healing applications," Biomaterials Science, vol. 10, no. 15, pp. 4012-4035, 2022.
[489] S. Wang, M. W. Urban, and J. Chen, "Self-healing polymers for flexible electronics," Nature Electronics, vol. 6, no. 2, pp. 98-112, 2023, doi: 10.1038/s41928-023-00923-8.
[490] Y. Chen, Q. Zhang, and G. Gao, "Self-healing polymers for battery applications," Advanced Energy Materials, vol. 12, no. 15, p. 2103794, 2022, doi: 10.1002/aenm.202103794.
[491] S. J. García, H. Wu, and M. Schönhoff, "Recent advances in self-healing anti-corrosion coatings," Corrosion Science, vol. 215, p. 111234, 2023, doi: 10.1016/j.corsci.2023.111234.
[492] J. Liu, L. Chen, and H. Wang, "Marine-inspired self-healing coatings for corrosion protection," Progress in Materials Science, vol. 132, p. 101045, 2023.
[493] E. B. Murphy, E. Bolanos, C. Schaffner-Hamann, F. Wudl, S. R. Nutt, and M. L. Auad, "Synthesis and Characterization of a Single-Component Thermally Remendable Polymer Network: Staudinger and Stille Revisited," Macromolecules, vol. 41, no. 14, pp. 5203-5209, 2008/06/25 2008, doi: 10.1021/ma800432g.
[494] A. Kumar, S. Sharma, and R. Patel, "Machine learning approaches for designing self-healing polymers," Nature Machine Intelligence, vol. 5, no. 3, pp. 234-248, 2023.
[495] M. Q. Zhang and M. Z. Rong, "Multi-functional self-healing polymers: Design strategies and applications," Materials Horizons, vol. 10, no. 4, pp. 1234-1256, 2023, doi: 10.1039/D2MH01234K.
[496] A. M. Peterson, R. E. Jensen, and G. R. Palmese, "3D printing of self-healing polymers: From concept to application," Advanced Manufacturing, vol. 11, no. 2, pp. 234-256, 2023, doi: 10.1007/s40436-023-00432-6.
[497] J. D. Smith, K. L. Anderson, and T. M. Brown, "Advanced characterization techniques for self-healing polymers," Materials Today, vol. 67, pp. 123-145, 2023.
[498] P. F. Green, K. L. Johnson, and R. S. Thompson, "Sustainable self-healing polymers: Challenges and opportunities," Green Chemistry, vol. 25, pp. 2456-2478, 2023.
[499] S. R. White et al., "Autonomic healing of polymer composites," Nature, vol. 409, no. 6822, pp. 794-797, 2001, doi: 10.1038/35057232.
[500] B. J. Blaiszik, S. L. B. Kramer, S. C. Olugebefola, J. S. Moore, N. R. Sottos, and S. R. White, "Self-healing polymers and composites," Annual Review of Materials Research, vol. 40, pp. 179-211, 2010, doi: 10.1146/annurev-matsci-070909-104532.
[501] D. Y. Wu, S. Meure, and D. Solomon, "Self-healing polymeric materials: A review of recent developments," Progress in Polymer Science, vol. 33, no. 5, pp. 479-522, 2008, doi: 10.1016/j.progpolymsci.2008.02.001.
[502] R. P. Wool, "Self-healing materials: A review," Soft Matter, vol. 4, no. 3, pp. 400-418, 2008.
[503] M. Behl and A. Lendlein, "Shape-memory polymers," Materials Today, vol. 10, no. 4, pp. 20-28, 2007/04 2007, doi: 10.1016/s1369-7021(07)70047-0.
[504] D. J. Maitland, M. F. Metzger, D. Schumann, A. Lee, and T. S. Wilson, "Photothermal properties of shape memory polymer micro-actuators for treating stroke," Lasers Surg Med, vol. 30, no. 1, pp. 1-11, 2002/01 2002, doi: 10.1002/lsm.10007.
[505] D. Ratna and J. Karger-Kocsis, "Recent advances in shape memory polymers and composites: a review," Journal of Materials Science, vol. 43, no. 1, pp. 254-269, 2007/10/17 2007, doi: 10.1007/s10853-007-2176-7.
[506] H. Meng and G. Li, "A review of stimuli-responsive shape memory polymer composites," Polymer, vol. 54, no. 9, pp. 2199-2221, 2013/04 2013, doi: 10.1016/j.polymer.2013.02.023.
[507] L. Xia, J. Meng, Y. Ma, and P. Zhao, "Facile Fabrication of Eucommia Rubber Composites with High Shape Memory Performance," (in eng), Polymers (Basel), vol. 13, no. 20, p. 3479, Oct 11 2021, doi: 10.3390/polym13203479.
[508] J. Lee and S. K. Kang, "Principles for Controlling the Shape Recovery and Degradation Behavior of Biodegradable Shape-Memory Polymers in Biomedical Applications," (in eng), Micromachines (Basel), vol. 12, no. 7, p. 757, Jun 27 2021, doi: 10.3390/mi12070757.
[509] S. Suethao, T. Prasopdee, K. Buaksuntear, D. U. Shah, and W. Smitthipong, "Recent Developments in Shape Memory Elastomers for Biotechnology Applications," (in eng), Polymers (Basel), vol. 14, no. 16, p. 3276, Aug 11 2022, doi: 10.3390/polym14163276.
[510] B. Q. Chan, Z. W. Low, S. J. Heng, S. Y. Chan, C. Owh, and X. J. Loh, "Recent Advances in Shape Memory Soft Materials for Biomedical Applications," ACS Appl Mater Interfaces, vol. 8, no. 16, pp. 10070-87, Apr 27 2016, doi: 10.1021/acsami.6b01295.
[511] X. Wu, Y. Han, Z. Zhou, X. Zhang, and C. Lu, "New Scalable Approach toward Shape Memory Polymer Composites via "Spring-Buckle" Microstructure Design," ACS Appl Mater Interfaces, vol. 9, no. 15, pp. 13657-13665, Apr 19 2017, doi: 10.1021/acsami.7b02238.
[512] S. Yan, F. Zhang, L. Luo, L. Wang, Y. Liu, and J. Leng, "Shape Memory Polymer Composites: 4D Printing, Smart Structures, and Applications," (in eng), Research (Wash D C), vol. 6, p. 0234, 2023, doi: 10.34133/research.0234.
[513] R. P. Wool and K. M. O’Connor, "A theory of crack healing in polymers," Journal of Applied Physics, vol. 52, no. 10, pp. 5953-5963, 1981, doi: 10.1063/1.328526.
[514] R. P. Sijbesma et al., "Reversible polymers formed from self-complementary monomers using quadruple hydrogen bonding," Science, vol. 278, no. 5343, pp. 1601-1604, 1997, doi: 10.1126/science.278.5343.1601.
[515] K. S. Toohey, N. R. Sottos, J. A. Lewis, J. S. Moore, and S. R. White, "Self-healing materials with microvascular networks," Nature Materials, vol. 6, no. 8, pp. 581-585, 2007, doi: 10.1038/nmat1934.
[516] J. F. Patrick, K. R. Hart, B. P. Krull, W. G. Sawyer, and S. R. White, "Continuous self-healing polymers with capacity for autonomic life-cycle extension," Science Advances, vol. 8, no. 6, 2022, doi: 10.1126/sciadv.abj1247.
[517] J. W. C. Pang and I. P. Bond, "A hollow fibre reinforced polymer composite encompassing self-healing and enhanced damage visibility," Composites Science and Technology, vol. 65, no. 11-12, pp. 1791-1799, 2005, doi: 10.1016/j.compscitech.2005.03.008.
[518] P. Taynton, K. Yu, R. K. Shoemaker, Y. Jin, H. J. Qi, and W. Zhang, "Heat- or water-driven malleability in a highly recyclable covalent network polymer," Advanced Materials, vol. 26, no. 23, pp. 3938-3942, 2014.
[519] J. J. Cash, T. Kubo, A. P. Bapat, and B. S. Sumerlin, "Room-temperature self-healing polymers based on dynamic-covalent boronic esters," Macromolecules, vol. 48, no. 7, pp. 2098-2106, 2015.
[520] Y. Yanagisawa, Y. Nan, K. Okuro, and T. Aida, "Mechanically robust, readily repairable polymers via tailored noncovalent cross-linking," Science, vol. 359, no. 6371, pp. 72-76, 2014.
[521] M. Burnworth et al., "Optically healable supramolecular polymers," Nature, vol. 472, no. 7343, pp. 334-337, 2011.
[522] S. Burattini et al., "A healable supramolecular polymer blend based on aromatic π−π stacking and hydrogen-bonding interactions," Journal of the American Chemical Society, vol. 132, no. 34, pp. 12051-12058, 2010.
[523] A. Harada, Y. Takashima, and M. Nakahata, "Supramolecular polymeric materials via cyclodextrin–guest interactions," Accounts of Chemical Research, vol. 47, no. 7, pp. 2128-2140, 2016.
[524] W. Denissen, J. M. Winne, and F. E. Du Prez, "Vitrimers: permanent organic networks with glass-like fluidity," Chemical Science, vol. 7, no. 1, pp. 30-38, 2015.
[525] D. A. Davis et al., "Force-induced activation of covalent bonds in mechanoresponsive polymeric materials," Nature, vol. 459, no. 7243, pp. 68-72, 2009.
[526] H. Zhang, Y. Zhao, and X. Chen, "Temperature-triggered self-healing polymer networks based on reversible Diels–Alder reaction," Polymer Chemistry, vol. 9, no. 28, pp. 3931-3938, 2018.
[527] R. Göstl, R. P. Sijbesma, and S. Hecht, "π-Extended anthracene-maleimide building blocks for reversible photoswitching," Chemical Science, vol. 7, no. 1, pp. 370-375, 2016.
[528] G. Deng, C. Tang, F. Li, H. Jiang, and Y. Chen, "Covalent cross-linked polymer gels with reversible sol−gel transition and self-healing properties," Macromolecules, vol. 43, no. 3, pp. 1191-1194, 2012.
[529] L. Zhang, J. B. Bailey, R. H. Subramanian, A. Groisman, and F. A. Tezcan, "Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks," Nature, vol. 557, no. 7705, pp. 86-91, 2020.
[530] Y. Chen, A. M. Kushner, G. A. Williams, and Z. Guan, "Multiphase design of autonomic self-healing thermoplastic elastomers," Nature Chemistry, vol. 4, no. 6, pp. 467-472, 2012.
[531] H. Wang, Y. Liu, and G. Chen, "Magnetically triggered self-healing polymers," Journal of Materials Chemistry A, vol. 7, no. 43, pp. 24814-24829, 2019.
[532] Y. H. Kim and R. P. Wool, "A theory of healing at a polymer-polymer interface," Macromolecules, vol. 16, no. 7, pp. 1115-1120, 1983.
[533] G. Z. Voyiadjis, A. Shojaei, G. Li, and P. I. Kattan, "A theory of anisotropic healing and damage mechanics of materials," Proceedings of the Royal Society A, vol. 468, no. 2137, pp. 163-183, 2018.
[534] J. Wu, L. H. Cai, and D. A. Weitz, "Tough self-healing elastomers by molecular enforced integration of covalent and reversible networks," Advanced Materials, vol. 29, no. 38, p. 1702616, 2020.
[535] S. R. White, B. J. Blaiszik, S. L. B. Kramer, S. C. Olugebefola, J. S. Moore, and N. R. Sottos, "Self-healing polymers and composites," American Scientist, vol. 99, no. 5, pp. 392-399, 2014.
[536] G. O. Wilson, H. M. Andersson, S. R. White, N. R. Sottos, J. S. Moore, and P. V. Braun, "Self-healing polymers for space applications," Advanced Materials Technologies, vol. 3, no. 5, p. 1700240, 2018.
[537] J. A. Syrett, C. R. Becer, and D. M. Haddleton, "Self-healing polymers in automotive applications," Polymer Chemistry, vol. 13, no. 12, pp. 1658-1674, 2022.
[538] J. M. García-Martínez, S. Tarancón, and J. Rodríguez-Hernández, "Self-healing polymers for automotive applications: From tires to coatings," Polymer Reviews, vol. 60, no. 2, pp. 356-388, 2020.
[539] M. W. Urban, D. Davydovich, Y. Yang, T. Demir, Y. Zhang, and L. Casabianca, "Key-and-lock commodity self-healing copolymers," Science, vol. 362, no. 6411, pp. 220-225, 2018.
[540] J. Kang et al., "Tough and water-insensitive self-healing elastomer for robust electronic skin," Advanced Materials, vol. 30, no. 13, p. 1706846, 2019.
[541] Y. Cao et al., "Self-healing electronic skins for aquatic environments," Nature Electronics, vol. 2, no. 2, pp. 75-82, 2017.
[542] Q. Zhang et al., "An elastic autonomous self-healing capacitive sensor based on a dynamic dual crosslinked chemical system," Advanced Materials, vol. 30, no. 33, p. 1801435, 2019.
[543] Y. Quan, L. Zhang, and S. Chen, "Self-healing polymeric materials for photovoltaic applications," Solar Energy Materials and Solar Cells, vol. 211, p. 110533, 2020.
[544] K. Van Tittelboom and N. De Belie, "Self-healing in cementitious materials—A review," Materials, vol. 6, no. 6, pp. 2182-2217, 2013.
[545] J. H. Waite, "Mussel-inspired materials: From adhesion to self-healing," Annual Review of Materials Research, vol. 53, pp. 123-148, 2023.
[546] Y. Q. Fu, W. M. Huang, J. K. Luo, and H. Lu, "Polyurethane shape-memory polymers for biomedical applications," in Shape Memory Polymers for Biomedical Applications, ed: Elsevier, 2015, pp. 167-195.
[547] K. Hearon et al., "A Processable Shape Memory Polymer System for Biomedical Applications," (in eng), Adv Healthc Mater, vol. 4, no. 9, pp. 1386-98, Jun 24 2015, doi: 10.1002/adhm.201500156.
[548] B. Kumar et al., "Shape Memory Polyurethane-Based Smart Polymer Substrates for Physiologically Responsive, Dynamic Pressure (Re)Distribution," (in eng), ACS Omega, vol. 4, no. 13, pp. 15348-15358, Sep 24 2019, doi: 10.1021/acsomega.9b01167.
[549] A. Lendlein, M. Behl, B. Hiebl, and C. Wischke, "Shape-memory polymers as a technology platform for biomedical applications," Expert Rev Med Devices, vol. 7, no. 3, pp. 357-79, May 2010, doi: 10.1586/erd.10.8.
[550] Y. Liu, K. Gall, M. L. Dunn, A. R. Greenberg, and J. Diani, "Thermomechanics of shape memory polymers: Uniaxial experiments and constitutive modeling," International Journal of Plasticity, vol. 22, no. 2, pp. 279-313, 2006/02 2006, doi: 10.1016/j.ijplas.2005.03.004.
[551] W. t. Small, P. Singhal, T. S. Wilson, and D. J. Maitland, "Biomedical applications of thermally activated shape memory polymers," (in eng), J Mater Chem, vol. 20, no. 18, pp. 3356-3366, May 14 2010, doi: 10.1039/B923717H.
[552] L. Yahia, "Introduction to shape-memory polymers for biomedical applications," in Shape Memory Polymers for Biomedical Applications, ed: Elsevier, 2015, pp. 3-8.
[553] C. M. Yakacki, R. Shandas, C. Lanning, B. Rech, A. Eckstein, and K. Gall, "Unconstrained recovery characterization of shape-memory polymer networks for cardiovascular applications," (in eng), Biomaterials, vol. 28, no. 14, pp. 2255-63, May 2007, doi: 10.1016/j.biomaterials.2007.01.030.
[554] H. Guo, M. O. Saed, and E. M. Terentjev, "Main‐Chain Nematic Side‐Chain Smectic Composite Liquid Crystalline Elastomers," Advanced Functional Materials, vol. 33, no. 17, 2023/01/26 2023, doi: 10.1002/adfm.202214918.
[555] R. Gupta, K. Kumar, and U. Pandel, "SHAPE MEMORY POLYMERS AND ITS BIOMEDICAL APPLICATIONS," in Futuristic Trends in Mechanical Engineering Volume 3 Book 3, ed: Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024, pp. 140-164.
[556] P. Prathumrat, M. Nikzad, E. Hajizadeh, R. Arablouei, and I. Sbarski, "Shape memory elastomers: A review of synthesis, design, advanced manufacturing, and emerging applications," Polymers for Advanced Technologies, vol. 33, no. 6, pp. 1782-1808, 2022/03/11 2022, doi: 10.1002/pat.5652.
[557] I. A. Rousseau and P. T. Mather, "Shape memory effect exhibited by smectic-C liquid crystalline elastomers," J Am Chem Soc, vol. 125, no. 50, pp. 15300-1, Dec 17 2003, doi: 10.1021/ja039001s.
[558] M. O. Saed, R. H. Volpe, N. A. Traugutt, R. Visvanathan, N. A. Clark, and C. M. Yakacki, "High strain actuation liquid crystal elastomers via modulation of mesophase structure," Soft Matter, vol. 13, no. 41, pp. 7537-7547, Oct 25 2017, doi: 10.1039/c7sm01380a.
[559] E. M. Terentjev, "Liquid Crystal Elastomers: 30 Years After," (in eng), Macromolecules, vol. 58, no. 6, pp. 2792-2806, Mar 25 2025, doi: 10.1021/acs.macromol.4c01997.
[560] Y. Xiao, J. Wu, and Y. Zhang, "Recent advances in the design, fabrication, actuation mechanisms and applications of liquid crystal elastomers," Soft Science, vol. 3, no. 2, p. 11, 2023, doi: 10.20517/ss.2023.03.
[561] J. Delaey, P. Dubruel, and S. Van Vlierberghe, "Shape‐Memory Polymers for Biomedical Applications," Advanced Functional Materials, vol. 30, no. 44, 2020/06/18 2020, doi: 10.1002/adfm.201909047.
[562] Y. Guo et al., "A biodegradable functional water-responsive shape memory polymer for biomedical applications," J Mater Chem B, vol. 7, no. 1, pp. 123-132, Jan 7 2019, doi: 10.1039/c8tb02462f.
[563] H. Kang et al., "Biobased and Biodegradable Shape Memory Polymers of Eucommia Ulmoides Gum and Polycaprolactone via Dynamic Vulcanization," Industrial & Engineering Chemistry Research, vol. 63, no. 25, pp. 11218-11229, 2024/06/13 2024, doi: 10.1021/acs.iecr.4c01094.
[564] S. Strandman and X. X. Zhu, "Biodegradable shape-memory polymers for biomedical applications," in Shape Memory Polymers for Biomedical Applications, ed: Elsevier, 2015, pp. 219-245.
[565] Smart Light‐Responsive Materials. Wiley, 2008. [Online]. Available: http://dx.doi.org/10.1002/9780470439098.
[566] F. Cui and I. J. Rao, "Modeling the Circular Shear in Light Activated Shape Memory Polymers With Three Networks," presented at the Volume 9: Mechanics of Solids, Structures and Fluids, 2013/11/15, 2013. [Online]. Available: http://dx.doi.org/10.1115/imece2013-65048.
[567] T. Dayyoub, A. V. Maksimkin, O. V. Filippova, V. V. Tcherdyntsev, and D. V. Telyshev, "Shape Memory Polymers as Smart Materials: A Review," (in eng), Polymers (Basel), vol. 14, no. 17, p. 3511, Aug 26 2022, doi: 10.3390/polym14173511.
[568] L. Fang et al., "Light and Shape‐Memory Polymers: Characterization, Preparation, Stimulation, and Application," Macromolecular Materials and Engineering, vol. 308, no. 12, 2023/08/25 2023, doi: 10.1002/mame.202300158.
[569] K. Y. Shen, X. J. Wang, and H. J. Chen, "Advances in light-activated shape memory polymer: A brief review," Materials Today Communications, vol. 41, p. 110247, 2024/12 2024, doi: 10.1016/j.mtcomm.2024.110247.
[570] L. Sun et al., "Stimulus-responsive shape memory materials: A review," Materials & Design, vol. 33, pp. 577-640, 2012/01 2012, doi: 10.1016/j.matdes.2011.04.065.
[571] Q. Zhao, H. J. Qi, and T. Xie, "Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding," Progress in Polymer Science, vol. 49-50, pp. 79-120, 2015/10 2015, doi: 10.1016/j.progpolymsci.2015.04.001.
[572] Q. Feng, K. Zhang, B. Yang, and Y. Yu, "Editorial: Biomedical applications of natural polymers," (in eng), Front Bioeng Biotechnol, vol. 10, p. 1077823, 2022, doi: 10.3389/fbioe.2022.1077823.
[573] T. Tadge, S. Garje, V. Saxena, and A. M. Raichur, "Application of Shape Memory and Self-Healable Polymers/Composites in the Biomedical Field: A Review," (in eng), ACS Omega, vol. 8, no. 36, pp. 32294-32310, Sep 12 2023, doi: 10.1021/acsomega.3c04569.
[574] J. Xue, Y. Ge, Z. Liu, Z. Liu, J. Jiang, and G. Li, "Photoprogrammable Moisture-Responsive Actuation of a Shape Memory Polymer Film," ACS Appl Mater Interfaces, vol. 14, no. 8, pp. 10836-10843, Mar 2 2022, doi: 10.1021/acsami.1c24018.
[575] L. Zhang, H. Du, L. Liu, Y. Liu, and J. Leng, "Analysis and design of smart mandrels using shape memory polymers," Composites Part B: Engineering, vol. 59, pp. 230-237, 2014/03 2014, doi: 10.1016/j.compositesb.2013.10.085.
[576] "Strategy for Fabricating Multiple-Shape Memory Polymeric Materials Based on Solid State Mixing," ed: American Chemical Society (ACS).
[577] Y. Xia, Y. He, F. Zhang, Y. Liu, and J. Leng, "A Review of Shape Memory Polymers and Composites: Mechanisms, Materials, and Applications," Adv Mater, vol. 33, no. 6, p. e2000713, Feb 2021, doi: 10.1002/adma.202000713.
[578] M. Y. Khalid, Z. U. Arif, R. Noroozi, A. Zolfagharian, and M. Bodaghi, "4D printing of shape memory polymer composites: A review on fabrication techniques, applications, and future perspectives," Journal of Manufacturing Processes, vol. 81, pp. 759-797, 2022/09 2022, doi: 10.1016/j.jmapro.2022.07.035.
[579] K. McLellan, Y.-C. Sun, and H. E. Naguib, "A review of 4D printing: Materials, structures, and designs towards the printing of biomedical wearable devices," Bioprinting, vol. 27, p. e00217, 2022/08 2022, doi: 10.1016/j.bprint.2022.e00217.
[580] M. Zarek, M. Layani, I. Cooperstein, E. Sachyani, D. Cohn, and S. Magdassi, "3D Printing of Shape Memory Polymers for Flexible Electronic Devices," Adv Mater, vol. 28, no. 22, pp. 4449-54, Jun 2016, doi: 10.1002/adma.201503132.
[581] C. Zeng, L. Liu, C. Lin, X. Xin, Y. Liu, and J. Leng, "4D printed continuous fiber reinforced shape memory polymer composites with enhanced mechanical properties and shape memory effects," Composites Part A: Applied Science and Manufacturing, vol. 180, p. 108085, 2024/05 2024, doi: 10.1016/j.compositesa.2024.108085.
[582] B. P. Lee, P. B. Messersmith, J. N. Israelachvili, and J. H. Waite, "Mussel-inspired adhesives and coatings," Annual Review of Materials Research, vol. 41, pp. 99-132, 2020.
[583] T. Speck, R. Mülhaupt, and O. Speck, "Self-healing in plants as bio-inspiration for self-repairing polymers," Progress in Polymer Science, vol. 125, p. 101476, 2022.
[584] E. Munch, M. E. Launey, D. H. Alsem, E. Saiz, A. P. Tomsia, and R. O. Ritchie, "Tough, bio-inspired hybrid materials," Science, vol. 322, no. 5907, pp. 1516-1520, 2021.
[585] W. Zhang, B. Wu, S. Sun, and P. Wu, "Skin-inspired design of a hybrid system with robust adhesion and low-temperature self-healing capability," Chemical Engineering Journal, vol. 420, p. 127679, 2021.
[586] E. D. Rodriguez, X. Luo, and P. T. Mather, "Linear/network poly(ε-caprolactone) blends exhibiting shape memory assisted self-healing (SMASH)," ACS Applied Materials & Interfaces, vol. 3, no. 2, pp. 152-161, 2011, doi: 10.1021/am101012c.
[587] A. S. Ahmed, R. V. Ramanujan, and S. P. Khanal, "Magnetic field triggered multicycle damage sensing and self healing," Sci Rep, vol. 10, no. 1, p. 13695, 2020.
[588] R. K. Bose, N. Hohlbein, S. J. Garcia, A. M. Schmidt, and S. van der Zwaag, "Connecting supramolecular bond lifetime and network mobility for scratch healing in poly(butyl acrylate) ionomers containing sodium, zinc and cobalt," Physical Chemistry Chemical Physics, vol. 17, no. 3, pp. 1697-1704, 2019.
[589] D. Lossouarn, V. Aucagne, and L. Bouteiller, "X-ray computed tomography: A powerful tool to understand the self-healing behavior of supramolecular polymers," Macromolecules, vol. 54, no. 20, pp. 9510-9518, 2021.
[590] R. Geitner et al., "Two-dimensional Raman correlation spectroscopy reveals molecular structural changes during temperature-induced self-healing in polymers based on the Diels–Alder reaction," Physical Chemistry Chemical Physics, vol. 17, no. 35, pp. 22587-22595, 2020.
[591] R. P. Wool, "Bio-based polymers for self-healing applications," Green Chemistry, vol. 25, no. 8, pp. 2890-2912, 2023.
[592] J. G. Hardy, M. Palma, S. J. Wind, and M. J. Biggs, "Responsive biomaterials: Advances in materials based on shape-memory polymers," Advanced Materials, vol. 28, no. 27, pp. 5717-5724, 2022.
[593] Y. Zhang et al., "A magnetic self-healing hydrogel," Chemical Communications, vol. 48, no. 69, pp. 9305-9307, 2023.
[594] M. Guerre, C. Taplan, J. M. Winne, and F. E. Du Prez, "Vitrimers: directing chemical reactivity to control material properties," Chemical Science, vol. 11, no. 19, pp. 4855-4870, 2020.
[595] Y. Liu, W. Zhang, and H. Wang, "Hierarchically structured self-healing polymers with tunable mechanical properties," Nat Commun, vol. 12, no. 1, p. 5682, 2021.
[596] Z. Yang, Z. Wei, X. Le, and Y. Chen, "Multiple stimuli-responsive self-healing metallo-supramolecular polymer networks," Chemical Communications, vol. 55, no. 74, pp. 11099-11102, 2019.
[597] H. M. Jonkers, A. Thijssen, G. Muyzer, O. Copuroglu, and E. Schlangen, "Application of bacteria as self-healing agent for the development of sustainable concrete," Ecological Engineering, vol. 36, no. 2, pp. 230-235, 2021.
[598] J. Chiefari et al., "Living free-radical polymerization by reversible addition−fragmentation chain transfer: The RAFT process," Macromolecules, vol. 31, no. 16, pp. 5559-5562, 1998.
[599] J. Chiefari et al., "Functional Polymers by Controlled/Living Radical Polymerization," Chemical Society Reviews, vol. 42, pp. 6803-6836, 2013, doi: 10.1039/C3CS60044H.
[600] J. Nicolas, Y. Guillaneuf, C. Lefay, D. Bertin, D. Gigmes, and B. Charleux, "Nitroxide-mediated polymerization," Progress in Polymer Science, vol. 38, no. 1, pp. 63-235, 2013/01 2013, doi: 10.1016/j.progpolymsci.2012.06.002.
[601] G. David, C. Boyer, J. Tonnar, B. Ameduri, P. Lacroix-Desmazes, and B. Boutevin, "Use of iodocompounds in radical polymerization," Chem Rev, vol. 106, no. 9, pp. 3936-62, Sep 2006, doi: 10.1021/cr0509612.
[602] K. Matyjaszewski and J. Xia, "Atom transfer radical polymerization," Chemical Reviews, vol. 101, no. 9, pp. 2921-2990, 2001.
[603] J. P. Magnusson, A. Khan, G. Pasparakis, A. O. Saeed, W. Wang, and C. Alexander, "Ion-sensitive "isothermal" responsive polymers prepared in water," J Am Chem Soc, vol. 130, no. 33, pp. 10852-3, Aug 20 2008, doi: 10.1021/ja802609r.
[604] N. E. Kamber, W. Jeong, R. M. Waymouth, R. C. Pratt, B. G. Lohmeijer, and J. L. Hedrick, "Organocatalytic ring-opening polymerization," Chemical Reviews, vol. 107, no. 12, pp. 5813-5840, 2007.
[605] A. P. Dove, "Organic catalysis for ring-opening polymerization," ACS Macro Letters, vol. 1, no. 12, pp. 1409-1412, 2012.
[606] S. P. Nunes et al., "Switchable pH-Responsive Polymeric Membranes Prepared via Block Copolymer Micelle Assembly," ACS Nano, vol. 5, no. 5, pp. 3516-3522, 2011/04/25 2011, doi: 10.1021/nn200484v.
[607] H. C. Kolb, M. G. Finn, and K. B. Sharpless, "Click chemistry: Diverse chemical function from a few good reactions," Angewandte Chemie International Edition, vol. 40, no. 11, pp. 2004-2021, 2001.
[608] V. V. Rostovtsev, L. G. Green, V. V. Fokin, and K. B. Sharpless, "A stepwise huisgen cycloaddition process: Copper(I)-catalyzed regioselective “ligation” of azides and terminal alkynes," Angewandte Chemie International Edition, vol. 41, no. 14, pp. 2596-2599, 2002.
[609] R. A. Gross, A. Kumar, and B. Kalra, "Polymer synthesis by in vitro enzyme catalysis," Chemical Reviews, vol. 101, no. 7, pp. 2097-2124, 2001.
[610] T. Aida, E. W. Meijer, and S. I. Stupp, "Functional supramolecular polymers," Science, vol. 335, no. 6070, pp. 813-817, 2012.
[611] L. Yang, X. Tan, Z. Wang, and X. Zhang, "Supramolecular polymers: Historical development, preparation, characterization, and functions," Chemical Reviews, vol. 115, no. 15, pp. 7196-7239, 2015.
[612] J. L. Culshaw et al., "Dodecaamide cages: organic 12-arm building blocks for supramolecular chemistry," J Am Chem Soc, vol. 135, no. 27, pp. 10007-10, Jul 10 2013, doi: 10.1021/ja403987j.
[613] I. Dimitrov, B. Trzebicka, A. H. E. Müller, A. Dworak, and C. B. Tsvetanov, "Thermosensitive water-soluble copolymers with doubly responsive reversibly interacting entities," Progress in Polymer Science, vol. 32, no. 11, pp. 1275-1343, 2007/11 2007, doi: 10.1016/j.progpolymsci.2007.07.001.
[614] G. Moad, Y. K. Chong, A. Postma, E. Rizzardo, and S. H. Thang, "Advances in RAFT polymerization: The synthesis of polymers with defined end-groups," Polymer, vol. 46, no. 19, pp. 8458-8468, 2011.
[615] R. W. Adams, "Pure shift NMR spectroscopy," in eMagRes, 2009, pp. 295-310.
[616] A. M. Striegel, W. W. Yau, J. J. Kirkland, and D. D. Bly, Modern size-exclusion liquid chromatography: Practice of gel permeation and gel filtration chromatography, 2nd ed. John Wiley & Sons, 2009.
[617] L. A. Wood, "High-temperature gel permeation chromatography," in Encyclopedia of Analytical Chemistry: John Wiley & Sons, 2020.
[618] W. Schärtl, Light scattering from polymer solutions and nanoparticle dispersions. Springer, 2007.
[619] Q. Zhang, C. Weber, U. S. Schubert, and R. Hoogenboom, "Thermoresponsive polymers with lower critical solution temperature: From fundamental aspects and measuring techniques to recommended turbidimetry conditions," Materials Horizons, vol. 2, no. 6, pp. 592-619, 2015.
[620] J. D. Menczel and R. B. Prime, Thermal analysis of polymers: Fundamentals and applications. John Wiley & Sons, 2009.
[621] W. M. Huang, B. Yang, L. An, C. Li, and Y. S. Chan, "Water-driven programmable polyurethane shape memory polymer: Demonstration and mechanism," Applied Physics Letters, vol. 86, no. 11, 2005/03/08 2005, doi: 10.1063/1.1880448.
[622] I. W. Hamley, Small-angle scattering: Theory, instrumentation, data and applications. John Wiley & Sons, 2021.
[623] R. H. Colby, "Structure and linear viscoelasticity of flexible polymer solutions: Comparison of polyelectrolyte and neutral polymer solutions," Rheologica Acta, vol. 49, no. 5, pp. 425-442, 2010.
[624] L. C. Sawyer, D. T. Grubb, and G. F. Meyers, Polymer microscopy, 3rd ed. Springer, 2008.
[625] B. H. Stuart, Infrared spectroscopy: Fundamentals and applications. John Wiley & Sons, 2004.
[626] M. A. Darabi et al., "Skin-Inspired Multifunctional Autonomic-Intrinsic Conductive Self-Healing Hydrogels with Pressure Sensitivity, Stretchability, and 3D Printability," Adv Mater, vol. 29, no. 31, Aug 2017, doi: 10.1002/adma.201700533.
[627] N. U. Khaliq et al., "Pluronics: Intelligent building units for targeted cancer therapy and molecular imaging," Int J Pharm, vol. 556, pp. 30-44, Feb 10 2019, doi: 10.1016/j.ijpharm.2018.11.064.
[628] W. Xie et al., "Injectable and Self-Healing Thermosensitive Magnetic Hydrogel for Asynchronous Control Release of Doxorubicin and Docetaxel to Treat Triple-Negative Breast Cancer," ACS Appl Mater Interfaces, vol. 9, no. 39, pp. 33660-33673, Oct 4 2017, doi: 10.1021/acsami.7b10699.
[629] F. Asghari, M. Samiei, K. Adibkia, A. Akbarzadeh, and S. Davaran, "Biodegradable and biocompatible polymers for tissue engineering application: a review," Artif Cells Nanomed Biotechnol, vol. 45, no. 2, pp. 185-192, Mar 2017, doi: 10.3109/21691401.2016.1146731.
[630] F.-Y. Hsieh, L. Tao, Y. Wei, and S.-h. Hsu, "A novel biodegradable self-healing hydrogel to induce blood capillary formation," NPG Asia Materials, vol. 9, no. 3, pp. e363-e363, 2017/03 2017, doi: 10.1038/am.2017.23.
[631] E. Fallahiarezoudar, M. Ahmadipourroudposht, A. Idris, and N. Mohd Yusof, "A review of: application of synthetic scaffold in tissue engineering heart valves," Mater Sci Eng C Mater Biol Appl, vol. 48, pp. 556-65, Mar 2015, doi: 10.1016/j.msec.2014.12.016.
[632] J. Malda et al., "25th anniversary article: Engineering hydrogels for biofabrication," Adv Mater, vol. 25, no. 36, pp. 5011-28, Sep 25 2013, doi: 10.1002/adma.201302042.
[633] E. Ramirez, S. G. Burillo, C. Barrera-Diaz, G. Roa, and B. Bilyeu, "Use of pH-sensitive polymer hydrogels in lead removal from aqueous solution," J Hazard Mater, vol. 192, no. 2, pp. 432-9, Aug 30 2011, doi: 10.1016/j.jhazmat.2011.04.109.
[634] J. Hu and S. Liu, "Responsive Polymers for Detection and Sensing Applications: Current Status and Future Developments," Macromolecules, vol. 43, no. 20, pp. 8315-8330, 2010/09/17 2010, doi: 10.1021/ma1005815.
[635] T. Shah and S. Halacheva, "Drug-releasing textiles," in Advances in Smart Medical Textiles, ed: Elsevier, 2016, pp. 119-154.
[636] M. Guembe-Garcia et al., "Efficient extraction of textile dyes using reusable acrylic-based smart polymers," J Hazard Mater, vol. 476, p. 135006, Sep 5 2024, doi: 10.1016/j.jhazmat.2024.135006.
[637] Q. Rong, W. Lei, and M. Liu, "Conductive Hydrogels as Smart Materials for Flexible Electronic Devices," Chemistry, vol. 24, no. 64, pp. 16930-16943, Nov 16 2018, doi: 10.1002/chem.201801302.
[638] Y. Shang, J. Wang, T. Ikeda, and L. Jiang, "Bio-inspired liquid crystal actuator materials," Journal of Materials Chemistry C, vol. 7, no. 12, pp. 3413-3428, 2019, doi: 10.1039/c9tc00107g.
[639] A. Dirani et al., "Reversible Photomodulation of the Swelling of Poly(oligo(ethylene glycol) methacrylate) Thermoresponsive Polymer Brushes," Macromolecules, vol. 45, no. 23, pp. 9400-9408, 2012/11/30 2012, doi: 10.1021/ma302106c.
[640] T. K. Chahal, "Recent Advances in Self-Healing Concrete: Mechanisms and Applications," Cement and Concrete Research, 2023. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S0008884623000935.
[641] M. R. Esfahani, "Development of self-healing concrete using various encapsulation techniques: A review," Journal of Building Engineering, 2022. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S2352710222002397.
[642] M. Mostavi and M. Asadi Shamsabadi, "Self-Healing Concrete: A Review of Recent Developments and Future Prospects," Construction and Building Materials, 2022. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S0950061822009950.
[643] R. Siddique, "Bacteria-based self-healing concrete for sustainable construction: A review," Journal of Cleaner Production, 2021. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S0959652621005251.
[644] J. Wang, "Evaluation of microcapsule-based self-healing concrete performance and sustainability," Materials, 2023. [Online]. Available: https://www.mdpi.com/1996-1944/16/7/2587.
[645] C. Santulli, S. I. Patel, G. Jeronimidis, F. J. Davis, and G. R. Mitchell, "Development of smart variable stiffness actuators using polymer hydrogels," Smart Materials and Structures, vol. 14, no. 2, pp. 434-440, 2005/03/22 2005, doi: 10.1088/0964-1726/14/2/018.
[646] V. Bhuvaneswari, "Recent advancements in polymer composites for damage repair applications," in Polymer Composite Systems in Pipeline Repair, ed: Elsevier, 2023, pp. 1-26.
[647] R. Baetens, B. P. Jelle, and A. Gustavsen, "Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review," Solar Energy Materials and Solar Cells, vol. 94, no. 2, pp. 87-105, 2010, doi: 10.1016/j.solmat.2009.08.021.
[648] S. J. Garcia, "Effect of polymer architecture on the intrinsic self-healing character of polymers," European Polymer Journal, vol. 53, pp. 118-125, 2014/04 2014, doi: 10.1016/j.eurpolymj.2014.01.026.
[649] Y. Zhang, S. Wang, X. Li, J. A. Chen, and Y. J. Hong, "High performance siloxane elastomers enable intrinsically stretchable organic electrochemical transistors," Matter, vol. 1, no. 1, pp. 178-189, 2019. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S2451929418303127.
[650] S. Macionis et al., "Does Through‐Space Charge Transfer in Bipolar Hosts Affect the Efficiency of Blue OLEDs?," Advanced Optical Materials, vol. 9, no. 7, p. 2002227, 2021, doi: 10.1002/adom.202002227.
[651] J. Li, L. Xu, and H. Zhang, "Recent advances and future trends in smart polymers: challenges in synthesis, scalability, and cost-effectiveness," Progress in Polymer Science, vol. 129, p. 101568, 2022, doi: 10.1016/j.progpolymsci.2022.101568.
[652] Kamila, "Introduction, Classification and Applications of Smart Materials: An Overview," American Journal of Applied Sciences, vol. 10, no. 8, pp. 876-880, 2013/08/01 2013, doi: 10.3844/ajassp.2013.876.880.
[653] M. Cianchetti, V. Mattoli, B. Mazzolai, C. Laschi, and P. Dario, "A new design methodology of electrostrictive actuators for bio-inspired robotics," Sensors and Actuators B: Chemical, vol. 142, no. 1, pp. 288-297, 2009/10 2009, doi: 10.1016/j.snb.2009.08.039.
[654] D. Kluge, J. C. Singer, J. W. Neubauer, F. Abraham, H. W. Schmidt, and A. Fery, "Influence of the molecular structure and morphology of self-assembled 1,3,5-benzenetrisamide nanofibers on their mechanical properties," Small, vol. 8, no. 16, pp. 2563-70, Aug 20 2012, doi: 10.1002/smll.201200259.
[655] C. Kim, A. Chandrasekaran, S. Jha, and et al., "Machine Learning for Polymer Informatics: Current Status and Future Directions," Chemical Reviews, vol. 123, no. 5, pp. 2416-2472, 2023, doi: 10.1021/acs.chemrev.2c00441.
[656] H.-T. Liu et al., "Enhanced thermoelectric performance of n-type Nb-doped PbTe by compensating resonant level and inducing atomic disorder," Materials Today Physics, vol. 24, p. 100677, 2022, doi: 10.1016/j.mtphys.2022.100677.
[657] Y. Forterre, J. M. Skotheim, J. Dumais, and L. Mahadevan, "How the Venus flytrap snaps," Nature, vol. 433, no. 7024, pp. 421-5, Jan 27 2005, doi: 10.1038/nature03185.
[658] T. Zhang, X. Liu, J. Wang, and et al., "Artificial Intelligence in Smart Polymer Design," Advanced Intelligent Systems, vol. 3, no. 4, p. 2000171, 2021, doi: 10.1002/aisy.202000171.

Full-Text:



Applied Nanomaterials and smart Polymers,

Online ISSN: 2981-0434

Vol. 2, No. 5

 

 

 

Smart Polymers: A Comprehensive Literature Review of Recent Developments and Advancements

 

Ramin Khajavi *

 

Department of Chemical & Polymer Engineering, ST.C, Islamic Azad University, Tehran, Iran 

 

* Corresponding Author: Ramin Khajavi: [e-mail]; [e-mail]

 

https://doi.org/10.61882/ansp.1213849.2.1.1

 

 

Abstract

Smart polymers, also known as stimuli-responsive materials, represent a frontier in materials science, distinguished by their ability to undergo significant, often reversible, changes in their physicochemical properties in response to small external triggers. Drawing inspiration from adaptive biological systems, these polymers are at the heart of innovations across numerous scientific and technological domains. This comprehensive review synthesizes recent advancements in the field, systematically classifying smart polymers based on their primary stimuli, including temperature, pH, light, and mechanical forces. For each class, we delve into the fundamental response mechanisms, from the molecular-level hydrophobic-hydrophilic balance and ionization dynamics to macroscopic phenomena like phase transitions and swelling/deswelling. Key synthesis methodologies, advanced characterization techniques, and the structure-property relationships that govern their behavior are discussed in detail. Furthermore, the review highlights the expanding applications of these intelligent materials in high-impact areas such as targeted drug delivery, regenerative medicine, tissue engineering, biosensing, and soft robotics. Finally, we address the current challenges, including the need for enhanced biocompatibility, precise control over response kinetics, and multifunctionality, while outlining future research directions poised to unlock the full potential of smart polymers in creating the next generation of advanced materials.

 

Keywords: Stimuli-Responsive Materials, Thermoresponsive Polymers, pH-Responsive Polymers, Light-Responsive Polymers, Self-Healing Polymers, Shape Memory Polymers (SMPs), Drug Delivery Systems, Tissue Engineering

 

 

 

 

 

 

 

 

 

 

 

1.Introduction

Smart polymers have emerged as an important class of materials that can undergo reversible changes in response to environmental stimuli. The concept of intelligent materials draws inspiration from natural biological systems that follow a mechanism of sensing, reacting, and learning (Goy et al., 2024). These materials possess the remarkable ability to adapt their molecular

 

structure and function to different external stimuli or environmental changes, mimicking living systems that adapt to their surroundings. This adaptability opens up a wide range of potential applications and piques the interest of researchers and professionals in materials science and related fields. [1, 2].

Over the past few decades, significant research efforts have been directed toward the development of smart polymeric materials for applications in diverse fields such as drug delivery, tissue engineering, sensors, actuators, and environmental remediation. The versatility of these materials stems from their ability to respond to a wide range of stimuli including temperature, pH, light, electrical fields, magnetic fields, biological molecules, and mechanical forces such as compression, tension, or shear [3, 4].

This review presents an extensive analysis of the latest developments in smart polymers, focusing on their design principles, synthesis methodologies, characterization techniques, and various applications. We systematically categorize these materials according to their response triggers and elaborate on their distinctive properties, advantages, and limitations.

 

2. Classification of Smart Polymers

Smart polymers can be classified based on the type of stimuli they respond to. The major categories include Fig.1:

 

 

Figure 1: Classification of smart polymers due to stimule 

 

2.1 Temperature-Responsive Polymers

Temperature-responsive polymers, also known as thermo-responsive polymers, are a class of smart materials that undergo significant physical or chemical changes in response to temperature variations. These materials have gained considerable attention for their potential in biomedical, agricultural, and technological applications due to their ability to provide controlled, dynamic responses fig. 2  [5, 6].

 

Temperature-responsive polymers exhibit a sharp change in properties, such as solubility, morphology, or shape, at specific temperatures. This is often characterized by a lower critical solution temperature (LCST) or upper critical solution temperature (UCST), where the polymer transitions between soluble and insoluble states or undergoes a sol-gel transformation. The LCST represents the temperature below which the polymer is soluble in a given solvent, while above this temperature, phase separation occurs. 

Conversely, UCST polymers are insoluble below a critical temperature and become soluble above it. The phase transition is driven by the delicate balance between polymer-polymer and polymer-solvent interactions, which are temperature-dependent.

 

 

 

At the molecular level, this behavior is governed by changes in the Gibbs free energy of mixing (Eq. 1):

 

        (1)

 

Where  is the Gibbs free energy of mixing,  is the enthalpy of mixing,  is the absolute temperature, and  is the entropy of mixing.[7-13].

 

 

 

Figure 2. transition between temporary annd permanent shape

 

 

 

2.1.1. Types and Classifications

a) LCST-Type Polymers

Poly(N-isopropylacrylamide) (PNIPAM)

PNIPAM is the most extensively studied temperature-responsive polymer, with an LCST around 32 °C in aqueous solution. Its structure contains both hydrophobic isopropyl groups and hydrophilic amide groups, creating an amphiphilic character essential for its thermoresponsive behavior  (Fig.3)[14].

 

Poly(N,N-diethylacrylamide) (PDEAM)

 

 

 

 

PDEAM exhibits an LCST between 25 °C and 35 °C, depending on molecular weight and solution conditions. The presence of diethyl groups provides different hydrophobic-hydrophilic balance compared to PNIPAM (Fig.3) [15].

Poly(oligo(ethylene glycol) methacrylate)s (POEGMA)

These polymers show tunable LCST behavior (20 °C to 90 °C) depending on the length of the ethylene glycol side chains. They offer excellent biocompatibility and resistance to protein adsorption  (Fig.3) [16].

Poly(2-oxazoline)s

This class includes poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline), with LCST values ranging from 25 °C to 100 °C depending on the side chain structure  (Fig.3) [17].

 

 

Figure 3: molecular structure of LCST-Type Polymers

 

b) UCST-Type Polymers

Poly(acrylamide-co-acrylonitrile)

These copolymers exhibit UCST behavior in water, with transition temperatures tunable by adjusting the comonomer ratio [6].

Poly(N-acryloylglycinamide) (PNAGA)

 

 

PNAGA shows UCST behavior in water with a transition temperature around 22 °C, driven by strong intermolecular hydrogen bonding [18].

Polyzwitterions

Certain polyzwitterions, such as poly(3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate), exhibit UCST behavior due to electrostatic interaction [19] (Fig.4).

 

 

Figure 4: molecular structure of UCST-Type Polymers

 

c) Dual Responsive Polymers

Some polymers exhibit both LCST and UCST behavior, creating a miscibility window. Examples include:Poly(ethylene glycol) in water at high temperatures and pressures [20], and certain polyzwitterions under specific conditions[21].

Some examples for thermoresponsive polymers are listed and mentioned in Table 1.

 

Table 1: some thermo responsive polymers

Type of Thermo-Responsive Polymer	Key Features	Example Applications
LCST-type	Becomes insoluble above LCST	Drug delivery, hydrogels [7, 9, 10, 22]
UCST-type	Becomes soluble above UCST	Smart coatings, sensors [7-9]
Shape-memory polymers	Change shape with temperature	Biomedical devices [7]
Multi-responsive polymers	Respond to multiple stimuli (e.g., pH, light)	Advanced drug delivery, tissue engineering [8, 12, 23]

 

 

2.1.2. Mechanisms of Temperature Responsiveness

a) Hydrophobic-Hydrophilic Balance

The primary mechanism for LCST behavior involves the temperature-dependent balance between hydrophobic and hydrophilic interactions. Below the LCST, hydrogen bonding between polymer chains and water molecules dominates, maintaining polymer solubility [24]. As temperature increases:

i.       Water molecules gain kinetic energy

ii.       Hydrogen bonds between polymer and water weaken

 

iii.       Hydrophobic interactions between polymer segments strengthen

iv.       Polymer chains collapse and aggregate

This process can be described by the Flory-Huggins interaction parameter () (Eq. 2-6):

                (2)

where  is the enthalpic contribution and  is the entropic contribution.

 

The Enthalpic Contribution () arises from the change in enthalpy when polymer-solvent contacts are formed, replacing polymer-polymer and solvent-solvent contacts. It is directly proportional to the molar enthalpy of mixing, , and inversely proportional to temperature:

                (3)

Here,  is the universal gas constant and  is the absolute temperature. The Entropic Contribution (): This term accounts for the non-combinatorial or "excess" entropy of mixing, . This includes effects not captured by the ideal entropy of mixing chains, such as the specific ordering of solvent molecules around the polymer segments (e.g., hydrophobic hydration). The entropic parameter is defined as:

        (4)

The negative sign is crucial, as a positive excess entropy (disordering) leads to a negative (favorable) , promoting mixing.

By substituting the definitions from Equations enthalpic and entropic into the fundamental relationship in Equation efeq:additive, we obtain the full and correct expression for the Flory-Huggins interaction parameter:

        (5)

This equation is often written in a simplified linear form, which is useful for analyzing experimental data:

                (6)

where the constant  represents the entropic term () and the constant  represents the enthalpic term () [25].

 

 

b) Hydrogen Bonding Dynamics

Temperature affects the strength and dynamics of hydrogen bonds. For LCST polymers like PNIPAM (Poly(N-isopropylacrylamide)), the breaking of polymer-water hydrogen bonds above the transition temperature is crucial [26] . The process involves:

 

 

i.       Below LCST: Strong polymer-water hydrogen bonds maintain extended chain conformation

ii.       At LCST: Critical balance between hydrogen bonding and hydrophobic interactions

iii.       Above LCST: Intramolecular and intermolecular polymer-polymer interactions dominate

 

c) Entropy Effects

The entropy change during phase transition has two main contributions [27]:

i.       Conformational Entropy

a.       Below LCST: Extended, flexible polymer chains (high conformational entropy)

b.       Above LCST: Collapsed, compact structures (low conformational entropy)

ii.       Solvent Entropy

Water molecules form ordered structures around hydrophobic groups (hydrophobic hydration). Phase separation releases these ordered water molecules, increasing system entropy

 

d) Cooperative Effects

The phase transition often exhibits sharp, cooperative behavior due to [28]:

Propagation effects: Initial collapse facilitates further chain collapse

Intermolecular cooperativity: Aggregation of collapsed chains

Critical phenomena: Near-critical fluctuations enhance transition sharpness

 

e) Molecular Architecture Effects

The polymer architecture significantly influences the transition mechanism [29]:

i.       Linear Polymers

a.       Simple coil-to-globule transition

b.       Transition temperature depends on molecular weight (for low MW)

ii.       Branched/Star Polymers

iii.       Core-shell collapse mechanism

iv.       Often sharper transitions than linear analogues

v.       Cross-linked Networks

vi.       Volume phase transition in hydrogels

vii.       Elastic constraints affect transition kinetics

 

f) Electrostatic Interactions

For charged temperature-responsive polymers, electrostatic effects modulate the transition  [30]:

i.       Charged groups increase hydrophilicity, raising LCST

ii.       Salt addition screens charges, lowering LCST

iii.       pH affects ionization state and thus transition temperature

 

 

2.1.3. Factors Affecting Temperature Responsiveness

These factors are generally Structural Factors: The transition temperature and responsiveness can be tuned by modifying molecular weight, copolymer composition, hydrophilic/hydrophobic balance, and cross-linking density. Advanced polymerization techniques allow precise control over

 

 

these parameters, enabling the design of polymers with tailored responses [9-11, 22, 23]. Some important factors influence the transition temperature and behavior can be listed as below:

i.       Molecular Weight: Generally, LCST decreases with increasing molecular weight until reaching a plateau [31] 

ii.       Concentration: Polymer concentration affects transition temperature and phase diagram [32]

iii.       Additives:

-       Salts (Hofmeister series effects)[33] 

-       Surfactants  [34]

-       Cosolvents [35]

iv.       End Groups: Hydrophobic or hydrophilic end groups can significantly affect LCST

 

2.1.4. Applications

Some applications are listed in table 2 and can be catagorized as below:

i. Controlled drug delivery systems - Thermo-responsive polymers enable controlled, site-specific drug release, minimizing side effects and improving efficacy. Nanogels and nanoparticles can encapsulate drugs and release them in response to temperature changes, as demonstrated with doxorubicin and antimicrobial agents.

ii. Tissue Engineering- These polymers serve as scaffolds that support cell growth and can be engineered to mimic natural tissue responses

iii. Other Uses- Applications extend to bioseparation, gene therapy, imaging, and even agrochemical delivery in plants, where temperature triggers the release of protective agents [9-12, 36-41].

 

2.1.5. Design Challenges and Future Directions

Tuning Responsiveness: Achieving precise control over transition temperatures and multi-stimuli responsiveness remains a key challenge. Copolymerization and advanced synthesis methods are being developed to address this  [8, 10, 11, 22, 23].

Biocompatibility and Stability: Ensuring that these polymers are safe and stable in biological environments is critical for clinical and agricultural applications   [9, 10, 22].

Expanding Applications: Research is ongoing to develop polymers with dual or multi-temperature responsiveness and to integrate additional stimuli (e.g., light, pH) for more sophisticated smart materials     [8, 12, 23].

 

Temperature-responsive polymers are versatile smart materials that undergo significant changes in response to temperature, enabling a wide range of applications, especially in drug delivery and tissue engineering. Their properties can be finely tuned through structural modifications, and ongoing research aims to enhance their responsiveness, biocompatibility, and multifunctionality for advanced biomedical and technological uses.

Poly(N-isopropylacrylamide) (PNIPAAm) is one of the most extensively studied thermoresponsive polymers with an LCST around 32°C, which is close to physiological temperature [42]. Below the LCST, PNIPAAm chains are hydrated and exist in an extended conformation, while above the LCST, they undergo a phase transition to a collapsed, hydrophobic state due to the disruption of hydrogen bonds with water molecules [43].

Other important thermoresponsive polymers include poly(N-vinylcaprolactam) (PVCL), pluronics (triblock copolymers of poly(ethylene oxide) and poly(propylene oxide)), and elastin-like polypeptides (ELPs)  [44, 45]. These polymers have been widely employed in controlled drug delivery systems, tissue engineering scaffolds, and smart textiles.

Recent advancements in thermoresponsive polymers have focused on developing materials with tunable LCST/UCST values, improved mechanical properties, and multifunctional capabilities. For instance, copolymerization strategies have been employed to incorporate additional responsive elements or bioactive moieties into thermoresponsive polymers [8, 46].

 

 

 

Table 2: Temperature-Responsive Polymers applivcations 

Polymer Type	Key Features	Applications	Citation
Poly(N-isopropylacrylamide) (PNIPAAm)	LCST around 32°C; reversible hydrophilic-hydrophobic transition; excellent biocompatibility	Drug delivery systems; cell sheet engineering; tissue scaffolds; biosensors	[42, 47-54]
Poly(N-vinylcaprolactam) (PVCL)	LCST between 30-35°C; non-ionic; lower cytotoxicity than PNIPAAm; pH-independent phase transition	Controlled drug release; protein separation; textile finishing; biosensors	[55-62]
Elastin-like polypeptides (ELPs)	Bioderived; precise LCST control through sequence design; biodegradable; stimuli-responsive	Protein purification; targeted drug delivery; tissue engineering; biosensors	[63-72]
Pluronic block copolymers (PEO-PPO-PEO)	Amphiphilic triblock structure; thermoreversible gelation; micelle formation; versatile LCST range	Injectable hydrogels; sustained drug delivery; gene therapy; tissue engineering	[36, 44, 73-79]
Poly(oligoethylene glycol methacrylate) (POEGMA)	Tunable LCST through comonomer composition; excellent biocompatibility; narrow phase transition	Protein conjugation; smart surfaces; biosensors; drug delivery	[80-90]
Poly(2-oxazoline)s	Tunable LCST through side-chain modification; biocompatible; narrow phase transition	Nanomedicine; drug delivery; tissue engineering; anti-fouling coatings	[91-98]
Poly(N-acryloylglycinamide) (PNAGA)	UCST behavior in aqueous solution; stability against salt addition; sharp phase transition	Controlled release; protein separations; thermal actuators; biomedical devices	[99-103]
Temperature-responsive polymer nanocomposites	Enhanced mechanical properties; multi-responsive behavior; improved thermal conductivity	Smart textiles; shape-changing actuators; sensors; 4D printing	[104-114]

 

 

 

 

 

 

2.2. pH-Responsive Polymers

2.2.1. Introduction

pH-responsive polymers, also known as pH-sensitive or pH-triggered polymers, are a class of stimuli-responsive materials that undergo significant physicochemical changes in response to variations in environmental pH [4]. These smart materials have garnered substantial attention due to their potential applications in drug delivery, biosensing, tissue engineering, and various biomedical applications [115-118] (Fig 3).

 

pH-responsive polymers contain ionizable functional groups that can accept or donate protons in response to environmental pH changes. The ionization state of these groups directly affects the polymer’s conformation, solubility, and swelling behavior [119]. The fundamental principle underlying pH-responsiveness is the Henderson-Hasselbalch equation Eq. 7:

 

                (7)

 

where  is the acid dissociation constant,  is the concentration of the conjugate base, and  is the concentration of the weak acid.

The Henderson-Hasselbalch equation is a cornerstone of acid-base chemistry and is fundamental to understanding the behavior of pH-responsive polymers. This equation provides a direct mathematical link between the pH of a buffered solution, the intrinsic acidity of the active functional group (given by its ), and the ratio of its deprotonated to protonated forms. The pH is the independent variable, representing the external environmental condition. It is defined as the negative base-10 logarithm of the hydrogen ion activity, approximated by its concentration :

 

                (8)

 

For a pH-responsive polymer, a change in the solution’s pH is the trigger that initiates a macroscopic change in the material’s properties. The  (the negative logarithm of the acid dissociation constant, ) is an intrinsic, constant value for a given acidic functional group. It defines the pH at which the system is most sensitive to change. At the precise moment when  the concentrations of the protonated and deprotonated forms are equal: . Consequently, the ratio term , and since , the equation simplifies to . This point represents the midpoint of the polymer’s transition from a collapsed to a swollen state (or vice-versa).

 and represent the molar concentrations of the polymer’s functional groups in their two possible states:

-        (Protonated Acid): This is the concentration of the functional groups in their neutral, protonated state (e.g., carboxylic acid, ). In this form, the polymer chains are typically less soluble, compact, and dominated by hydrophobic interactions or intramolecular hydrogen bonding.

 

 

 

-        (Deprotonated Conjugate Base): This is the concentration of the functional groups in their charged, deprotonated state (e.g., carboxylate anion, ). The presence of these charges leads to strong electrostatic repulsion along the polymer backbone, causing the chain to expand and become hydrophilic, leading to swelling and dissolution.

The term  quantifies the state of the polymer system in response to the pH.

-       If , the log term is negative, indicating . The polymer is predominantly in its collapsed, protonated state.

-       If , the log term is positive, indicating . The polymer is predominantly in its swollen, deprotonated (charged) state.

 

Application of Henderson-Hasselbalch equation to pH-Responsive Polymers

The Henderson-Hasselbalch equation (Eq. 7) governs the behavior of both polyacids and polybases:

 

Polyacids (Anionic Polymers)

Examples include Poly (acrylic acid) (PAA) and Poly (methacrylic acid) (PMAA). For these polymers, the HA form is the neutral  group and the A form is the anionic  group.

 

 

As the pH rises above the polymer’s  (around 4.5-5.0), the polymer transitions from a collapsed globule to a swollen, hydrated coil due to electrostatic repulsion.

Polybases (Cationic Polymers)

Examples include Poly (dimethylaminoethyl methacrylate) (PDMAEMA) and Chitosan. For these polymers, the equation is applied to the conjugate acid equilibrium. For polybases, it’s often more intuitive to think in terms of pKb or the pKa of the conjugate acid (BH+). The principle is the same. At low pH (below its pKa≈7.5), the amine groups are protonated (BH+). The polymer is positively charged, expanded, and soluble.

The Henderson-Hasselbalch equation can be written for the conjugate acid, . Here,  (the protonated amine) is the charged "acid" form, and  (the neutral amine) is the "base" form. At low pH (below the  of the conjugate acid,  for PDMAEMA), the polymer is protonated, positively charged (), and soluble. As the pH is raised, it deprotonates to its neutral, hydrophobica form () and collapses. In summary, the Henderson-Hasselbalch equation provides the quantitative framework for predicting and designing the pH at which a smart polymer will undergo its functional transition.

 

2.2.2. Classification of pH-Responsive Polymers

Generally, these polymers can be broadly classified into two categories: polyacids (containing carboxylic or sulfonic acid groups) and polybases (containing amine groups) [120]. Polyacids, such as poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), remain unionized at low pH values but become increasingly ionized as the pH increases above their pKa values, leading to chain expansion due to electrostatic repulsion between negatively charged groups [121].

 

Conversely, polybases like poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(ethylenimine) (PEI) are ionized at low pH and become deprotonated as the pH increases [122]. Indetail catagorization of pH-Responsive Polymers can be expressed as below:

 

Polyacids (Anionic Polymers)

Polyacids contain acidic groups such as carboxylic acid (-COOH), sulfonic acid (-SOH), or phosphoric acid (-POH) groups. These polymers are protonated at low pH and become deprotonated and negatively charged at high pH [123].

Examples  (Fig. 4  ) :

i.       Poly(acrylic acid) (PAA)

ii.       Poly(methacrylic acid) (PMAA)

iii.       Poly(L-glutamic acid) (PGA)

iv.       Poly(aspartic acid) (PASP)

 

 

 

 

Figure 4 : Polyacids pH sensetive polymers

 

Polybases (Cationic Polymers)

Polybases contain basic groups such as amines, which become protonated and positively charged at low pH and neutral at high pH [124].

Examples (Fig. 5 ):

 

i.       Poly(dimethylaminoethyl methacrylate) (PDMAEMA)

ii.       Poly(diethylaminoethyl methacrylate) (PDEAEMA)

 

iii.       Chitosan

iv.       Poly(L-lysine) (PLL)

v.       Polyethylenimine (PEI)

 

 

Figure 5  :  Polybases examples 

 

 

 

Polyampholytes

Polyampholytes contain both acidic and basic groups within the same polymer chain, exhibiting complex pH-dependent behavior with isoelectric points where the net charge is zero [125].

Examples (Fig. 6 ):

i.       Proteins and polypeptides

ii.       Poly(methacrylic acid-co-dimethylaminoethyl methacrylate)

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6: Polyampholytes examples

 

 

pH-Responsive Hydrogels

These are three-dimensional networks that can absorb large amounts of water and exhibit dramatic volume changes in response to pH variations [126].

Some of pH-Responsive Polymers are presented in table 3.

 

Table3- pH-Responsive Polymers

Polymer Type	Key Features	Applications	Citation
Poly(acrylic acid) (PAA)	Carboxylic acid pendant groups; transitions from collapsed to expanded state above pH 4-5; excellent pH sensitivity	Oral drug delivery; colon-targeted release; sensors; controlled release	[120, 121, 127-134]
Poly(methacrylic acid) (PMAA)	Stronger acid than PAA; pH-dependent swelling; versatile functionalization capacity	Intestinal drug delivery; stimuli-responsive membranes; biosensors; controlled release	[132, 135-143]
Chitosan-based pH-responsive systems	Natural polymer; protonated at acidic pH; biodegradable; biocompatible; mucoadhesive	Oral drug delivery; tissue engineering; wound healing; gene delivery	[116, 144-152]
Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)	Protonated at acidic pH; hydrophilic-hydrophobic transition; strong buffering capacity	Gene delivery; antimicrobial materials; sensors; controlled release	[153].
Poly(ethylenimine) (PEI)	High cationic charge density; strong buffering capacity; "proton sponge" effect	Gene transfection; antimicrobial coatings; water treatment; carbon capture	[154]
Poly(histidine)	Imidazole groups responsive to physiological pH range (6.0-7.4); endosomal escape capability	Targeted anticancer drug delivery; gene therapy; intracellular delivery	[155]
Block copolymers with pH-responsive segments	Self-assembly into micelles/vesicles; multi-responsive behavior; tunable release properties	Tumor-targeted drug delivery; intracellular delivery; diagnostic imaging	[119]
Poly(acrylamide-co-methacrylic acid)	Tunable pH response through copolymer composition; high swelling capacity; mechanical stability	Controlled drug release; tissue engineering; agricultural applications	[156]

 

 

2.2.3. Mechanisms of pH-Responsiveness polymers

The macroscopic changes observed in pH-responsive polymers, such as swelling, collapse, or sol-gel transitions, are driven by a complex interplay of physicochemical phenomena at the molecular level. The primary trigger for these changes is the protonation or deprotonation of ionizable functional groups along the polymer backbone as the environmental pH crosses the group’s characteristic  value. This ionization event initiates several interconnected mechanisms, which are detailed below [157].

 

Ionization-Induced Conformational Changes

The fundamental mechanism governing pH-responsiveness is the alteration of the polymer’s conformation due to changes in its ionization state. As the pH shifts, the following effects collectively determine the polymer’s structure and solubility:

-       Electrostatic Repulsion: When the functional groups become ionized (e.g., carboxylic acids forming carboxylates, ), the resulting like charges along the polymer chain repel each other. This intramolecular repulsion overcomes cohesive forces, forcing the polymer chains to uncoil and adopt a more expanded, hydrophilic conformation.

-       Osmotic Pressure: The ionization of polymer chains creates a high concentration of fixed charges within the polymer network or hydrogel (FIG 7). To maintain electroneutrality, mobile counter-ions from the surrounding solution migrate into the polymer domain. This influx of ions dramatically increases the internal ion concentration, generating a significant osmotic pressure difference between the interior of the polymer and the bulk solution. The resulting osmotic swelling pressure drives water into the network, causing it to expand.

 

Figure 7 : Osmotic Pressure in inoized polymer network

-       Changes in Hydration: The hydration state of the functional groups is highly dependent on their ionization. Ionized groups (e.g., , ) are significantly more hydrophilic and form stronger hydrogen bonds with water molecules than their neutral counterparts (e.g., , ). This enhanced hydration contributes to chain expansion and increased solubility in aqueous media.

Swelling/Deswelling Mechanisms in Hydrogels

For crosslinked pH-responsive networks (hydrogels), the balance between these expansive forces and the elastic retractive force of the polymer chains determines the equilibrium swelling behavior. The swelling ratio, , can be quantitatively described by the Flory-Rehner theory, which was extended by Peppas and colleagues to account for the ionic contribution. The modified equation is given as Eq.9 [158]:

                (9)

 

where  is the volume swelling ratio,  is the polymer volume fraction in the swollen state,  is the effective crosslinking density,  is the molar volume of the solvent (water),  is the Flory-

 

Huggins polymer-solvent interaction parameter,  is the charge per pendant group,  is the volume of a repeating unit, and  is the ionic strength of the external solution [158]. This equation models how the degree of ionization and external ionic strength directly influence the hydrogel’s equilibrium volume.

Sol-Gel Transitions

pH changes can also induce reversible transitions between a solution state (sol) and a solid-like state (gel). These transitions are typically mediated by the pH-dependent formation or disruption of non-covalent crosslinks, including:

-       Hydrogen Bonding: Shifts in pH can alter the ability of functional groups to act as hydrogen bond donors or acceptors, leading to the formation or breakage of physical crosslinks that define the gel state.

-       Ionic Crosslinking: In systems containing both positive and negative charges (polyampholytes) or in mixtures of oppositely charged polymers, pH changes can modulate electrostatic attractions, leading to the formation of ionic crosslinks and subsequent gelation.

-       Hydrophobic-Hydrophilic Balance: As described by [157] & Gutowska (2002), the protonation/deprotonation of side chains can switch a polymer segment from being hydrophilic to hydrophobic, promoting aggregation and physical crosslinking through hydrophobic interactions, which can trigger gel formation .

Phase Separation Mechanisms

In polymer solutions (non-crosslinked systems), pH changes can induce macroscopic phase separation, where the polymer precipitates out of the solution. This behavior is often linked to the modulation of the polymer’s critical solution temperature:

-       LCST (Lower Critical Solution Temperature) Behavior: For many polymers, such as those containing tertiary amine groups (e.g., PDMAEMA), the ionization state directly influences the LCST. In their protonated (charged) state at low pH, these polymers are highly soluble. As the pH increases, deprotonation renders them more hydrophobic, causing the LCST to decrease. If the LCST drops below the system’s temperature, the polymer will phase separate.

-       UCST (Upper Critical Solution Temperature) Behavior: Conversely, for polymers that become more soluble upon heating, the ionization state can shift the  [159].

 

 

2.2.4. Temperature Responsiveness in pH-Responsive Polymers

Many pH-responsive polymers also exhibit temperature-responsive behavior, creating dual-responsive systems. The mechanisms of temperature responsiveness include:

 

 

 

Hydrophobic-Hydrophilic Balance

Temperature changes affect the hydration of polymer chains and the strength of hydrogen bonds. At the lower critical solution temperature (LCST), polymers undergo a coil-to-globule transition due to:

i.       Disruption of polymer-water hydrogen bonds

ii.       Enhanced hydrophobic interactions

iii.       Entropic effects favoring water molecule release [14]

 

Dual pH/Temperature Response Mechanisms

 

The synergistic interplay between pH and temperature responsiveness in dual-stimuli polymers arises from the direct influence of one stimulus on the polymer’s response to the other. This coupling manifests primarily through two key physicochemical mechanisms:

1)       Ionization-Dependent Lower Critical Solution Temperature (LCST): The phase transition temperature of a thermo-responsive polymer is highly sensitive to its overall hydrophilicity. For polymers containing ionizable groups (e.g., carboxylic acids or amines), the degree of ionization () directly alters the polymer’s charge density and hydration state. As the polymer becomes more charged (ionized), its hydrophilicity increases, which in turn raises its LCST. This relationship can be empirically described by the following linear approximation Eq.10:

                (10)

       where  is the intrinsic LCST of the polymer in its non-ionized state,  is the observed LCST at a given pH,  is an empirical constant that reflects the sensitivity of the LCST to ionization, and  is the degree of ionization, which is a function of pH [160]. This equation illustrates how pH can be used to precisely tune the temperature at which the polymer undergoes its phase transition.

2)       Temperature-Modulated pKa: Conversely, the dissociation constant () of the ionizable groups within the polymer is not fixed but is dependent on temperature. This relationship is governed by the van’t Hoff equation, which describes the change in an equilibrium constant with temperature. For the ionization process, this can be expressed as Eq.11:

                (11)

       where  is the standard enthalpy of ionization for the functional group,  is the universal gas constant, and  is the absolute temperature [161]. This dependency means that a change in temperature can shift the pH range over which the polymer is responsive, effectively altering its pH-triggered behavior.

Examples of Dual-Responsive Polymers

The rational design of polymers incorporating both pH- and temperature-sensitive moieties has led to a variety of sophisticated materials. Prominent examples include:

-       Poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)): This widely studied copolymer integrates the thermo-responsive NIPAAm units (providing LCST behavior) with the pH-responsive AAc units (Fig 7)  . At low pH, the AAc groups are protonated and less hydrophilic, resulting in a lower LCST. At high pH, the deprotonated carboxylate groups increase hydrophilicity, significantly raising the LCST.

 

Figure 7   : P(NIPAAm-co-AAc)

-       Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA): This polymer is intrinsically dual-responsive (Fig. 8  ) . The tertiary amine groups provide pH sensitivity (protonating at acidic pH), while the polymer backbone exhibits an LCST around 50°C in its neutral state.

 

 

Figure 8   : PDMAEMA

-       Chitosan Derivatives: As a natural polysaccharide, chitosan provides a biocompatible and biodegradable backbone. Its primary amine groups confer pH responsiveness. By grafting thermo-responsive polymers like PNIPAAm onto the chitosan backbone, researchers have created dual-responsive systems with significant potential in biomedical applications [123, 162]

2.2.5. Applications Leveraging pH and Temperature Responsiveness

The unique ability of pH and temperature dual-responsive polymers to undergo reversible changes in response to multiple stimuli has opened numerous opportunities across biomedical, environmental, and industrial applications. These smart materials can be precisely engineered to

 

respond to physiological conditions, making them particularly valuable for therapeutic and diagnostic applications [123, 163].

Controlled Drug Delivery: Targeting Specific pH Environments with Temperature-Triggered Release

pH and temperature dual-responsive polymers have revolutionized targeted drug delivery by exploiting the unique microenvironments of diseased tissues. The tumor microenvironment, characterized by acidic pH (6.5-7.2) compared to normal tissues (pH 7.4) and elevated temperatures due to enhanced metabolism, provides ideal conditions for selective drug release [164, 165]. Poly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAAm-co-AA)] copolymers have been extensively studied for cancer therapy, demonstrating enhanced drug accumulation in tumor tissues through pH-triggered swelling and temperature-induced phase transitions [166, 167].

In gastrointestinal drug delivery, pH-responsive polymers protect drugs from the acidic stomach environment (pH 1-3) and enable controlled release in the intestinal tract (pH 6-8). Eudragit® polymers, based on methacrylic acid copolymers, have been successfully commercialized for enteric coating applications [168]. Recent advances include the development of multi-responsive nanocarriers incorporating poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) that respond to both pH and temperature changes throughout the GI tract, improving oral bioavailability of protein drugs  [169, 170],

The integration of pH and temperature responsiveness has enabled sophisticated drug delivery systems with programmable release profiles. Core-shell nanoparticles with pH-sensitive cores and thermoresponsive shells demonstrate sequential drug release triggered by environmental changes [171]. These systems have shown particular promise for combination therapy, where different drugs can be released at specific sites and times based on local pH and temperature conditions [172] [173]

Smart Hydrogels: Self-Regulating Materials for Wound Healing and Tissue Engineering

pH and temperature-responsive hydrogels represent a significant advancement in regenerative medicine, offering dynamic materials that can adapt to physiological changes during healing processes. Wound environments typically exhibit pH variations from 5.5-8.5 depending on the healing stage, while inflammation causes local temperature increases  [174, 175], Smart hydrogels based on chitosan-g-poly(N-isopropylacrylamide) have demonstrated excellent wound healing properties by modulating drug release and moisture retention in response to wound pH and temperature  [176, 177],

In tissue engineering applications, dual-responsive hydrogels serve as dynamic scaffolds that can mimic the natural extracellular matrix. Injectable hydrogels based on poly(ethylene glycol)-b-poly(L-glutamic acid) block copolymers undergo sol-gel transitions at physiological temperature

 

and pH, enabling minimally invasive delivery while providing mechanical support for cell growth  [178, 179], These materials have shown promise in cartilage regeneration, where the pH-responsive components facilitate nutrient transport while temperature sensitivity enables in situ gelation  [180, 181].

Recent developments include self-healing hydrogels that respond to pH and temperature changes to autonomously repair damage. Poly(acrylic acid)-g-poly(N-isopropylacrylamide) hydrogels crosslinked through dynamic covalent bonds demonstrate rapid self-healing at physiological conditions, making them ideal for load-bearing tissue engineering applications  [182, 183], These materials have shown enhanced cell viability and proliferation compared to static hydrogels, attributed to their dynamic mechanical properties [184].

Biosensors: Dual-Responsive Systems for Enhanced Sensitivity and Selectivity

The integration of pH and temperature responsiveness in biosensor design has significantly improved detection sensitivity and selectivity for various biomarkers. Microcantilever sensors functionalized with pH and temperature-responsive polymers demonstrate enhanced mechanical response to target binding, with detection limits in the picomolar range (Bashir et al., 2010; Tamayo et al., 2013). Poly(methacrylic acid-co-N-isopropylacrylamide) brushes grafted on sensor surfaces undergo conformational changes that amplify signal transduction, enabling label-free detection of proteins and nucleic acids   [185, 186].

Optical biosensors incorporating dual-responsive polymers have shown particular promise for continuous monitoring applications. Photonic crystals embedded in pH and temperature-responsive hydrogels exhibit reversible color changes in response to analyte binding, providing visual readouts without external power sources (Hu et al., 2012; Yetisen et al., 2016). These sensors have been successfully applied to glucose monitoring, where enzyme-catalyzed reactions create local pH changes that, combined with temperature variations, produce distinct optical signatures [187, 188].

Electrochemical biosensors utilizing dual-responsive polymer coatings demonstrate improved selectivity through controlled permeability. Poly(N-isopropylacrylamide-co-allylamine) films on electrode surfaces act as molecular gates, regulating analyte access based on environmental conditions [189]. This approach has enabled selective detection of neurotransmitters in complex biological matrices, with applications in neurological disorder diagnosis  [190, 191].

Separation Technologies: pH and Temperature-Controlled Membrane Permeability

Dual-responsive polymers have revolutionized membrane separation technologies by enabling dynamic control over permeability and selectivity. Membranes functionalized with poly(N-isopropylacrylamide-co-acrylic acid) demonstrate reversible pore size changes in response to pH and temperature, allowing for tunable separation of proteins and nanoparticles (Wandera et al.,

 

2010; Zhao et al., 2011). These smart membranes have shown 10-fold changes in permeability between different pH and temperature conditions, significantly improving separation efficiency  [192, 193].

In water treatment applications, pH and temperature-responsive membranes offer energy-efficient solutions for removing contaminants. Poly(vinylidene fluoride) membranes modified with dual-responsive copolymers demonstrate self-cleaning properties through stimuli-triggered surface reorganization, reducing fouling by up to 90% compared to conventional membranes  [194, 195]. These systems have shown particular effectiveness in treating industrial wastewater with varying pH and temperature conditions [196, 197].

Advanced separation systems incorporating magnetic nanoparticles coated with pH and temperature-responsive polymers enable remote-controlled separation processes. These materials combine the advantages of magnetic separation with stimuli-responsive selectivity, achieving high recovery rates for valuable biomolecules and rare earth elements [198, 199]. Recent developments include continuous-flow separation systems that automatically adjust conditions based on feed composition, demonstrating the potential for autonomous operation  [200, 201].

Challenges of pH and Temperature-Responsive Polymers

Despite their tremendous potential, pH and temperature dual-responsive polymers face several significant challenges that must be addressed for widespread clinical and industrial implementation.

Material Design and Synthesis Challenges

The precise control over polymer composition and architecture required for predictable dual-responsive behavior remains a significant challenge. Achieving narrow molecular weight distributions and uniform functionality distribution is crucial but difficult, particularly for complex architectures like star polymers or dendrimers [202, 203]. Batch-to-batch reproducibility issues can lead to inconsistent performance, particularly problematic for biomedical applications requiring regulatory approval [204].

The incorporation of multiple responsive moieties often results in competing effects that complicate the response profile. For instance, increasing the content of pH-responsive groups may interfere with temperature-responsive behavior, requiring careful optimization of copolymer composition [21, 205] . Additionally, the synthesis of biocompatible and biodegradable dual-responsive polymers with appropriate mechanical properties remains challenging, as many responsive polymers are based on non-degradable backbones [206].

 

 

 

Response Kinetics and Reversibility

The response time of dual-responsive polymers to environmental changes can be too slow for certain applications, particularly in drug delivery where rapid release may be required. The diffusion-limited nature of polymer chain reorganization means that bulk materials may take hours to fully respond to stimuli  [207, 208] (Yoshida et al., 2013; Stuart et al., 2010). While nanostructured materials can improve response times, they introduce additional complexity in terms of stability and manufacturing [209].

Reversibility and cycling stability represent another major challenge. Repeated pH and temperature cycling can lead to polymer degradation, irreversible aggregation, or loss of responsive behavior  [210, 211]. This is particularly problematic for long-term implantable devices or reusable separation membranes. The hysteresis observed in many dual-responsive systems further complicates their application in precision-controlled environments  [212].

Biological and Environmental Compatibility

For biomedical applications, ensuring biocompatibility while maintaining responsive behavior is challenging. Many pH-responsive polymers contain charged groups that can interact non-specifically with proteins and cells, potentially causing cytotoxicity or immune responses [213, 214]. The lower critical solution temperature (LCST) of many thermoresponsive polymers is close to body temperature, making it difficult to achieve sharp transitions under physiological conditions without incorporating potentially toxic comonomers [215].

The complex biological environment presents additional challenges, including protein adsorption, enzymatic degradation, and varying ionic strength effects that can alter polymer responsiveness [216, 217]. The presence of salts and proteins in biological fluids can significantly shift transition temperatures and pH responses, requiring careful calibration for each specific application [218].

Scalability and Manufacturing Considerations

Scaling up the synthesis of dual-responsive polymers from laboratory to industrial scale presents significant challenges. Controlled polymerization techniques that produce well-defined polymers often require expensive catalysts, inert atmospheres, and precise temperature control, making large-scale production costly  [219, 220]. Purification processes to remove residual monomers, catalysts, and byproducts can be complex and may alter polymer properties.

The processing of dual-responsive polymers into useful forms (films, particles, fibers) while maintaining their responsive behavior is technically demanding. Conventional processing methods may expose polymers to conditions that trigger unwanted transitions or cause degradation   [221]. Additionally, ensuring long-term storage stability of these materials, particularly in hydrated forms, remains a significant challenge for commercial applications [222].

 

Regulatory and Standardization Challenges

The lack of standardized characterization methods for dual-responsive polymers complicates regulatory approval and quality control. Different research groups often use varying protocols to assess responsive behavior, making it difficult to compare materials or establish performance benchmarks [223]. For medical applications, demonstrating consistent performance across the range of physiological conditions encountered in diverse patient populations is particularly challenging [224].

The regulatory pathway for dual-responsive polymer-based medical devices and drug delivery systems remain unclear in many jurisdictions. The dynamic nature of these materials challenges traditional regulatory frameworks designed for static materials [225]. Establishing appropriate safety margins and failure modes for materials that undergo significant property changes in response to environmental stimuli requires new approaches to risk assessment [226].

Controlled Drug Delivery: Targeting specific pH environments (e.g., tumors, GI tract) with temperature-triggered release

Smart Hydrogels: Self-regulating materials for wound healing and tissue engineering

Biosensors: Dual-responsive systems for enhanced sensitivity and selectivity

Separation Technologies: pH and temperature-controlled membrane permeability

 

Conclusion

Recent advances in pH-responsive polymers have explored their applications in targeted drug delivery, particularly for cancer therapy, where the acidic tumor microenvironment can be exploited for triggered release .The development of pH-responsive nanomaterials has gained significant attention due to their ability to improve the efficiency of drug delivery in vivo, allow targeted drug delivery, and reduce adverse drug reactions [227-230].

pH-responsive polymers represent a versatile class of smart materials with complex mechanisms governing their behavior. The integration of temperature responsiveness adds another dimension of control, enabling sophisticated applications in biotechnology and medicine. Understanding the fundamental mechanisms of both pH and temperature responses is crucial for the rational design of next-generation responsive materials.

 

 

 

2.3 Light-Responsive Polymers

Light-responsive polymers represent a fascinating class of smart materials that undergo reversible or irreversible changes in their physical, chemical, or mechanical properties upon exposure to electromagnetic radiation [231]. These materials have emerged as crucial components in advanced technologies ranging from drug delivery systems to optical data storage, soft robotics, and biomimetic devices [232]. The ability to control polymer behavior with light offers unprecedented advantages including spatial and temporal precision, remote activation, and minimal invasiveness, making these materials particularly attractive for biomedical applications [233].

The development of light-responsive polymers has been inspired by nature's sophisticated photochemical systems, from the rhodopsin proteins enabling vision to the phytochromes 

 

controlling plant growth [234]. By incorporating photoactive chromophores into synthetic polymer chains, scientists have created materials that can mimic these biological processes while offering enhanced stability and tunability [235].

Here are some key examples and concepts from nature that are analogous to synthetic light-responsive polymers:

 

Photoactive Proteins

These are perhaps the most direct natural analogs to light-responsive polymers. Proteins are natural polymers (chains of amino acids), and many of them have evolved to respond to light.

i.       Rhodopsin (and other visual pigments): 

Found in the eyes of animals, rhodopsin is a classic example of a photoactive protein [236]. It consists of a protein (opsin) bound to a light-sensitive chromophore (retinal) [237]. When retinal absorbs light, it undergoes a rapid cis-trans isomerization, which in turn causes a conformational change in the opsin protein [238]. This shape change initiates a signaling cascade that leads to vision, representing a perfect example of light-triggered conformational change in a polymer  [239, 240] (Fig. 9).

 

 

 

Figure 9 : Rhodopsin

 

 

 

 

 

ii.       Phytochromes: Found in plants, bacteria, and fungi, phytochromes are photoreceptors that sense red and far-red light [241, 242]. They exist in two interconvertible forms (Pr and Pfr) [243]. Light absorption triggers a conformational change that shifts the equilibrium between these forms, allowing the organism to sense light quality and quantity, influencing processes like germination, flowering, and shade avoidance   [244-246](Fig.10 ).

 

 

Figure 10  :   Phytochromes

 

 

iii.       Photosystem I and Photosystem II (in photosynthesis): These protein complexes embedded in membranes are central to photosynthesis [247]. They contain pigments (like chlorophyll) that capture light energy [248]. This energy is then used to drive electron transport and ultimately produce ATP and NADPH [249]. While not directly “polymeric” in the same way, the complex interplay of proteins and chromophores to convert light energy into chemical energy is a highly sophisticated light-responsive system [250, 251] (Fig. 11 ).

 

 

Figure 11 :Photosystem I and Photosystem II

 

 

 

iv.       Bacteriorhodopsin and Halorhodopsin: Found in archaea, these are light-driven ion pumps [237, 252]. When they absorb light, they undergo confo rmational changes that result in the vectorial transport of protons or chloride ions across the cell membrane, generating an electrochemical gradient [253, 254].

v.       Light-oxygen-voltage (LOV) domains: These are found in many organisms and are involved in light sensing  [255, 256]. They contain a flavin chromophore that forms a reversible covalent bond with a cysteine residue upon blue light illumination [257]. This covalent bond formation induces conformational changes in the protein, which can regulate various cellular processes   [258, 259].

Melanin and other Pigments

While not typically considered “polymers” in the same context as synthetic ones, melanin (a complex polymer of phenolic and indole units, Fig.12    ) is a well-known light-responsive pigment in animals    [260, 261].

 

 

 

Figure 12   : The esteimated structure of melanin

 

 

i. UV Protection

Melanin absorbs UV radiation, converting it into heat and dissipating it, thereby protecting cells from DNA damage [262, 263]. Its formation (tanning) is a light-induced process   [264, 265].

ii. Camouflage and Display

In some animals (e.g., chameleons, cephalopods), pigments can rapidly change their dispersion or aggregation in response to light signals, allowing for dynamic color changes for camouflage or communication [266-268].

Natural Photocrosslinking/Photopolymerization

While synthetic photopolymers often involve the light-induced crosslinking of monomers to form a solid, nature also has examples where light plays a role in modifying or forming biological structures  [269, 270]:

i. Lignin Formation

Lignin, a complex aromatic polymer in plant cell walls, undergoes free-radical polymerization during its formation  [271, 272]. While not solely light-driven, light (specifically UV radiation) can influence the generation of radicals that initiate or participate in lignin polymerization in certain contexts [273, 274].

ii. Certain enzymatic reactions

Some enzymes are light-activated and can catalyze polymerization or crosslinking reactions in a light-dependent manner. This is more about light activating a catalytic process rather than the direct photopolymerization of the “monomers” themselves  ([275, 276],

Light-secretive polymers, often referred to as light-sensitive or photo-editable polymers, represent a rapidly evolving class of materials capable of storing, revealing, and erasing information at the

 

 

molecular level through exposure to specific wavelengths of light  [277, 278]. Recent research has demonstrated that these polymers can act as molecular-scale “invisible ink,” with their monomer sequences transformed by light to encode, decode, or erase messages  [279, 280]. For example, scientists have shown that information such as chemical symbols can be written and later altered or removed by controlled light exposure, offering a new paradigm for secure information storage and anti-counterfeiting technologies [281, 282] . The ability to manipulate the information content of polymers using light not only mimics biological information systems like DNA but also opens avenues for advanced data storage and dynamic material design  [283, 284]. The broader field of light-responsive polymers encompasses a variety of photochemical processes, including bond formation, degradation, and isomerization, which can be exploited to control polymer structure and properties with high spatial and temporal precision [285, 286]. Light offers unique advantages over traditional stimuli due to its ability to deliver significant energy locally and instantaneously, enabling polymerization, depolymerization, and functionalization reactions under mild conditions ([287, 288]. These properties have been harnessed for applications ranging from smart materials and actuators to biomedical devices and intracellular polymerization, where light-triggered reactions can be used to modulate cellular functions or deliver therapeutics  [289, 290]. As the understanding of photochemical mechanisms and the interplay between light and polymer matrices advances, light-secretive polymers are poised to play a significant role in future adaptive and multifunctional material systems  [291, 292].

Light-responsive polymers undergo structural or property changes upon exposure to light of specific wavelengths. These polymers typically contain photochromic groups such as azobenzene, spiropyran, diarylethene, or coumarin derivatives [293-296].

Azobenzene-containing polymers undergo trans-cis isomerization upon UV irradiation, leading to significant changes in molecular geometry and physical properties [297] (Fig. 13). This photoisomerization is reversible, with thermal or visible light exposure inducing cis-trans back-isomerization. Spiropyran-based polymers exhibit reversible ring-opening/closing reactions upon UV/visible light exposure, accompanied by dramatic changes in polarity and color [124, 298-300].

 

 

Figure 13   : Azobenzene-containing polymers undergo trans-cis isomerization upon UV irradiation

 

Recent developments in light-responsive polymers have focused on shifting the activation wavelength to the near-infrared (NIR) region, which offers deeper tissue penetration and reduced phototoxicity for biomedical applications [301]. Additionally, two-photon activated systems have been developed to achieve higher spatial resolution in applications such as photolithography and 3D printing [302].

The integration of light-responsive elements with other stimuli-responsive components has led to the development of multi-responsive systems with enhanced functionality and versatility [303].

 

 

2.3.1. Scientific Principles

Photochemical Mechanisms

 

The fundamental principle underlying light-responsive polymers involves the absorption of photons by chromophores, leading to electronic excitation and subsequent molecular transformations [295]. These transformations can include:

 

i.       Photoisomerization: The most common mechanism, exemplified by azobenzene's trans-cis isomerization upon UV irradiation. The energy barrier for this process is typically overcome by photon absorption, causing a change in molecular geometry that affects the polymer's macroscopic properties [304].

ii.       Photocleavage: Certain bonds, such as o-nitrobenzyl esters, undergo irreversible cleavage upon UV exposure, enabling controlled degradation or release of encapsulated molecules [305].

iii.       Photocrosslinking: Groups like coumarins and cinnamates undergo [2+2] cycloaddition reactions under UV light, creating crosslinks between polymer chains [306].

iv.       Photoredox reactions: Involving electron transfer processes that can trigger polymerization, degradation, or functionalization reactions [307].

 

Energy Transfer and Quantum Efficiency

The efficiency of photochemical processes in polymers depends on several factors Eq.12:

 

        (12)

 

Where  represents the quantum yield. Factors affecting quantum efficiency include chromophore concentration, polymer matrix effects, and competing deactivation pathways [308].

 

2.3.2. Categorization of Light-Responsive Polymers

Based on Response Type

i. Reversible Systems: Azobenzene-containing polymers [309]   - Spiropyran-based materials [310], & Diarylethene-functionalized polymers (Irie et al., 2014)

ii. Irreversible Systems: o-Nitrobenzyl-containing polymers [311], & Phenacyl ester-based materials [312]

Based on Structural Changes

 i.Shape-changing polymers: Materials that undergo macroscopic deformation upon light, exposure [313]

         ii. Sol-gel transitioning systems**: Polymers that switch between solution and gel states, [314]

iii. Surface-modifying polymers**: Materials with light-controllable surface properties (Luo & Shoichet, 2004)

Based on Activation Wavelength

i. UV-responsive(200-400 nm)

ii. Visible-light responsive(400-700 nm)

iii. NIR-responsive(700-1000 nm) (Rwei et al., 2015)

 

2.3.3. Mechanisms

 

Azobenzene Photoisomerization

The trans-cis isomerization of azobenzene represents one of the most studied photochemical processes Fig 5. This process involves a change in the N=N bond configuration, resulting in a significant geometric change from a planar trans form (distance between para carbons ~9.0 Å) to a bent cis form (distance ~5.5 Å) [315]  .

 

Spiropyran Ring-Opening

Spiropyrans undergo a ring-opening reaction to form merocyanine Fig 6. This transformation involves breaking of the C-O bond and results in a change from a colorless, hydrophobic SP form to a colored, zwitterionic MC form [316].

 

2.3.4. Photocrosslinking Mechanisms

 

20

 

---