STIMULI-RESPONSIVE POLYMERS: DESIGN PRINCIPLES, POLYMER ARCHITECTURES, AND CONTROLLED FUNCTIONAL RESPONSES

Abstract

Smart polymers undergo reversible physicochemical changes in response to stimuli such as magnetic fields, temperature, pH, light, and external reagents. Advanced polymerization techniques, including reversible addition fragmentation chain transfer (RAFT), atom transfer radical polymerization (ATRP), and ring opening polymerization, enable precise control over polymer architecture and functional group placement, allowing the design of tailored responsive materials. These polymers are widely explored in biomedical applications, drug delivery, biosensing, cosmetics, and soft robotics due to their ability to adapt dynamically to environmental conditions. Poly(N-isopropylacrylamide) is a well-known thermoresponsive polymer extensively studied for drug delivery and sensing. Responsive polymers exist in linear, block, graft, and cross-linked forms, with activation depending on interactions between structural motifs and stimuli. Despite promising results, challenges remain, including immunogenicity, batch variability, synthesis complexity, scalability, and limited understanding of in vivo stimulus accessibility. Covalent adaptable and interpenetrating polymer networks enhance mechanical strength, biocompatibility, and stimuli responsiveness.