Block Copolymer Hydrogels

Abstract

Block copolymer hydrogels are three‐dimensional polymeric networks that can absorb a considerable amount of water to maintain their semisolid morphology. Chemically cross‐linked hydrogels which can be prepared through disulfide bond formation, photopolymerization, or click chemistry, exhibit a nonreversible phase transition state. In contrast, physically cross‐linked hydrogels can be formed via self‐assembly of amphiphilic block copolymers, in response to environmental stimuli, including pH and/or temperature, and show a sol‐gel phase transition. Importantly, these stimuli‐sensitive physical hydrogels can exist as a sol state prior to administration, and subsequently translate to a gel state after administration under the human body condition. Consequently, the stimuli‐sensitive hydrogels have attracted significant interest for their potential applications in the site‐specific pharmaceutical (drug/protein) delivery and tissue regeneration. The article focuses on synthesis, properties, and biomedical applications of stimuli‐responsive block copolymer hydrogels that exhibit a reversible sol‐gel phase transition in response to temperature, pH, pH/temperature, and other stimulus conditions.