Synthesis of stimuli-responsive polymers by living polymerization:: Poly(N-isopropylacrylamide) and poly(vinyl ether)s

Precision synthesis via living polymerization has created new possibilities to a variety of stimuli-responsive polymers. This review highlighted the synthesis of poly(N-isopropylacrylamide) [poly(NIPAM)] and poly(vinyl ether)s by living polymerization. Poly(NIPAM) is a well-known thermoresponsive polymer, and the related well-defined polymers including block copolymers and end-functionalized polymers have been synthesized intensively throughout the world since the discovery of its living radical polymerization. This recent revolutionary change in the investigations on poly(NIPAM) is first described. Poly(vinyl ether)s can be stimuli-responsive with high sensitivity when having certain functional groups. A variety of stimuli-responsive polymers with controlled sequences and/or shapes such as block, gradient copolymers, and star-shaped polymers were designed and synthesized by living cationic polymerization in the presence of an added base. The self-assembling behavior of the obtained polymers is also demonstrated. In addition to the selective synthesis of stimuli-responsive polymers, the recent development of initiating systems for the vinyl ether living polymerization by our group is briefly reviewed.