Synthesis and Polymerization of a Cyclic Macromonomer Based on a Cyclic Polyacrylic Acid

A novel cyclic macromonomer based on a cyclic polyacrylic acid was prepared. Its radical copolymerization with N-isopropylacrylamide (NIPAAm) was carried out to obtain mechanically cross-linked poly(N-isopropylacrylamode) (PNIPAAm) with movable cross-linking points. The swelling ratio of the gel was found to be dependent on pH, indicating that the mobility of the cyclic polyacrylic acid on the polymer chain is responsible for swelling.