Synthesis and properties of temperature-responsive chitosan by controlled free radical polymerization with chitosan-RAFT agent.

The temperature-responsive chitosan was synthesized by free radical polymerization of N-isopropylacrylamide (NIPAM) at 60 degrees C in the presence of RAFT-chitosan agent. The chitosan was subsequently modified with phthalic anhydride and with S-1-dodecyl-S'-(alpha,alpha'-dimethyl-alpha''-acetic acid) trithiocarbonate to serve as reversible addition fragmentation chain transfer (RAFT) agent. The polymerization results show that the graft polymerization proceeded via RAFT process, while the "well-defined" graft polymers were successfully synthesized. The temperature played an important role on the self-assembly in H2O dispersion and the morphologies of chitosan-g-PNIPAMs. To our knowledge, this is the first thermosensitive chitosan prepared from controlled graft modification of chitosan by RAFT polymerization.