Synthesis and characterization of thermosensitive hydrogels with both supramolecular and hyperbranched structures

Abstract

Abstract New novel kinds of thermosensitive hydrogels with supramolecular structures were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAM) and polypseudo rotaxanes in the presence of N,N- methylenebisacylamide (BIS) as a cross-linker. The polypseudorotaxanes were prepared by supramolecular self-assemblies of α- cyclodextrins threaded onto (4A-PEG) polymers. The structure of the hydrogels were characterized in detail with FTIR techniques. The analytical results demonstrated that a channel-type crystalline structure of inclusion complexes (ICs) remains in as-obtained hydrogels. Their swelling behavior was measured gravimetrically in the temperature range from 20 to 60 °C. The supramolecular structured hydrogels by RAFT polymerization (RAFT gels) showed accelerated shrinking kinetics to conventional hydrogel (CG), surprisingly.