Synthesis and characterization of a new thermosensitive chitosan-PEG diblock copolymer

A novel thermosensitive hydrogel was synthesized by block copolymerization of monomethoxy poly(ethylene glycol) macromere (PEG) onto chitosan backbone, using potassium per sulfate as a free radical initiator. This block copolymer exhibits a thermoreversible transition from an injectable solution at low temperature to a gel at body temperature. Synthesized copolymers were characterized using FT-IR, H-1 NMR, C-13 NMR, and DSC techniques. Solubility test was performed to compare water and organo-solubility of chitosan before and after copolymerization. Sol-gel transition behavior was investigated using the via inversion method and viscosity measurements. The gelation behavior makes the chitosan-PEG block copolymers more promising and attractive materials for biomedical applications. (c) 2008 Elsevier Ltd. All rights reserved.