Synthesis, Thermosensitive Gelation and Degradation Study of a Biodegradable Triblock Copolymer

A series of biodegradable triblock copolymers PLA-PEG-PLA were synthesized by ring-opening polymerization of D,L-lactide using PEG as initiator. The structures and molecular weights of the triblock copolymers were characterized by1H-NMR and GPC.Their thermal properties were tested by DSC. The thermosensitive gelation behaviors and hydrolytic degradation were investigated. Sol-gel transition was observed with proper LA/EG ratios from 2.23 to 2.57. Besides, the sol-gel transition temperature has a close relation with the concentration and molecular weight of the triblock copolymers. The hydrolytic degradation experiment indicates the copolymers with lower LA/EG ratios degrade faster, and the degradation probably occurred at the PLA block at random.