Biodegradable and thermoreversible hydrogels of poly(ethylene glycol)-poly(ε-caprolactone-co-glycolide)-poly(ethylene glycol) aqueous solutions

The aqueous solutions of triblock copolymers of poly(ethylene glycol)–poly(ϵ‐caprolactone‐co‐glycolide)–poly(ethylene glycol) [PEG–P(CL‐GA)–PEG] undergoing sol–gel transition as the temperature increases from 20 to 60°C were successfully prepared. The thermogelling block copolymers were synthesized by subtle control of the hydrophilic/hydrophobic balance and the chain microstructures. The amphiphilic block copolymer formed micelles in aqueous solution, and the micelle aggregated as the temperature increased. The sol–gel transition of the copolymer aqueous solutions was studied focusing on the structure–property relationship. GA was incorporated into the polymer chain to prevent crystallization of PCL component and increase the polymer degradation. It is expected to be a promising long‐term delivery system for pH‐sensitive drugs, proteins, and genes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008