Thermo-responsive biodegradable hydrogels have been developed for drug delivery systems and temporary implants. The physically cross-linked, thermo-responsive hydrogels derived from the mixture of two enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA were first reported by Fujiwara and Kimura in 2001.  This PLA-PEG-PLA stereocomplex hydrogel, however, showed relatively low storage modulus (ca. 1,000 Pa) and thus, was insufficient for many applications as injectable implant materials. Modification of molecular weight and micellar structure significantly improved the mechanical strength of these hydrogels. Micelles composed of block copolymers with different PEG block length are shown to possess unique and different properties from the micelles composed of block copolymers with the same PEG block length. These mixed copolymer micelles show a controllable sol-gel transition at wide temperature range between 4 and 80oC. Sol-gel transition at around body temperature is achieved by adjusting the copolymer ratio. The resulting hydrogels exhibit storage modulus significantly higher than those previously reported

Mechanistic studies on micellar structures of PLA-PEG-PLA triblock copolymers towards well controlled stereocomplexed hydrogels

243rd National Meeting (2012)

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