PNNL

Abstract

The aqueous solutions of poly(ethylene glycol)grafted with poly(lactic acid-co-glycolic acid) flow freely at room temperature but form gels at higher temperature. The existence of micelles in water at low plymer concentration was confirmed by Cro-transmission electron microscopy and dye solubilization studies. The micellar diameter and critical micelle concentration are about 9 nm and 0.47 wt. % respectively. The critical gel concentation, above which a gel phase appears was 16 wt. % and sol-to-gel transition temperature was slightly affected by the concentration in the range of 16~25 wt.%. At sokl-to-gel transition, viscosity increased abruptly and C-NMR showed molecular motion of hydrophilic poly(lactic acid-co-glycolic acid) side-chains increased. The hydrogel of PEG-g-PLGA with hydrophilic backbones was transparent during degradation and remained a gel for one week, suggesting a promising material for short-term drug delivery.