In Vitro Hydrolytic Surface Degradation of Poly(glycolic acid):  Role of the Surface Segregated Amorphous Region in the Induction Period of Bulk Erosion

The in vitro hydrolytic degradation of thin (ca. 100 μm) films of poly(glycolic acid) (PGA) has been studied, focusing on the kinetics of degradation of the near surface phases. The emphasis of this work is to describe the nature of the initial “induction” period of hydrolysis of biodegradable polyesters, where water absorption is initiating into the surface phase and weight loss is not detectable. The kinetics of surface degradation are shown to be related to the enrichment of amorphous PGA in the surface phases. This study presents results from both surface and bulk phase characterization of short-term (