The grafting of acrylamide onto poly(epsilon-caprolactone) and poly(1,5-dioxepan-2-one) using electron beam preirradiation. II. An in vitro degradation study on grafted poly(epsilon-caprolactone)

Acrylamide was graft polymerized onto the surface of a biodegradable semicr ystalline polyester, poly(epsilon-caprolactone). Electron beam irradiation at a dose of 5 Mrad was used to generate initiating species in the polyeste r. The degradation in vitro at pH 7.4 and 37 degrees C in a phosphate buffe r solution was studied for untreated, irradiated and acrylamide-grafted pol ymers. In the case of poly(epsilon-caprolactone), all materials showed simi lar behavior in terms of weight loss. No significant decrease in weight was observed up to 40 weeks, after which the loss of weight accelerated. The m ain differences in degradation behavior were found for the average molecula r weights, (M) over bar(n), and M,. Virgin poly(epsilon-caprolactone) maint ained M, and M, up to about 40 weeks, whereas the irradiated and grafted po ly(epsilon-caprolactone) showed similar continuous declines in (M) over bar (n) and (M) over bar(w) throughout the degradation period. (C) 1999 John Wi ley & Sons, Inc.