The grafting of acrylamide onto poly(epsilon-caprolactone) and poly(1,5-dioxepan-2-one) using electron beam preirradiation. III. The grafting and in vitro degradation of chemically crosslinked poly(1,5-dioxepan-2-one)

Acrylamide was graft polymerized onto the surface of a chemically crosslink ed and amorphous biodegradable polyester, poly(1,5-dioxepan-2-one). Electro n beam irradiation at a dose of 5 Mrad was used to generate the initiating species in the polyester. The degradation behavior in vitro at pH 7.4 and 3 7 degrees C in a phosphate buffer solution was studied for untreated, irrad iated, and acrylamide-grafted polymer. Differences in weight loss performan ce were observed between virgin and treated polymers. The acrylamide-grafte d poly(1,5-dioxepan-2-one) was totally degraded after 43 weeks as compared to 48 weeks for the irradiated and 55 weeks for the virgin polymer. On the other hand, the treated polymers showed a higher resistance to degradation in terms of weight loss during the intermediate part of the degradation, i. e., between about 5 and 35 weeks. After this period, the irradiated and par ticularly the acrylamide grafted poly(1,5-dioxepan-2-one) degraded much mor e rapidly than the virgin polymer. (C) 1999 John Wiley & Sons, Inc.