NOVEL POLYPHOSPHAZENE POLY(LACTIDE-CO-GLYCOLIDE) BLENDS - MISCIBILITYAND DEGRADATION STUDIES/

A novel biodegradable polymer blend was developed for potential biomed ical applications. A 50:50 poly(lactide-co-glycolide) (PLAGA) was blen ded in a 50:50 ratio with the followiing polyphosphazenes (PPHOS): pol y[(25% ethyl glycinato)(75% p-methylphenoxy)phosphazene[, poly[(50% et hyl glycinato)(50% p-methylphenoxy)phosphazene], and poly[(75% ethyl g lycinato)(25% p-methylphenoxy)phosphazene] to obtain Blends A, B, and C, respectively, using a mutual solvent technique. The miscibility of these blends was determined by measuring their glass transition temper ature (T-g) using differential scanning calorimetry. After fabrication using a casting technique, the degradation of the matrices was examin ed. Differential scanning calorimetry showed one glass transition temp erature for each blend which was between the T-g's of their respective parent polymers indicating miscibility of the blends. Surface analysi s by scanning electron microscopy showed the matrices to have smooth u niform surfaces. Degradation studies showed near-zero order degradatio n kinetics for the blends with Blends A and B losing 10% of their mass after two weeks and Blend C degrading more rapidly (30% mass loss dur ing the same period). These findings suggest that these novel biodegra dable PLAGA/PPHOS blends may be useful for biomedical purposes. (C) 19 97 Elsevier Science Limited. All rights reserved.