COPOLYMERS OF 1,5-DIOXEPAN-2-ONE AND L-DILACTIDE OR D,L-DILACTIDE - IN-VIVO DEGRADATION BEHAVIOR

Copolymers of 1,5-dioxepan-2-one (DXO) and L- or D,L-dilactide have be en synthesized and characterized. The molar ratio of the two monomers was around 20/80 of DXO and L- or D,L-lactide respectively. In vivo st udies on rats revealed significant differences in tissue response betw een the semicrystalline DXO/L-LA copolymer and the amorphous DXO/D,L-L A copolymer. The materials were characterized pre- and post-implantati on by size-exclusion chromatography (SEC), differential scanning calor imetry (DSC), nuclear magnetic resonance (NMR), and light-microscopy. Degradation seems to follow an autocatalytic hydrolysis mechanism. The amorphous copolymer was degraded at a faster rate and gave a less pro nounced foreign body reaction as compared to the semicrystalline one.