ANALYSIS AND CHARACTERIZATION OF RESORBABLE DL-LACTIDE TRIMETHYLENE CARBONATE COPOLYESTERS

Randomized copolyesters of DL-lactide (DLLA) and trimethylene carbonate (TMC) in a wide range of composition were synthesized, analysed and characterized with the aim of assessing their potential benefit in biomedical applications. The chemical composition was analysed using H-1-nuclear magnetic resonance (NMR) spectroscopy. Sequence information was obtained by means of C-13-NMR spectroscopy. From the occurrence of TMC-lactate-TMC triads it is concluded that synthesis by melt copolymerization at 190-degrees-C is accompanied by transesterification. The copolymers were characterized by means of differential scanning calorimetry (DSC), tensile testing and accelerated hydrolysis tests at 80-degrees-C. Their properties were compared with those of the parent polymers. It was found that all properties under investigation are strongly affected by the molar composition: with increasing TMC moieties the glass transition temperature (T(g)) is depressed, the tensile strength reduced, the elasticity increased and the in vitro hydrolysis rate decelerated.