Microstructure–property relationship of l-lactide/trimethylene carbonate/glycolide terpolymers as cardiovascular stent material

Abstract

A series of terpolymers with various compositions were synthesized by ring-opening polymerization of l-lactide (LLA), trimethylene carbonate (TMC) and glycolide (GA), using stannous (II) octoate as initiator. The microstructure–property relationship of the terpolymers was investigated with the aim of evaluating their potential as cardiovascular stent material. The chain microstructure of the PLLA–TMC–GA terpolymers was examined by means of both 1H and 13C nuclear magnetic resonance (NMR) analysis, in comparison with corresponding PLLA–TMC copolymers. The results show that the incorporation of GA moiety instead of TMC moiety leads to shorter average LLA block length. Differential scanning calorimetry (DSC) results show a close relationship between the crystallization behavior and the microstructural sequence. The crystallinity of PLLA-based copolymers mainly depends on the average LLA block length. The mechanical and thermal degradation properties are also affected by both the composition and the chain microstructure, which is of major importance for the development of bioresorbable cardiovascular stent.