Synthesis and characterization of statistical copolymers of trimethylene carbonate and l-lactide using Mg(II)/Ti(IV) mixed alkoxides as initiator system

Abstract

Copolymers of trimethylene carbonate and l-lactide with distinct compositions were prepared in bulk employing a novel initiator comprising two biocompatible metals. The NMR analyses showed that the initiator, Catylen® S200, has preference for l-lactide incorporation during the copolymerization, which is attested by the deviations in copolymer compositions compared to the monomers feed ratios and differences between the calculated and the observed average block lengths of lactide units. Nevertheless, the presence of higher contents of trimethylene carbonate led to a higher degree of transesterification, furnishing a copolymer with composition close to a true statistical copolymer when the content of carbonate trimethylene is 51wt%. The effects of the composition in the thermal properties and the crystallinity of the copolymers were also investigated by DSC and WAXD respectively.