Copolymerization of 2,2-Dimethyltrimethylene Carbonate and l,l-Lactide

Abstract

The ring-opening polymerization of mixtures of 2,2-dimethyltrimethylene carbonate (DTC) and l,l-lactide (LLA) in the melt, with diethyl zinc or dibutyltin dimethoxide as initiator, results in the formation of random copolymers. LLA polymerizes first in a fast reaction, followed by a slow polymerization of DTC. Investigations of the polymerization mechanism reveal that DTC is randomly inserted into LLA-LLA diads. The microstructure of the copolymers was determined by triad analysis of the 13C NMR spectra. The thermal behavior of the copolymers, especially the dependence of the glass transition temperature on the copolymer composition, was studied, and a deviation from the behavior predicted by the Fox equation was observed.