Triblock Copolymers of Lactide with Poly(ethylene glycol) and Influence of Stereochemical Composition

摘要

Polymerization of L-lactide (LLA) and poly (ethylene glycol) (PEG) at 120°C using stannous 2-ethyl hexanoate results in ABA triblock copolymers in good yields. The glass transition temperature of the copolymers shows strong dependence on the composition. One- and two-phase triblock copolymers can be prepared by controlling the molecular weight of the PEG soft block, as well as the initial LLA/PEG charge ratio. Incorporation of racemic lactide during polymerization drastically affects the crystallinity of the block copolymers obtained. ~1H and ~(13)C (solid state) NMR are powerful tools for characterization of the polymer materials.