Composition, Morphology and Properties of Poly(lactic acid) and Poly(butylene succinate) Copolymer System via Coupling Reaction

The poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) copolymer systems with different reactive time were synthesized for the first time via the homo-/cross-coupling reaction of PLA and PBS. Nuclear magnetic resonance spectroscopy (1H-NMR) results showed that the homo-coupling of PLA occurred much earlier than the cross-coupling of PLA with PBS. Also, the compositions of PLA and PBS copolymer systems contained homo-coupled PLA (h-PLA) but not homo-coupled PBS, cross-coupled PLA-b-PBS copolymer (mainly PLA terminated with hydroxyl group and PBS terminated with carboxyl group, up to 24 h), PLA and PBS. There was little difference of the molecular weight between all the PLA and PBS copolymer systems and PLA/PBS blends demonstrated by size exclusion chromatography (SEC) results, which indicated that the morphologies of the samples might have greater effect on the final properties than the molecular weight. Scanning electron microscope (SEM) results showed that the morphologies of PLA and PBS copolyme...