Synthesis and Crystallization of Poly(vinyl acetate)-g-Poly(l-lactide) Graft Copolymer with Controllable Graft Density

Abstract

Graft copolymers of poly(vinyl acetate)-graft-poly(l-lactide) (PVAc-g-PLLA) comprising biodegradable graft chains were synthesized through the ring-opening polymerization of lactide. The partially hydrolyzed PVAcs, that is, poly(vinyl acetate-co-alcohol) [P(VAc-co-VA)], having degrees of hydrolysis of 5.2 and 9.6% were used as the macromolecular multifunctional initiator. The chemical structure and crystallization behavior of PVAc-g-PLLA were investigated. Graft length and density in PVAc-g-PLLA can be controlled by varying the lactide/P(VAc-co-VA) feed ratio and the degree of hydrolysis of P(VAc-co-VA). Graft length of PLLA chain and molecular weight of graft copolymer increased with the lactide/P(VAc-co-VA) feed ratio. The graft length and density of PVAc-g-PLLA had a significant effect on its crystallization behavior. The crystallization and spherulitic growth of PVAc-g-PLLA were decelerated with decreasing the length of PLLA graft chain or increasing the graft density, due to the branching effects and...