Reversible addition–fragmentation chain transfer synthesis and micellar characteristics of biocompatible amphiphilic poly(vinyl acetate)-graft-poly(N-vinyl-2-pyrrolidone) copolymers

Poly(vinyl acetate)-graft-poly(N-vinyl-2-pyrrolidone) (PVAc-graft-PNVP) copolymers of low grafting density and with a constant PVAc backbone of DPn = 72, were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. A poly(vinyl acetate-co-vinyl chloroacetate) P(VAc-co-VClAc) gradient copolymer, also prepared by RAFT, was used as a macromolecular chain transfer agent. For this purpose it was functionalized by substitution of chlorine groups by xanthate moieties. In the NVP “grafting-from” polymerization step, PVAc-graft-PNVP copolymers were obtained, with PNVP contents from 85 to 95 mol% and with, on the average, 2–3 grafts per backbone with DPn ranging from 196 to 530. Their self-aggregation in aqueous medium revealed the formation of star-like micelles, with, at 25 °C, a partially “frozen-in” PVAc core and a PNVP corona.