Sequential synthesis of well-defined poly(vinyl acetate)-block-polystyrene and poly(vinyl alcohol)-block-polystyrene copolymers using difunctional chloroamide-xanthate iniferter

Abstract

The sequential synthesis of well-defined poly(vinyl acetate)-block-polystyrene copolymer (PVAc-b-PS) and poly(vinyl alcohol)-block-polystyrene copolymer (PVA-b-PS) is challenging due to inactive vinyl acetate monomer and active styrene monomer. In this study, sequential polymerizations of vinyl acetate and styrene monomer were carried out by reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP) using an innovative amide based difunctional chloroamide-xanthate iniferter [S-(1-((3-(2-chloropropanamido)propyl) amino)-1-oxopropan-2-yl) O-ethyl xanthate]. Synthesized difunctional iniferter was very stable under basic condition and allowed the sequential reactions without chain-end modification and purification steps. Synthesized iniferter was first used for xanthate-mediated RAFT polymerization of VAc, followed by ATRP of styrene to achieve controlled molecular weight of PVAc-b-PS with lower polydispersity (≤1.3). Then, PVAc-b-PS was successfully converted to the corresponding PVA-b-PS by hydrolysis. Synthesized block copolymers were characterized by size exclusion chromatography, nuclear magnetic resonance spectroscopy, transmission electron microscopy, and dynamic light scattering.