Synthesis of poly(chloroprene)-based block copolymers by RAFT-mediated emulsion polymerization

Abstract

Chloroprene (CP)-based block copolymers were synthesized via the RAFT-mediated emulsion polymerization of CP using polyacrylate macro-chain transfer agents (CTAs) via a one-pot (in-situ), two-step process. The quantitative formation of hydrophobic macro-CTA in the latex in the first step and subsequent incorporation of CP monomer into the latex using a high internal phase emulsion (HIPE) in the second step were observed to be crucial for producing poly(CP)-based block copolymers. The formation of poly(CP)-b-poly(n-butyl acrylate)s were confirmed by an evident shift in the SEC traces and the 1H and DOSY NMR measurements. The block copolymers exhibited microphased structures composed of the poly(CP) matrix with low Tg (−30 °C) and the poly(nBA) spherical phase with lower Tg (−50 to −60 °C), as revealed by dynamic mechanical analysis (DMA) and transmission electron microscopy (TEM). This study represents the first report of the controlled synthesis of poly(CP)-based block copolymers by RAFT-mediated emulsion polymerization using HIPE.