Syntheses of 2-(trifluoromethyl)acrylate-containing block copolymers via RAFT polymerization using a universal chain transfer agent†
This article describes the synthesis and characterization of a series of well-defined block copolymers (BCPs) comprising a poly(vinyl acetate-alt-tert-butyl-2-trifluoromethacrylate) (poly(VAc-alt-MAF-TBE)) alternating copolymer segment and a homopolymer segment (PVAc, polystyrene, poly(meth)acrylate, polyacrylamide, or poly(N-vinylpyrrolidone)) using RAFT polymerization under mild conditions (at 40 °C). The abilities of four chain transfer agents (CTAs) to copolymerize VAc and MAF-TBE were compared. Recently reported as a universal RAFT CTA, cyanomethyl 3,5-dimethyl-1H-pyrazole-1-carbodithioate (CDPCD) afforded better-defined BCPs compared to O-ethyl-S-(1-methoxycarbonyl)ethyldithiocarbonate (CTA-XA), 2-cyano-2-propyl benzodithioate (CPDB), and 4-cyano-4-(2-phenylethanesulfanylthiocarbonyl)sulfanyl pentanoic acid (PETTC). While the chain extension of poly(VAc-alt-MAF-TBE)-DPCD with vinyl acetate (VAc), styrene (St), n-butyl acrylate (nBA), and dimethyl acrylamide (DMA) led to well-defined poly(VAc-alt-MAF-TBE)-b-poly(M) BCPs with acceptable dispersity values (Đ ≤ 1.36), high Đ values were observed when methyl methacrylate (MMA) and N-vinylpyrrolidone (NVP) were used to form the second block. An attempt to synthesize poly(M)-b-poly(VAc-alt-MAF-TBE) block copolymers using poly(M)-DPCD as the macroCTA led to copolymers with high Đ values (1.53–2.0).