Thermal and photo-RAFT polymerization of 2,2,2-trifluoroethyl α-fluoroacrylate

Abstract

The RAFT polymerization of 2,2,2-trifluoroethyl α-fluoroacrylate (FATRIFE) was investigated under thermal conditions and light irradiation. The performances of 4 different chain transfer agents (3,5-dimethyl-1H-pyrazole-1-carbodithioate (CTA₁), 4-cyano-4-(2-phenylethanesulfanylthiocarbonyl)sulfanylpentanoic acid (CTA₂), dibenzyl trithiocarbonate (CTA₃), and ethyl 2-(phenylcarbonothioylthio) propionate (CTA₄)) were compared under thermal conditions. CTA₂ afforded relatively good control of the polymerization with relatively low dispersities (apparent molar mass M_n,SEC ∼ 37.8 kg mol⁻¹vs. PMMA, Đ < 1.10). Pseudo-first-order polymerization kinetics and a linear increase of the molar masses versus monomer conversions were observed. The RAFT polymerization of FATRIFE was further explored under photoirradiation using CTA₂ as the chain transfer agent and white LED lamps (14 W × 2). In the absence of exogenous radical sources or catalysts, controlled polymerization was observed at room temperature. A linear increase of molar masses (up to 25.3 kg mol⁻¹) with monomer conversions and low dispersities (Đ < 1.10) were successfully obtained. Temporal control of the polymerization was also observed using light ON/OFF experiments. Poly(FATRIFE) based macroCTA synthesized by photoRAFT was also extended with 1,1,1,3,3,3-hexafluoropropan-2-yl 2-fluoroacrylate and tert-butyl-2-trifluoromethacrylate/FATRIFE.