RAFT/MADIX copolymerization of vinyl acetate and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO).

Radical ring-opening polymerization of cyclic ketene acetals (CKA) can lead to the formation of polyesters [1]. Copolymerization of CKAs with vinylic monomers is indeed a powerful tool to get degradable polymers. The aim of this work is to obtain a well defined degradable poly(vinyl acetate) by RAFT copolymerization of a CKA, namely 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), and vinyl acetate (VAc), using methyl (ethoxycarbonothioyl)sulfanyl acetate (MEA), as controlling agent (Scheme 1). Scheme 1. Synthesis of P(VAc-co-BMDO) via RAFT copolymerization of VAc and BMDO mediated by MEA Different copolymers were prepared by changing the molar composition of the starting monomer mixture (from 5 to 30 mol% of BMDO). The conversion of monomers was evaluated by NMR spectroscopy. In all the cases, the evolution of molar masses and the dispersity values (lower than 1.26) versus conversion confirmed the controlled feature of the copolymerizations. The livingness of the obtained chains was further evaluated by chain extension experiments and their degradability shown after treatment with KOH/MeOH.