Morpholine-based RAFT agents for the reversible deactivation radical polymerization of vinyl acetate and N-vinylimidazole

Abstract

Reversible addition�fragmentation chain transfer (RAFT) polymerization of less-activated monomers in a controlled fashion is challenging due to the high reactivity and instability of the propagating radicals. We have designed dithiocarbamate-based RAFT agents with morpholine as activating �Z� group and benzyl, ethyl(1-ethanoate)yl, ethyl(2-propanoate)yl and cyanomethyl as �R� leaving groups and investigated them for the reversible deactivation radical polymerization of vinyl acetate (VAc) and N-vinylimidazole (N-VIm). RAFT polymerization of VAc and N-VIm at 70 �C using azobisisobutyronitrile as a free radical initiator proceeded in a controlled fashion as demonstrated by a linear increase in molar mass with conversion. Interestingly, the polymerization of VAc followed fast kinetics (approx. 60 min) with good to moderate control affording high-molar-mass poly(VAc) polymers. Furthermore, the synthesized chain transfer agents were able to polymerize N-VIm under controlled conditions. The morpholine RAFT agents bearing cyanomethyl and ethyl(2-propanoate)yl leaving groups showed better control of the polymerization of VAc and N-VIm compared to the others. � 2020 Society of Chemical Industry. � 2020 Society of Chemical Industry