In this paper, we report a new metal-free initiating system for living cationic polymerization that proceeds not via the metal-catalyzed activation but via a reversible activation by a carbocation, in which mainly a covalent C-S bond is activated via reversible addition-fragmentation chain transfer (RAFT) mechanism similar to the well-known RAFT radical polymerization (Scheme 1). The cationic polymerization of isobutyl vinyl ether (IBVE) was carried out in the presence of various thioesters employing a trace amount of trifluoromethanesulfonic acid (TfOH) as the cationogen ([TfOH]0 = 10 ppm) . The Mn of the obtained polymers increased in direct proportion to the monomer conversion with relatively narrow molecular weight distributions and agreed well with the calculated values assuming that one transfer agent generated one polymer chain. In addition, the obtained living polymers with C-S terminal were accessible to novel sequenced block copolymers consisting of cationically and radically polymerized segments via the transformation from cationic into radical RAFT polymerization. 

Metal-free living cationic polymerization via reversible addition-fragmentation chain transfer (RAFT) mechanism

246th National Meeting (2013)

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