A General Strategy To Access Alternating Styrene/Substituted Styrene Copolymers by Using a Traceless Controlling Group

We herein report a synthetic strategy for alternating copolymers of styrene and substituted styrenes by utilizing alpha-styryl boronate pinacol ester (StBpin) as the co-monomer through radical alternating copolymerization followed by protodeboronation. The excellent alternating polymerization behavior of the StBpin co-monomer in such a radical polymerization system is considered to be attributed to the steric hindrance and radical stabilization exerted by the Bpin group. This strategy is effective with a wide range of substituted styrene co-monomers regardless of the electronic nature of the substituents, and the protodeboronation of the alternating Bpin-containing polymers is highly efficient without polymer backbone alternation. RAFT living polymerization was also compatible with this approach. Thus, this strategy provides a way to build-up alternating copolymers consisting of similar styrene-type co-monomers, which has been inaccessible by conventional synthetic methods. A radical alternating copolymerization has been realized between alpha-styryl boronate pinacol ester and diverse styrene co-monomers. Facile removal of the traceless boronyl controlling group further provides a unified access to a wide range of alternating polystyrenes that are non-trivial to obtain through conventional approaches.image