Nitrone-Mediated Radical Coupling of Polymers Derived from Reverse Iodine-Transfer Polymerization

The current study describes the synthesis of iodine-end-capped polystyrene (PS) and poly(methyl methacrylate) (PMMA) precursors using reverse iodine-transfer polymerization, which, in a second step, are used in nitrone-mediated radical coupling (NMRC) reactions. Initially, the reverse iodine polymerization of both monomers is studied and optimized in order to obtain iodine-end-capped materials with controlled molecular weights and low dispersities. Subsequently, NMRC of both PS and PMMA precursors is carried out in the presence of CuCl as a halide-exchange agent. Coupling efficiencies of x(c) = 0.754 for PS-I and 0.84 for PMMA-I are observed; however, the addition of 10 equivalents of styrene is required to promote the coupling in the case of methacrylate. The presence of the desired alkoxyamine functionality in mid-chain position of the products is evidenced via quenching experiments.