Transition Metal-Catalyzed Step-Growth Radical Polymerization

Metal-catalyzed atom transfer radical addition (Kharasch reaction) is a highly efficient carbon-carbon bond forming radical reaction. Nowadays, the chemistry is widely applied to chain-growth radical polymerization reactions referred as metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP). In this study, we report a new class of transition metal-catalyzed radical polyaddition proceeding via step-growth polymerization mechanism of a designed monomer, which has a reactive carbon-halogen bond and an unconjugated carbon-carbon double bond in the same molecule. The reaction proceeded by simultaneous chain- and step-growth polymerization, both of which were based on the formation of the growing radical species from a stable carbon-halogen covalent bond. Unprecedented sequence-regulated copolymers with perfect vinyl monomer sequences were also obtained by the step-growth radical polymerization of designed monomers prepared from common vinyl monomers. This strategy will open a new era in the study for designing novel functional synthetic polymers.