A new form of controlled growth free radical polymerization

Abstract A new form of controlled growth free radical polymerization leading to narrow polydispersity polymers and/or block copolymers is described. The process is based on the polymerization of monomers in the presence of macromonomers of general structure CH 2 =C(Z)CH 2 (A) n [(A) n = radical leaving group, Z = activating group] and displays many of the characteristics of living polymerizations. The process is most suited to methacrylic monomers but with the appropriate choice of reaction conditions (high temperatures and/or low conversions) it can also be applied to acrylic and styrenic monomers. The macromonomers are conveniently prepared by catalytic chain transfer to alkyl cobalt(III) complexes or by addition‐fragmentation chain transfer. The factors which determine the efficiency of cobalt complexes for molecular weight reduction in free radical emulsion and solution polymerization of methyl methacrylate are also discussed.