Macromonomer Chain Growth in the Radical Polymerization of MMA by Cobalt(II) Catalyzed Chain Transfer

Properties of the radical polymerization of methyl methacrylate in the presence of cobalt(II) tetraphenylporphyrin ((TPP)Co^II•) as a chain transfer catalyst are reported. Reversible addition of (L)Co‐H to macromonomers gives living character to the oligomer olefins that grow to higher molecular weight without altering the primary polymer structural features. Incorporation of reversible termination of oligomer radicals in the mechanistic model for chain transfer catalysis by (L)Co^II• complexes is an essential feature of the catalytic chain transfer process.

Average degree of polymerization as a function of monomer conversion for the (TPP)Co^II• mediated CCT polymerization of MMA in C₆D₆ initiated by AIBN at different concentrations of (TPP)Co^II•.