The role of monomer in the chain transfer reaction in cobaloxime-mediated free-radical polymerization

The role of monomer in catalytic chain transfer polymerization was studied by determination of the chain transfer constants of the tetraphenyl derivat ive of cobaloxime boron fluoride (COPhBF) in methyl methacrylate at 60 degr ees C varying the monomer concentration instead of the COPhBF concentration as is common practice. Toluene and tert-butyl acetate were used as diluent s in these studies and it was found that the chain transfer constants obtai ned in the present studies were not significantly different from those obse rved in conventional experiments. These results suggest the absence of a di rect participation of monomer molecules in the hydrogen abstraction step in catalytic chain transfer.