Cu(0)/2,6-bis(imino)pyridines catalyzed single-electron transfer-living radical polymerization of methyl methacrylate initiated with poly(vinylidene fluoride-co-chlorotrifluoroethylene)

A series of 2,6-bis(imino)pyridines, as common ligands for late transition metal catalyst in ethylene coordination polymerization, were successfully employed in single-electron transfer-living radical polymerization (SET-LRP) of methyl methacrylate (MMA) by using poly(vinylidene fluoride-co- chlorotrifluoroethylene) (P(VDF-co-CTFE)) as macroinitiator with low concentration of copper catalyst under relative mild-reaction conditions. Well-controlled polymerization features were observed under varied reaction conditions including reaction temperature, catalyst concentration, as well as monomer amount in feed. The typical side reactions including the chain-transfer reaction and dehydrochlorination reaction happened on P(VDF-co-CTFE) in atom-transfer radical polymerization process were avoided in current system. The relationship between the catalytic activity and the chemical structure of 2,6-bis(imino)pyridine ligands was investigated by comparing both the electrochemical properties of Cu(II)/2,6-bis(imino)pyridine and the kinetic results of SET-LRP of MMA catalyzed with different ligands. The substitute groups onto N-binding sites with proper steric bulk and electron donating are desirable for both high-propagation reaction rate and C-Cl bonds activation capability on P(VDF-co-CTFE). The catalytic activity of Cu(0)/2,6-bis(imino) pyridines is comparable with Cu(0)/2,2′-bipyridine under the consistent reaction conditions.