Direct observation of cobalt-carbon bond formation in thé catalytic chain transfer polymerization of methyl acrylate using matrix-assisted laser desorption lonization time-of-flight mass spectrometry

A preliminary study into the mechanism of catalytic chain transfer polymerization of methyl acrylate with BF2-bridged cobaloxime is reported. The reaction kinetics indicate two distinct phases of the reaction: an induction time followed by a steady-state polymerization. In the polymerization phase chain transfer occurs. Low molecular weight polymer chains formed during the induction period were isolated and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI). The MALDI spectra clearly indicated poly(methyl acrylate) chains bound to a single cobaloxime molecule. The poly(methyl acrylate)-Co chains were then further reacted with a-methylstyrene at 60 °C. MALDI analyses of the polymer from the second reaction stage indicated a displacement of cobaloxime from the chain end by an a-methylstyrene unit.