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

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