Mechanism of anionic polymerization of methyl methacrylate in the presence of aluminium alkyls

Abstract

AbstractA bimetallic aluminate complex (‘ate’ complex) is regarded to be the active species in the anionic polymerization of MMA in the presence of aluminium alkyls in toluene. The aluminate end group is supposed to be able to coordinate to the penultimate end group of the polymer chain. As a result, the rate of polymerization is significantly slower than for aluminium‐free polymerization. Excess aluminium alkyl (Al/Li > 1) coordinates to the ester carbonyl groups of monomer and polymer, but there is no evidence for an activated monomer mechanism. To a small extent, the polymerization at −78°C is accompanied by side reactions (e.g. formation of vinyl ketones) but nevertheless it has a certain living character.