Novel initiating systems for the living polymerization of acrylates and methacrylates

Abstract

AbstractThe polymerization of methyl methacrylate with lithiated initiators in the presence of aluminium alkyls in toluene has living character but it deviates from conventional first‐order kinetics and the polymers have fairly broad molecular weight distributions. This results from the formation and precipitation of a coordinative polymer network in which the lithium ions of the living chain ends are coordinated to the in‐chain ester carbonyl groups. Thus, the network formation can be prevented by adding Lewis bases like methyl pivalate which coordinate to the living chain ends instead of the polymer. Alternatively, one can introduce tetraalkylammonium salts aiming at an exchange of the lithium ion by a less electropositive cation. Both approaches lead to linear first‐order time conversion plots for the polymerization of methacrylates and acrylates and to narrow molecular weight distributions, i.e., to a living and controlled polymerization. With these new initiating systems, various block and graft copolymers can be synthesized.