Kinetics of Group Transfer Polymerization

Abstract

The group transfer polymerization (GTP) of methyl methacrylate (MMA) and tert.-butyl methacrylate (TBMA), catalyzed by bifluoride, is of first order with respect to monomer and catalyst concentrations. A slightly negative order with respect to initiator concentration is observed, indicating an inhibitive function of the initiator. Termination reactions occur at lower catalyst concentrations. They are very pronounced for TBMA and result in incomplete conversions. For MMA, at lower catalyst and higher initiator concentrations, induction periods are observed which increase when lowering the temperature. This is related with the formation of active chains. The Arrhenius plots for the propagation rate constants of MMA and TBMA are very similar to those found in the anionic polymerization using bulky counterions. Based on the kinetic results and on the microstructure of the polymers, a mechanism for the addition of monomer is proposed.