Kinetic investigations of polymerization of methyl methacrylate with zirconocenes

The polymerization of methyl methacrylate (MMA) in toluene with Cp2ZrMe2 (1 ) - Ph3C+B(C6F5)(4)(-) (4) as initiating system was kinetically investigate d. This system can be regarded as a combination of the systems described by Collins and Soga. Only if the ratio of 1/4 was larger than 1, monomer conv ersions of more than 99 % and polymers with number-average molecular weight s higher than 200 000 and polydispersities 1.5 - 1.6 were obtained. From a kinetic analysis of time-conversion curves using the software package Predi ci, it can be deduced that the mechanism is consistent with that proposed b y Collins et al. However, the mechanism has to be extended by incorporating a first-order termination reaction of the active species. Rate coefficient s of all elementary reactions were determined from time-conversion curves. The kinetic investigations were accompanied by ab initio calculations, whic h support the assumed kinetic model.