Stopped-flow polymerizations of ethene and propene in the presence of the catalyst system rac-Me2Si(2-methyl-4-phenyl-1-indenyl)2ZrCl2/methylaluminoxane

The kinetics of ethene and propene polymn. at 20-60° in the presence of the homogeneous catalyst system rac-Me2Si(2-methyl-4-phenyl-1-indenyl)2ZrCl2/methylaluminoxane was investigated by means of stopped-flow techniques. The specific rate of chain propagation, measured at the very short reaction times typical of this method, turned out to be ≈102 times higher for ethene than for propene; this suggests that diffusion limitations through the poly(ethylene) pptg. at longer reaction times may be responsible for the fact that the two monomers polymerize instead at comparable rates under "std." conditions. The concn. of active sites is significantly lower than the anal. Zr concn.