Investigation of the microstructure of polypropylene prepared with ansa and fluxional metallocene catalysts with an extended Coleman-Fox model

Abstract

Temperature (T) effects on the microstructure of polypropylene made with metallocene catalysts have been investigated with the theoretical framework originally developed by Coleman and Fox and extended to the stereospecific polymerization of propylene with two-state ansa and fluxional metallocene catalysts. T effects on the polymer microstructure are mainly due to factors other than changes in the intrinsic stereoselectivity of the two states. The model has been applied to the stereosequence distributions of polypropylene prepared with the C 1-symmetric Me 2Si(Ind)(Flu)ZrCl 2 complex, activated with methyl aluminoxane, over a range of T and monomer concentration ([M]) values. The use of these two variables, in combination with the Coleman-Fox model (or a kinetic model), allows more reliable estimates of fundamental parameters, especially when the microstructure is a weak function of one of these variables at a constant value of T (e.g., [M]). © 2005 Wiley Periodicals, Inc.