CORRELATION BETWEEN CONFIGURATION CONFORMATION OF ZIRCONOCENES ON THE STEREOSELECTIVITY OF THE PROPYLENE POLYMERIZATION REACTION

The catalytic performance (activity and polymer properties) of metallocenes with different symmetries in combination with methylaluminoxane (MAO) in the polymerization of propylene has been investigated at different temperatures, under standardized reaction conditions. The zirconocene rac-ethylene bis(eta(5)-1-indenyl) zirconium (IV) dichloride, with C-2 symmetry, produces isotatic polypropylene and isopropylidene(eta(5)-cyclopentadienyl) (eta(5)-9-fluorenyl) zirconium (IV) dichloride, with C-S symmetry, syndiotactic polypropylene. The degree of the tacticity of these polymers increases with decreasing polymerization temperature. Only atactic polypropylene was formed with the unbridged zirconocenes bis(eta(5) cyclopentadienyl) zirconium (IV) dichloride and bis(eta(5)-indenyl) zirconium (IV) dichloride at any temperature investigated (10-60 degrees C).