Propene polymerization with zirconocene catalysts supported on siloxane copolymers

A supported version of zirconocene catalysts on siloxane copolymers having 1,2,3,4-tetramethylcyclopentadienyl (Cp'')-fluorenyl (Flu) (I) or cyclopentadienyl (Cp)-fluorenyl (II) groups as substituents was prepared and applied to propene polymerization using methylalumoxane (MAO) or [Ph3C][B(C6F5)(4)] as cocatalyst. Catalyst (I), which was soluble in toluene, exhibited very low activity, whereas catalyst (II), which was composed of a toluene soluble (Cat-A) and an insoluble fraction (Cat-B), displayed a fairly high activity. Both catalysts (A and B) give a mixture of syndiotactic, atactic and a small quantity of isotactic polypropene, with a fraction of syndiotactic pentads ranging from about 50-75%. In contrast, the corresponding non-supported catalyst gives almost completely atactic polypropene.