Polymerization of ethene initiated with a mixture of siloxane‐bridged mono‐ and dinuclear zirconocenes

Abstract

Abstract In the polymerization of ethene cocatalyzed with modified methylaluminoxane, the catalyst activities of the siloxane‐bridged dinuclear zirconocenes, tetramethyldisiloxanediylbis(cyclopentadienylindenylzirconium dichloride) ( 3 ) and hexamethyltrisiloxanediylbis(cyclopentadienylindenylzirconium dichloride) ( 4 ) were lower than that obtained with the siloxane‐bridged mononuclear zirconocene, tetramethyldisiloxanediyldicyclopentadienyldimethylzirconium ( 1 ). On the other hand, weight‐average molecular weight M̄ w and ratio of weight‐ to number‐average molecular weights M̄ w /M̄ n of polyethene (PE) obtained with 3 or 4 were higher than those of PE obtained with 1. For a binary mixture of 1/3 or 1/4 , it was found that the obtained PE exhibits a bimodal molecular weight distribution for an appropriate composition of the mixed zirconocenes. M̄ w /M̄ n of PE could be adjusted by changing the relative concentrations of the two zirconocenes.