Copolymerization of Ethylene and Cyclopentene with Zirconocene Catalysts: Effect of Ligand Structure of Zirconocenes

Copolymerization of ethylene and cyclopentene (CPE) was carried out with various non-bridged and bridged zirconocene catalysts using methylaluminoxane as a cocatalyst. Non-bridged metallocene catalysts effected ethylene homopolymerization without copolymerization. On the other hand, bridged zirconocene catalysts produced copolymers containing cis-1,2-cyclopentane units. Among the used catalysts, rac-ethylenebis(indenyl)zirconium dichloride [Et(Ind)2ZrCl2] gave copolymers containing the highest amount of CPE units by 1,2-insertion or 1,3-insertion. Temperature-rising elution fractionation of the copolymers using 1,2-dichlorobenzene as a solvent showed a broad distribution of copolymer composition in copolymers obtained by specific zirconocene catalysts.