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-bridge 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 of 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.