Copolymerization of Ethylene and 1-Octene by Syndiospecific Metallocenes: Comparison of Me2C(Cp)(Flu)ZrMe2 with Et(Cp)(Flu)ZrMe2

Abstract

Copolymerizations of ethylene with 1-octene have been carried out by using two kinds of metallocene: highly syndiospecific isopropylidene(1-η^5-cyclopentadienyl)(1-η^5-fluorenyl)dimethylzirconium (Me₂C(Flu)(Cp)ZrMe₂,1) and less syndiospecific (1-fluorenyl-2-cyclopentadienylethane)dimethyl-zirconium (Et(Flu)(Cp)ZrMe₂, 2), in the presence of [Ph₃C][B(C_6F_5)₄] as a cocatalyst. The ethano bridged 2 compound of smaller dihedral angle showed much higher activity than the isopropyl bridged 1 compound in the ethylene homo- and co-polymerizations. The catalytic activities of the two catalysts were enhanced about twice in the presence of a suitable amount of 1-octene in the feed. The two catalysts showed a noticeable difference in the comonomer reactivity. The compound 1 is characterized by lower r_E, taken as an index of ethylene reactivity, and higher reactivity of 1-octene than the compound 2.