Influence of metallocene structures on ethene copolymerization with 1-butene and 1-octene

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 1998-02, Vol.128 (1), p.215-227
• Main Authors: Suhm, J, Schneider, M.J, Mülhaupt, R
• Format: Article
• Language: English
• Subjects: Ethene/1-butene copolymers; Ethene/1-octene copolymers; Metallocene; Ziegler–Natta catalysis
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(97)00175-1

Ethene/1-octene and ethene/1-butene copolymerization using various methylaluminoxane-activated metallocene catalysts, e.g. silylene-bridged substituted bisindenyl zirconocene systems and halfsandwich titanocene, was performed at 40°C in toluene. The influence of the ligand substitution on comonomer incorporation, catalyst activity, molar mass, molar mass distribution, degree of polymerization and copolymerization parameters was investigated in ethene/1-octene copolymerization at constant comonomer ratio and in ethene/1-butene copolymerization as a function of varying ethene/1-butene feed mass ratios. In ethene/1-octene copolymerization the highest comonomer incorporation was achieved with MAO-activated Me 2Si(Me 4Cp)( N- tert-butyl)TiCl 2 catalyst. Best performance in terms of comonomer incorporation combined with high catalyst activity and molar mass was found for silylene-bridged bisindenylzirconocenes, where 2-methyl substitution promoted high degree of polymerization and benzannelation accounted for improved catalyst activity, comonomer incorporation and randomness of comonomer incorporation. In ethene/1-butene copolymerization at high 1-butene feed content silylene-bridged substituted bisindenyl systems showed polymerization characteristics similar to that of ethene/1-octene copolymerization. The influence of 2-methyl substitution on activity and comonomer incorporation was significant only at low 1-butene feed content. Storage moduli and glass transition temperature of the poly(ethene-co-1-butene) copolymers decreased with increasing 1-butene content.