Homo- and copolymerization of ethylene and α-olefins over 1- and 2-siloxy-substituted ethylenebis(indenyl)zirconium and ethylenebis(tetrahydroindenyl)zirconium dichlorides

P Lehmus, E Kokko, O Harkki, Reko Leino, Luttikhedde HJG, JH Nasman, JV Seppala

    Tutkimustuotos: LehtiartikkeliArtikkeliTieteellinenvertaisarvioitu

    62 Sitaatiot (Scopus)

    Abstrakti

    The influence of siloxy substitution of ethylene-bridged bis(indenyl)- and bis(tetrahydro-indenyl)zirconium dichlorides on ethylene/alpha-olefin copolymerization and ethylene homopolymerization performance was investigated. Ethylene was copolymerized with 1-hexene and 1-hexadecene over rac-[ethylenebis(1-(tert-butyldimethylsiloxy)-3-indenyl)]zirconium dichloride (1), rac-[ethylenebis(1-(tert-butyldimethylsiloxy)-4,5,6,7-tetrahydro-3-indenyl)]zirconium dichloride (H1), rac-[ethylenebis(2-(tert-butyldimethylsiloxy)-1-indenyl)] zirconium dichloride (2), and rac-ethylenebis(1-indenyl)zirconium dichloride (EBI) using methylaluminoxane (MAO) as cocatalyst. 1-Siloxy substitution was found to remarkably improve the copolymerization ability and 2-siloxy substitution to enhance the polymerization activity of ethylenebis(indenyl)zirconium dichlorides. Optimum homo- and copolymerization performance was observed at a very low Al(MAO) concentration, which for 2 could be reduced to a level of 0.2 mmol/dm(3) by using a small amount of triisobutylaluminum. The 1-siloxy-substituted metallocene catalysts 1 and H1 (hydrogenated 1) revealed decreasing comonomer incorporation and increasing induction times with increasing Al(MAO) concentration, which indicates the presence of unfavorable interactions between these metallocenes and MAO. Chain termination occurred mainly by chain transfer to the monomer and beta-hydrogen transfer to the metal for catalysts with indenyl and tetrahydroindenyl ligands, respectively.
    AlkuperäiskieliEi tiedossa
    Sivut3547–3552
    Sivumäärä6
    JulkaisuMacromolecules
    Vuosikerta32
    Numero11
    TilaJulkaistu - 1999
    OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

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