Polynuclear Catalysis:  Enhancement of Enchainment Cooperativity between Different Single-Site Olefin Polymerization Catalysts by Ion Pairing with a Binuclear Cocatalyst

A new multicenter ethylene polymerization process is described whereby two different single-site catalysts, one competent for producing vinyl-terminated oligomers or macromonomers and one competent for producing high-molecular weight ethylene-α-olefin copolymers, are held in close spatial proximity...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2002-11, Vol.124 (47), p.13966-13967
Main Authors: Abramo, Graham P, Li, Liting, Marks, Tobin J
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Polymerization
Preparation, kinetics, thermodynamics, mechanism and catalysts
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Summary:A new multicenter ethylene polymerization process is described whereby two different single-site catalysts, one competent for producing vinyl-terminated oligomers or macromonomers and one competent for producing high-molecular weight ethylene-α-olefin copolymers, are held in close spatial proximity via ion-pairing with a dianionic binuclear bis-borate cocatalyst. Ethylene polymerizations mediated by stoichiometrically appropriate quantities of Me2Si( t BuN)(η5-3-ethylindenyl)ZrMe2 and Me2Si( t BuN)(η5-C5Me4)TiMe2 activated by the bis-borate cocatalyst [Ph3C+]2[1,4-(C6F5)3BC6F4B(C6F5)3 -2] yield a more homogeneous polyethylene product when compared to control polymerizations using the mononuclear activator [Ph3C+][B(C6F5)4 -]. The bulk and spectroscopic properties of the polymer produced using the binuclear activator are consistent with highly branched polyethylene.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja020870b