Heterogenized "ligand-Free" lanthanide catalysts for the homo- and copolymerization of ethylene and 1,3-butadiene

Woodman, Timothy J., Sarazin, Yann, Fink, Gerhard, Hauschild, Klaus and Bochmann, Manfred (2005) Heterogenized "ligand-Free" lanthanide catalysts for the homo- and copolymerization of ethylene and 1,3-butadiene. Macromolecules, 38 (8). pp. 3060-3067. ISSN 0024-9297

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Abstract

Silica-supported lanthanide catalysts have been prepared from the reaction of dehydroxylated silica and tris(bistrimethylsilyl)amido lanthanides Ln[N(SiMe3)(2)](3) (Ln = Sc, Y, La, Nd, Sm, Gd, Dy). On activation with (AlBu3)-Bu-i (TIBA), the compounds catalyze the polymerization of ethylene, with the scandium catalyst showing the highest activity. There is an inverse relationship between ionic radius of the lanthanide metal and the activity of the resulting catalyst. The polymer produced was highly linear and of high molecular weight. Activation with magnesium alkyls was less effective but gave polyethylene of slightly higher molecular weight. The supported lanthanides, when activated with TIBA, were also active for the polymerization of 1,3-butadiene, with very high molecular weight polymers being produced. In all cases the polymer was found to be predominately 1,4-cis (typically 85-90% by diad analysis), with only scandium producing a much higher level of 1,4-trans units. The system was also shown to copolymerize ethylene and butadiene, with large differences in the polymeric products depending on the both the choice of the lanthanide and the feed ratio of the monomer. With both neodymium and dysprosium multiblock polymers consisting of 1,4-cis, 1,4-trans, and ethylene blocks were obtained. With scandium two distinct modes of polymerization were detected, with both multiblock 1,4-cis and a somewhat alternating ethylene/1,4-trans block structure observed in the C-13 NMR spectra.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 16 Jun 2011 13:58
Last Modified: 21 Apr 2020 20:11
URI: https://ueaeprints.uea.ac.uk/id/eprint/32758
DOI: 10.1021/ma047454r

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