Renewable chain transfer agents for metallocene polymerizations: The effects of chiral monoterpenes on the polyolefin molecular weight and isotacticity |
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Authors: | Robert T. Mathers Krishnan Damodaran |
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Affiliation: | 1. Department of Chemistry, Pennsylvania State University, New Kensington, Pennsylvania 15068Department of Chemistry, Pennsylvania State University, New Kensington, Pennsylvania 15068;2. Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 |
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Abstract: | Monoterpenes were used as renewable chain transfer agents and polymerization solvents for metallocene/methylaluminoxane (MAO) catalysis. The polymerization of 1‐hexene, ethylene, and propylene in d‐limonene, hydrogenated d‐limonene and α‐pinene is reported. As detected by 1H NMR analysis of the alkene region, chain transfer to d‐limonene yielded a higher percentage of trisubstituted alkenes. Size exclusion chromatography detected a decrease in molecular weight values resulting from chain transfer to d‐limonene. The [mmmm] pentads for isotactic polypropylene were characterized by 13C NMR and FTIR spectroscopy. Propylene polymerizations with the Et(Ind)2ZrCl2/MAO and Me2Si(Ind)2ZrCl2/MAO catalyst systems in d‐limonene gave [mmmm] pentad values as high as 0.97. For the Et(Ind)2ZrCl2/MAO catalyst system at 0 °C, the mol fraction of [mmmm] pentads increased from 0.86 to 0.94 upon switching the solvent from toluene to d‐limonene. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3150–3165, 2007 |
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Keywords: | chain transfer d‐limonene isotactic metallocene catalysts monoterpenes polyolefins renewable resources |
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