Unprecedented syndioselectivity and syndiotactic polyolefin melting temperature: polypropylene and poly(4-methyl-1-pentene) from a highly active, sterically expanded eta1-fluorenyl-eta1-amido zirconium complex |
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Authors: | Irwin Levi J Miller Stephen A |
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Institution: | Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA. |
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Abstract: | The structurally unique, sterically expanded eta1-fluorenyl-eta1-amido single-site precatalyst, Me2Si(eta1-N-tBu)(eta1-C29H36)ZrCl2.OEt2 (3), upon activation with methylaluminoxane (MAO), is remarkably active and constitutes the most syndioselective alpha-olefin polymerization catalyst system yet reported. 3/MAO affords as-prepared syndiotactic polypropylene with rrrr] > 99% and unprecedented melting temperatures for the unannealed (165 degrees C) and annealed (174 degrees C) polymers. The activity of this system is 4 times that of the prototypical syndioselective catalyst Me2C(eta5-C5H4)(eta5-C13H8)ZrCl2/MAO. The high activity and syndioselectivity of 3/MAO can be extended to the production of syndiotactic poly(4-methyl-1-pentene) with a record melting temperature of 215 degrees C and rrrr] = 97%. |
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