Ethylene/propylene copolymerization over three conventional C2-symmetric metallocene catalysts: Correlation between catalyst configuration and copolymer microstructure

Authors

  • Li Lu,

    1. CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
    2. Graduate School, Chinese Academy of Sciences, Beijing 100049, China
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  • Hui Niu,

    1. CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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  • Jin-Yong Dong,

    Corresponding author
    1. CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
    • CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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  • Xutao Zhao,

    1. Petrochemical Research Institute, PetroChina Company Ltd, Beijing 100190, China
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  • Xuteng Hu

    1. Petrochemical Research Institute, PetroChina Company Ltd, Beijing 100190, China
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Abstract

This work reports on a correlation between catalyst configuration and copolymer microstructure for ethylene/propylene (E/P) copolymerization using three conventional C2-symmetric metallocene catalysts, namely, rac-Et(Ind)2ZrCl2 (EBI), rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (SiPh), and rac-CH2(3-tBu-Ind)2ZrCl2 (MBu), with MAO as a common cocatalyst. Copolymerization reactions were conducted in toluene at three different temperatures with varied E/P ratios. Some typically obtained copolymers were characterized in detail using 13C-NMR spectroscopy, by which triad distribution data were elaborated in a statistical method to determine the reactivity ratios (rE and rP) of the comonomers, which were also obtained by Fineman-Rose estimation. The production of alternating-like copolymers from EBI is attributed to the rapid interconversion between two conformation states of the active site, one of which favors the incorporation of propylene but the other one does not. Both SiPh and MBu are structurally more rigid and of larger dihedral angles than EBI; however, SiPh which owns open active site conformation tend to produce random copolymers at all studied temperatures, and for MBu, sterically hindered catalyst, block-like copolymers were obtained. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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