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Ethylene-Propene Copolymerization with C1-symmetric ansa-Fluorenyl-zirconocene Catalysts: Effects of Catalyst Structure and Comonomer on Molar Mass

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Abstract

Ethylene-propene copolymers have been synthesized by three C1-symmetric metallocene molecules (1, 2, and 3), having tert-butyl substituents on the Cp moiety, on the fluorenyl moiety, or on both moieties, and methylaluminoxane (MAO) at different polymerization temperatures and monomer concentrations. Copolymers were investigated by 13C-NMR, 1H-NMR, and SEC analyses. A relationship was found between [EEE]/[E] ratios and copolymer molar masses in each series: the higher the [EEE]/[E] ratio, the lower the copolymer molar mass. At parity of [EEE]/[E] ratio, copolymer molar mass follows the order 1 >> 3 > 2. Chain end group analysis reveals that copolymers mainly terminate when propene is the last inserted unit, confirming that it is the greater facility of Mt-P-E-poly(E-co-P) to terminate that influences the copolymer molar mass. Among the catalysts considered, catalyst 1, which gives syndiospecific polypropene, gives greater activities, comonomer incorporation, and molar masses. Catalyst 3, which gives isospecific polypropene, in copolymerization performs better than 2, having the same bridge, with respect to activities, ethylene content, and molar masses. The good performance of this catalyst arises from the not necessity of polymer chain to back skip when ethylene is the last inserted unit.

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Acknowledgments

This work was financially supported by Total. We thank G. Zannoni and D. Piovani (ISMAC) for their valuable cooperation in NMR and SEC analysis.

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Authors and Affiliations

  1. CNR — Istituto di Scienze e Tecnologie Chimiche “G. Natta” (CNR-SCITEC), via Alfonso Corti 12, 20133, Milano, Italy

    Simona Losio, Laura Boggioni, Massimiliano Cornelio & Incoronata Tritto

  2. Total Petrochemicals Research, Zone Industrielle C, B-7181, Feluy, Belgium

    Abbas Razavi

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  1. Simona Losio
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  2. Laura Boggioni
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  3. Massimiliano Cornelio
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  4. Abbas Razavi
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  5. Incoronata Tritto
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Correspondence to Incoronata Tritto.

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Losio, S., Boggioni, L., Cornelio, M. et al. Ethylene-Propene Copolymerization with C1-symmetric ansa-Fluorenyl-zirconocene Catalysts: Effects of Catalyst Structure and Comonomer on Molar Mass. Chin J Polym Sci 38, 220–230 (2020). https://doi.org/10.1007/s10118-020-2348-3

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