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Abstract <p>A series of <i>rac</i>-Et(2-MeInd)<sub>2</sub>ZrMe<sub>2</sub>/octylaluminum aryloxide catalytic systems were prepared, with octylaluminum aryloxides being represented by (2,6-<sup><i>t</i></sup>Bu<sub>2</sub>,4-Me-PhO-)AlOct<sub>2</sub> (Al<sub>1BHT</sub> (Oct)), (2,6-<sup><i>t</i></sup>Bu<sub>2</sub>PhO-)AlOct<sub>2</sub>· (Al<sub>1DTBP</sub> (Oct)), (2,6-<sup><i>t</i></sup>Bu<sub>2</sub>,4-Me-PhO-)<sub>2</sub>AlOct (Al<sub>2-BHT</sub> (Oct)), and (2,6-<sup><i>t</i></sup>Bu<sub>2</sub>PhO-)<sub>2</sub>AlOct (Al<sub>2-DTBP</sub> (Oct)). Octylaluminum aryloxides proved to be effective activators of the zirconocene precatalyst in the homo- and copolymerization of olefins. In order to identify the generality and/or specificity of catalyst activation by octylaluminum aryloxides (Al(Oct)), the catalytic performance of the catalytic systems was compared to that of the previously investigated systems activated with isobutylaluminum aryloxides (Al(IBu)). The activator structure was shown to affect the catalytic activity, molecular weight characteristics, copolymer composition, and thermophysical properties of the polymers produced. When compared to isobutylaluminum aryloxides (other conditions being equal), the catalytic systems with octylaluminum aryloxides exhibited a higher activity in homo- and copolymerization (99– 326 kg<sub>polymer</sub> mol<sub>Zr</sub><sup>–1</sup> bar<sup>–1</sup>) and a higher degree of propylene incorporation into E/P copolymers (up to 26 mol %), but lower molecular weights of the copolymers produced (57–105 kg/mol). The systems activated with isobutylaluminum aryloxides achieved 28–277 kg<sub>polymer</sub> mol<sub>Zr</sub><sup>–1</sup> bar<sup>–1</sup>, up to 15 mol %, and 92–265 kg/mol, respectively. At the same time, the copolymers produced using Al(Oct) activators had low melting points (91<i>–</i>112°C) and low degrees of crystallinity (9–28%), even in ternary copolymers (terpolymers) with low comonomer content. This is indicative of statistical distribution of comonomer units in macromolecular chains, which limits the formation of extended methylene sequences. The study further provides the results of mechanical tests of the copolymers synthesized using the different activator types. The copolymers obtained with octylaluminum aryloxides exhibited somewhat lower levels of tensile stress (σ = 5–16 MPa) and elongation at break (ε = 100–840%) than the samples synthesized over catalytic systems with isobutylaluminum aryloxides (σ = 5–25 MPa; ε = 400–1050%).</p>

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rac-Et(2-MeInd)2ZrMe2/Octylaluminum Aryloxide Catalysts in Homopolymerization and Copolymerization of Ethylene, Propylene, and 5-Ethylidene-2-Norbornene

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  • 发表日期：

    2025年12月18日

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  • E. E. Faingol’d,
  • S. L. Saratovskikh,
  • A. N. Panin,
  • I. V. Zharkov,
  • O. N. Babkina,
  • N. N. Lashmanov,
  • D. S. Vinnikov,
  • N. M. Bravaya

摘要

Abstract

A series of rac-Et(2-MeInd)2ZrMe2/octylaluminum aryloxide catalytic systems were prepared, with octylaluminum aryloxides being represented by (2,6-tBu2,4-Me-PhO-)AlOct2 (Al1BHT (Oct)), (2,6-tBu2PhO-)AlOct2· (Al1DTBP (Oct)), (2,6-tBu2,4-Me-PhO-)2AlOct (Al2-BHT (Oct)), and (2,6-tBu2PhO-)2AlOct (Al2-DTBP (Oct)). Octylaluminum aryloxides proved to be effective activators of the zirconocene precatalyst in the homo- and copolymerization of olefins. In order to identify the generality and/or specificity of catalyst activation by octylaluminum aryloxides (Al(Oct)), the catalytic performance of the catalytic systems was compared to that of the previously investigated systems activated with isobutylaluminum aryloxides (Al(IBu)). The activator structure was shown to affect the catalytic activity, molecular weight characteristics, copolymer composition, and thermophysical properties of the polymers produced. When compared to isobutylaluminum aryloxides (other conditions being equal), the catalytic systems with octylaluminum aryloxides exhibited a higher activity in homo- and copolymerization (99– 326 kgpolymer molZr–1 bar–1) and a higher degree of propylene incorporation into E/P copolymers (up to 26 mol %), but lower molecular weights of the copolymers produced (57–105 kg/mol). The systems activated with isobutylaluminum aryloxides achieved 28–277 kgpolymer molZr–1 bar–1, up to 15 mol %, and 92–265 kg/mol, respectively. At the same time, the copolymers produced using Al(Oct) activators had low melting points (91–112°C) and low degrees of crystallinity (9–28%), even in ternary copolymers (terpolymers) with low comonomer content. This is indicative of statistical distribution of comonomer units in macromolecular chains, which limits the formation of extended methylene sequences. The study further provides the results of mechanical tests of the copolymers synthesized using the different activator types. The copolymers obtained with octylaluminum aryloxides exhibited somewhat lower levels of tensile stress (σ = 5–16 MPa) and elongation at break (ε = 100–840%) than the samples synthesized over catalytic systems with isobutylaluminum aryloxides (σ = 5–25 MPa; ε = 400–1050%).