Trifluoromethoxy- and Fluorobenzhydryl-Tuned Nickel Catalysts for Polyethylene Elastomers

Trifluoromethoxy- and Fluorobenzhydryl-Tuned Nickel Catalysts for Polyethylene Elastomers

A series of <i>para</i>-trifluoromethoxy-substituted and fluorobenzhydryl-functionalized 1,2-bis(imine)acenaphthene ligands: 1-[2,6-{(4-F-C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>CH}<sub>2</sub>-4-F<sub>3</sub>COC<sub>6</...

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Bibliographic Details
Main Authors: Ming Liu, Min Sun, Yanping Ma, Yizhou Wang, Mingfeng Li, Wen-Hua Sun
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Molecules
Subjects:
nickel catalysts
dual steric-electronic tuning
highly branched polyethylenes
high-temperature polymerization
thermoplastic elastomers (TPEs)
Online Access:https://www.mdpi.com/1420-3049/30/13/2706
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Summary:A series of <i>para</i>-trifluoromethoxy-substituted and fluorobenzhydryl-functionalized 1,2-bis(imine)acenaphthene ligands: 1-[2,6-{(4-F-C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>CH}<sub>2</sub>-4-F<sub>3</sub>COC<sub>6</sub>H<sub>2</sub>N]-2-(ArN)C<sub>2</sub>C<sub>10</sub>H<sub>6</sub> (Ar = 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub> <b>L1</b>, 2,6-Et<sub>2</sub>C<sub>6</sub>H<sub>3</sub> <b>L2</b>, 2,6-iPr<sub>2</sub>C<sub>6</sub>H<sub>3</sub> <b>L3</b>, 2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub> <b>L4</b>, 2,6-Et<sub>2</sub>-4-MeC<sub>6</sub>H<sub>2</sub> <b>L5</b>), were synthesized and used to generate their corresponding nickel(II) bromide complexes (<b>Ni1</b>–<b>Ni5</b>). Elemental analysis, <sup>19</sup>F NMR, and FT-IR spectroscopy were employed to characterize these five nickel complexes. Single-crystal X-ray diffraction of <b>Ni2</b> and <b>Ni4</b> confirmed distorted tetrahedral geometries. Upon activation with either EtAlCl<sub>2</sub> (ethylaluminum dichloride) or EASC (ethyl aluminum sesquichloride), these complexes showed exceptional high activities (up to 22.0 × 10<sup>6</sup> g PE mol<sup>−1</sup> (Ni) h<sup>−1</sup>) and remarkable thermal stability (4.82 × 10<sup>6</sup> g PE mol<sup>−1</sup>(Ni) h<sup>−1</sup> at 80 °C) towards ethylene polymerization. The resulting polyethylenes are highly branched, with the type and extent of branches tunable by temperature, solvent, and co-catalyst choice. Moreover, these polymers demonstrated excellent tensile strength (<i>σ<sub>b</sub></i> up to 20.7 MPa) and elastic recovery (up to 58%), characteristic of thermoplastic elastomers (TPEs). These results highlight the dual role of trifluoromethoxy and fluorobenzhydryl groups in enhancing catalytic performance and polymer properties.
ISSN:1420-3049

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