High-performance polyethylene elastomers using a hybrid steric approach in α-diimine nickel precatalysts

Polymer Chemistry, Journal Year: 2024, Volume and Issue: 15(14), P. 1437 - 1452

Published: Jan. 1, 2024

In this study, hybrid steric hindrance was introduced into the α-diimine structure to prepare a set of nickel complexes, aiming enhance catalytic performance and polyethylene properties simultaneously for ethylene polymerization.

Language: Английский

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Ethylene Polymerizations Catalyzed by Fluorinated “Sandwich” Diimine-Nickel and Palladium Complexes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(22), P. 15143 - 15154

Published: May 23, 2024

Nickel and palladium complexes bearing "sandwich" diimine ligands with perfluorinated aryl caps have been synthesized, characterized, explored in ethylene polymerization reactions. The X-ray crystallographic analysis of the precatalysts 16 6b shows differences from their nonfluorinated analogues 17 19, centered precisely over nickel centers, which results higher buried volumes metal centers relative to analogues. sandwich diimine-palladium 5a 5b containing polymerize a controlled fashion activities that are substantially increased compared Migratory insertion rates relevant methyl agree exhibited bulk experiments. DFT studies suggest facility rotation its preferred orientation perpendicular Pd-alkyl bond into parallel in-plane conformation contributes activity for 18a. For these systems, polymer molecular weights can be via hydrogen addition (hydrogenolysis), is unusual late-transition-metal-catalyzed olefin polymerizations no catalyst deactivation occurring. Sandwich diimine-nickel 6a show about half those classical tetraisopropyl-substituted 2 but again more active than analogous complexes. Ethylene exhibit living behavior, branched ultrahigh-molecular-weight polyethylenes (UHMWPEs) very low-molecular-weight distributions (less 1.1) obtained. activated catalysts stable absence monomer good long-term stability at 25 °C.

Language: Английский

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Preparation of polyethylene elastomers via controlled chain-walking ethylene polymerization for enhanced impact modification of polypropylene

Polymer, Journal Year: 2025, Volume and Issue: unknown, P. 128042 - 128042

Published: Jan. 1, 2025

Language: Английский

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Enhancing Suppression of Chain Transfer via Catalyst Structural Evolution in Ethylene (Co)Polymerization

Chinese Journal of Chemistry, Journal Year: 2023, Volume and Issue: 41(12), P. 1509 - 1516

Published: March 2, 2023

Comprehensive Summary Usually, the aniline‐based late‐transition‐metal catalysts often require bulky steric substituents on both sides of ortho ‐aryl position to achieve efficient suppression chain transfer in ethylene polymerization. In this contribution, we demonstrated that α‐diimine based naphthylamine with only one substituent also excellent capabilities suppress transfer. Firstly, a class nickel and palladium complexes o ‐aryl‐dibenzhydryl or ‐aryl‐dibenzosuberyl were synthesized characterized. Secondly, as‐prepared naphthylamine‐based outstanding activities (up 13.02 × 10 6 g·mol –1 ·h ) yielded lightly branched (16—40/1000C) polyethylenes very high molecular weights (445.8—854.3 kg/mol) comparison, corresponding showed moderate (level 4 —10 5 ), generating moderately (47—78/1000C) (21.6—82.0 kg/mol). Moreover, could copolymerize methyl acrylate (MA), albeit low 3 providing E‐MA copolymers (1.4—16.3 level incorporation ratio (2.4—7.4 mol%) branching density (53—84/1000C). As compared catalysts, displayed superior ability reactions give access (co)polymers orders magnitude higher weight (co)polymerization.

Language: Английский

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Thermostability promotion of α-diimine nickel precatalysts tailored with 2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline for PE elastomer synthesis

New Journal of Chemistry, Journal Year: 2024, Volume and Issue: 48(27), P. 12174 - 12187

Published: Jan. 1, 2024

A set of five nonsymmetrical 1,2-bis(arylimino)acenaphthene–nickel complexes, incorporating 2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline, was designed and prepared to tailor the catalytic attributes for ethylene polymerization.

Language: Английский

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Congestion of steric and electronic factors in α-diimine nickel precatalysts for high-temperature ethylene polymerization in accessing direct PE elastomer

Journal of Molecular Structure, Journal Year: 2024, Volume and Issue: 1316, P. 139037 - 139037

Published: Nov. 1, 2024

Language: Английский

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Development of well-defined olefin block (co)polymers achieved by late transition metal catalysts: Catalyst, synthesis and characterization

Coordination Chemistry Reviews, Journal Year: 2024, Volume and Issue: 522, P. 216195 - 216195

Published: Sept. 18, 2024

Language: Английский

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Unexpected Effect of Catalyst’s Structural Symmetry on the Branching Microstructure of Polyethylene in Late Transition Metal Polymerization Catalysis

ACS Catalysis, Journal Year: 2022, Volume and Issue: 13(1), P. 725 - 734

Published: Dec. 23, 2022

In this study, several α-diimine nickel complexes were prepared by merging a bulky dibenzobarrelene backbone and dibenzhydrylanilines. The single-crystal X-ray diffraction analysis confirmed that the complex Ni1 exists in an anti-conformation, possessing quasi-centrosymmetry. These displayed high activities (above 106 g mol–1·h–1) ethylene polymerization, even at 90 °C, providing polyethylenes with very molecular weights (well above 500 kg/mol). Unexpectedly, slightly branched semi-crystalline (11-34/1000C) melting points obtained these quasi-centrosymmetric catalysts, contrary to those common often render highly polyethylenes. resultant have good mechanical properties, moderate stress break values strain values. Ethylene–methyl undecenoate copolymerization using also gave access high-molecular-weight polar functionalized copolymers. experimental density functional theory calculation results suggested distribution of steric hindrance as-prepared complexes, namely, catalyst's structural symmetry, might be more favorable chain propagation relative branch formation, which was not observed polymerization systems before.

Language: Английский

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Direct synthesis of polyethylene thermoplastic elastomers with high molecular weight and excellent elastic recovery via a hybrid steric bulky strategy

European Polymer Journal, Journal Year: 2023, Volume and Issue: 201, P. 112577 - 112577

Published: Nov. 7, 2023

Language: Английский

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Amide-Functionalized Polyolefins and Facile Post-Transformations

Macromolecules, Journal Year: 2023, Volume and Issue: 56(3), P. 915 - 922

Published: Feb. 2, 2023

Direct copolymerization of olefins with polar monomers to produce functionalized polyolefins has attracted much attention; however, highly efficient incorporation amide functions into is a long-standing challenge because the function pronounced retard chain growth. In this contribution, Vince Lactam's derivatives (VLH, VLMe, and VLBoc) that contain high ring strain an moiety are utilized in ethylene mediated by palladium catalysts. Amide-functionalized polyethylenes, poly(E-VLBoc)s, accessible key characteristics incorporations (up 30.1 mol %), copolymer molecular weights, catalytic activities. The comonomer converts crystalline poly(E-VLBoc)s (Tm = 115–125 °C) noncrystalline transparent (Tg 98–196 °C, optical transmittance (T) 87.6%–90.4%). Both cyclic poly(E-VLBoc) enable facile post-transformations under mild conditions hydrogen bond-containing (-C(O)NH-) poly(E-VLH), difunctionalized (-COOH -NHR) poly(E-VLNHBoc), water-soluble ammonium-functionalized poly(E-VLNH3+). ammonium functionality endows polyolefin antibacterial properties.

Language: Английский

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