Bimodal and Highly Branched Polyethylenes Using Dual-Site Nickel Catalysts Supported on an Unsymmetrical BIAN-PI Compartmental Ligand Scaffold

Zhang, Qiuyue; Lin, Wenhua; Ning, Zhao; Wang, Yizhou; Ma, Yanping; Solan, Gregory A.; Liang, Tongling; Sun, Wen-Hua

doi:10.1021/acs.macromol.3c02601

Macromolecules

2024

DOI: 10.1021/acs.macromol.3c02601

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Bimodal and Highly Branched Polyethylenes Using Dual-Site Nickel Catalysts Supported on an Unsymmetrical BIAN-PI Compartmental Ligand Scaffold

Qiuyue Zhang,

Wenhua Lin,

Zhao Ning

et al.

Abstract: A straightforward two-step synthesis of a new family of electronically distinct para-biphenylene-linked 1,2-bis(iminois disclosed. Their reaction with two equivalents of NiBr 2 (DME) results in occupation of the two inequivalent N,N′ pockets within the BIAN-PI framework to afford the binuclear nickel(II) bromide complexes, [2′-CMeN{1-[2,6-(Ph 2 CH) 2 -4-R-C 6 H 2 N]-2-[3,3′,5,5′-i Pr 4 -1,1′-(C 6 H 2 ) 2 -4-N]-

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Cited by 4 publications

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Amino‐containing α‐Diimine Nickel Complexes with Adjustable Electronic Properties and their Effective Use in Forming Highly Branched Polyethylene

Zhang,

Wang,

Wang

et al. 2024

Macro Chemistry & Physics

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A family of ten amino‐containing bis(arylimino)acenaphthene‐nickel (II) bromide complexes varied in the electronic properties of para‐substituents (R = Me, iPr, tBu, OMe, Cl, F, NO2) as well as two amino‐free comparators (R = Me, Cl) are synthesized in good yield from their corresponding unsymmetrical N,N’‐ligands. All organic compounds are well characterized by different analysis techniques. On activation with Me2AlCl, all nickel complexes exhibit moderate to high activities with a maximum activity up to 14.19 × 106 g (PE) mol−1 (Ni) h−1 and deliver narrow dispersed polyethylene (PDI: 1.85–2.65) with adjustable molecular weight values (Mw: 5.27–18.49 × 105 g mol−1). The presence of remote fluoro‐ group and (4‐amino‐3,5‐dimethylphenyl)(phenyl)methyl group has their own unique influence on activity due to their different electronic and steric properties. Nevertheless, the latter with higher steric hindrance results in better thermal stability of the current catalytic system. Moreover, all polyethylene is highly branched and exhibits typical characteristics of thermoplastic elastomers, especially good mechanical properties (εb up to 1175%) and elastic recovery rate (up to 86%).

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Amino‐containing α‐Diimine Nickel Complexes with Adjustable Electronic Properties and their Effective Use in Forming Highly Branched Polyethylene

Zhang,

Wang,

Wang

et al. 2024

Macro Chemistry & Physics

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Synthesis of chain‐end functionalized highly branched polyethylene waxes using sterically open α‐diimine Ni(II) catalysts

Chen,

Lu,

Dai

2024

Journal of Polymer Science

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Our previous research showed that bis(benzocyclopentyl) α‐diimine Pd(II) complexes can facilitate chain transfer and polar monomer insertion in ethylene (co)polymerization. In this study, we synthesized two bis(benzocyclopentyl) α‐diimine Ni(II) complexes with different backbones. The Ni(II) complexes exhibited high activities (0.63–7.23 × 106 g·mol−1 h−1) and produced low molecular weight (2.7–7.8 kg mol−1) polyethylene waxes with high branching densities (43–86/1000 C) in ethylene polymerization. The use of a catalyst with a butyl backbone resulted in polyethylene waxes with significantly higher molecular weights. The axial substituent restriction strategy employed in the nickel catalyst allows for a sterically open structure, reducing the molecular weight of the resulting polyethylene by over two orders of magnitude, compared to ethyl catalysts without axial restrictions. This enables the production of polyethylene wax grade products with improved properties. The branched polyethylene wax chain ends were found to be aryl‐functionalized according to NMR characterization analysis, while the double bonds were absent. Also, the choice of solvent affects the branching, molecular weight, and chain end composition of the polyethylene wax.

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Geometrically Constrained Cofacial Bi-Titanium Olefin Polymerization Catalysts: Tuning and Enhancing Comonomer Incorporation Density

Bao,

Li,

Chan

et al. 2024

ACS Catal.

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A series of shape-persistent bis-[C(sp 3 )-chelating] Ti 2 (plus Zr 2 and Hf 2 ) complexes with a rigid linker component (xanthene or dibenzofuran) are presented. These structurally diverse assemblies display limited yet different conformational flexibility, and crucially, such geometric constraints confer access to a range of intermetallic separations and orientations to potentially enhance catalytic activity and cooperative effects. For ethylene polymerizations, the Ti 2 catalysts (in conjunction with trityl borate) exhibit greater efficiencies and produced polymers with higher M w than mononuclear controls, which is significant considering the more crowded environment for cofacial bimetallic sites. Proficient 1-hexene incorporations were observed for ethylene-(α-olefin) copolymerization reactions. The F-substituted maryl/dibenzofuran-linked catalyst (5), which is revealed by NMR analysis to be conformationally dissimilar to its F-absent congener, produced copolymers with higher M w and elevated 1-hexene incorporation levels (up to 44%), when compared with its mono-Ti control (19%). These results suggest that catalyst frameworks with suitably adjustable conformations and Ti•••Ti distances can facilitate bimetallic enchainment interactions with α-olefin substrates and their insertion.

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Bimodal and Highly Branched Polyethylenes Using Dual-Site Nickel Catalysts Supported on an Unsymmetrical BIAN-PI Compartmental Ligand Scaffold

Cited by 4 publications

References 71 publications

Amino‐containing α‐Diimine Nickel Complexes with Adjustable Electronic Properties and their Effective Use in Forming Highly Branched Polyethylene

Amino‐containing α‐Diimine Nickel Complexes with Adjustable Electronic Properties and their Effective Use in Forming Highly Branched Polyethylene

Synthesis of chain‐end functionalized highly branched polyethylene waxes using sterically open α‐diimine Ni(II) catalysts

Geometrically Constrained Cofacial Bi-Titanium Olefin Polymerization Catalysts: Tuning and Enhancing Comonomer Incorporation Density

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