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Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

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Abstract

A collection of ten related 1,2-bis(imino)acenaphthene-nickel(II) halide complexes, [1-[2,6-{(C6H5)2CH}2-4-{C(CH3)3}-C6H2N]-2-(ArN)C2C10H6]NiX2 (X = Br: Ar = 2,6-Me2C6H3 Ni1, 2,6-Et2C6H3 Ni2, 2,6-iPr2C6H3 Ni3, 2,4,6-Me3C6H2 Ni4, 2,6-Et2-4-MeC6H2 Ni5) and (X = Cl: Ar = 2,6-Me2C6H3 Ni6, 2,6-Et2C6H3 Ni7, 2,6-iPr2C6H3 Ni8, 2,4,6-Me3C6H2 Ni9, 2,6-Et2-4-MeC6H2 Ni10), each bearing one sterically and electronically enhanced N-2,6-dibenzhydryl-4-t-butylphenyl group, have been prepared and fully characterized. The unsymmetrical nature of the chelating bis(imino)acenaphthene is confirmed in the paramagnetic 1H NMR spectra for Ni1–Ni10, while the molecular structures of Ni1, Ni2 and Ni6 highlight the unequal steric protection of the nickel center imposed by their respective N,N-ligands. On activation with either Et2AlCl or MMAO, all the nickel complexes were highly active catalysts in ethylene polymerization [as high as 1.26 × 107 g of PE per mol of Ni per h] affording exceptionally high molecular weight (up to 3.1 × 106 g mol−1) hyper-branched polyethylene. Analysis of the mechanical properties reveals the ultra-high molecular weight polymers possess high tensile strength, excellent shape fixity and elastic recovery (up to 69%) as well as high elongation at break (εb = 843.9%); such materials offer a promising alternative to current thermoplastic elastomers (TPEs).

Graphical abstract: Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

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Publication details

The article was received on 18 Sep 2017, accepted on 28 Sep 2017 and first published on 29 Sep 2017


Article type: Paper
DOI: 10.1039/C7PY01606A
Citation: Polym. Chem., 2017, Advance Article
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    Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

    Q. Mahmood, Y. Zeng, E. Yue, G. A. Solan, T. Liang and W. Sun, Polym. Chem., 2017, Advance Article , DOI: 10.1039/C7PY01606A

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