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

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journal contribution
posted on 08.08.2018, 14:09 by Qaiser Mahmood, Yanning Zeng, Erlin Yue, Gregory A. Solan, Tongling Liang, Wen-Hua Sun
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-Me2C6H3Ni1, 2,6-Et2C6H3Ni2, 2,6-iPr2C6H3Ni3, 2,4,6-Me3C6H2Ni4, 2,6-Et2-4-MeC6H2Ni5) and (X = Cl: Ar = 2,6-Me2C6H3Ni6, 2,6-Et2C6H3Ni7, 2,6-iPr2C6H3Ni8, 2,4,6-Me3C6H2Ni9, 2,6-Et2-4-MeC6H2Ni10), 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).


This work was supported by the National Natural Science Foundation of China (no. 21374123 and U1362204) and the National Key Research and Development Program of China (2016YFB1100800). QM is grateful to the CAS-TWAS president’s fellowship. GAS thanks the Chinese Academy of Sciences for a Visiting Fellowship.



Polymer Chemistry, 2017, 8 (41), pp. 6416-6430 (15)

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry


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Polymer Chemistry


Royal Society of Chemistry





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Electronic supplementary information (ESI) available: X-ray crystallographic data. CCDC 1553630 (Ni1), 1553631 (Ni2), 1553632 (Ni6). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7py01606a;The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.