Synthesis of highly branched polyethylene using para‐phenyl‐substituted α‐diimine nickel catalysts |
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| Authors: | Fuzhou Wang Ruiping Li Susu Tian Kunbo Lian Dengfeng Guo Weimin Li |
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| Affiliation: | 1. Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, School of Petrochemical Engineering, Changzhou University, Changzhou, China;2. Graduate School of Engineering, Hiroshima University, Higashi‐Hiroshima, Japan |
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| Abstract: | A series of para‐phenyl‐substituted α‐diimine nickel complexes, (2,6‐R2‐4‐PhC6H2N═C(Me))2]NiBr2 (R = iPr ( 1 ); R = Et ( 2 ); R = Me ( 3 ); R = H ( 4 )), were synthesized and characterized. These complexes with systematically varied ligand sterics were used as precatalysts for ethylene polymerization in combination with methylaluminoxane. The results indicated the possibility of catalytic activity, molecular weight and polymer microstructure control through catalyst structures and polymerization temperature. Interestingly, it is possible to tune the catalytic activities ((0.30–2.56) × 106 g (mol Ni·h)?1), polymer molecular weights (Mn = (2.1–28.6) × 104 g mol?1) and branching densities (71–143/1000 C) over a very wide range. The polyethylene branching densities decreased with increasing bulkiness of ligand and decreasing polymerization temperature. Specifically, methyl‐substituted complex 3 showed high activities and produced highly branched amorphous polyethylene (up to 143 branches per 1000 C). |
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| Keywords: | α ‐diimine nickel complex ethylene polymerization highly branched para‐phenyl steric effect |
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