Highly robust iminopyridyl nickel catalysts for the synthesis of polyethylene wax

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Because of its unique properties, polyethylene wax has been widely applied in many fields. In this contribution, several iminopyridyl nickel catalysts are designed and synthesized. The introduction of sterically bulky substituents can significantly enhance the catalytic performances during ethylene polymerization. The generated polyethylene wax is highly branched due to the chain walking characteristic for this system. To further enhance the catalytic behavior of these nickel catalysts, the corresponding supported system is prepared and investigated. The heterogeneous system presents higher activity and higher thermal stability than its homogenous counterpart. Specifically, the nickel catalyst bearing OH moiety is highly robust even at 120 °C with catalytic activity of up to 9.4 × 106 g mol−1 h−1. The molecular weight and microstructure of the generated polyethylene wax can also be affected by ligand substituents and the heterogenization process. This work demonstrates the great potentials of nickel catalysts for the synthesis of polyethylene wax.