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Article

Iminopyridine Ni(II) Catalysts Affording Oily Hyperbranched Ethylene Oligomers and/or Crystalline Polyethylenes Depending on the Reaction Conditions: Possible Role of In Situ Catalyst Structure Modifications

Dipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, Italy
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Academic Editor: Ana María Díez-Pascual
Received: 23 March 2021 / Revised: 23 April 2021 / Accepted: 28 April 2021 / Published: 7 May 2021
Nickel-based ethylene polymerization catalysts have unique features, being able to produce macromolecules with a variable content of branches, resulting in polymers ranging from semicrystalline plastics to elastomers to hyperbranched amorphous waxes and oils. In addition to Brookhart’s α-diimine catalysts, iminopyridine Ni(II) complexes are among the most investigated systems. We report that Ni(II) complexes bearing aryliminopyridine ligands with bulky substituents both at the imino moiety and in the 6-position of pyridine afford either hyperbranched low molecular weight polyethylene oils or prevailingly linear crystalline polyethylenes or both, depending on the ligand structure and the reaction conditions. The formation of multiple active species in situ is suggested by analysis of the post-polymerization catalyst residues, showing the partial reduction of the imino function. Some related arylaminopyridine Ni(II) complexes were also synthesized and tested, showing a peculiar behavior, i.e., the number of branches of the produced polyethylenes increases while ethylene pressure increases. View Full-Text
Keywords: olefin polymerization; nickel; catalysts olefin polymerization; nickel; catalysts
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MDPI and ACS Style

D’Auria, I.; Saki, Z.; Pellecchia, C. Iminopyridine Ni(II) Catalysts Affording Oily Hyperbranched Ethylene Oligomers and/or Crystalline Polyethylenes Depending on the Reaction Conditions: Possible Role of In Situ Catalyst Structure Modifications. Macromol 2021, 1, 121-129. https://0-doi-org.brum.beds.ac.uk/10.3390/macromol1020010

AMA Style

D’Auria I, Saki Z, Pellecchia C. Iminopyridine Ni(II) Catalysts Affording Oily Hyperbranched Ethylene Oligomers and/or Crystalline Polyethylenes Depending on the Reaction Conditions: Possible Role of In Situ Catalyst Structure Modifications. Macromol. 2021; 1(2):121-129. https://0-doi-org.brum.beds.ac.uk/10.3390/macromol1020010

Chicago/Turabian Style

D’Auria, Ilaria, Zeinab Saki, and Claudio Pellecchia. 2021. "Iminopyridine Ni(II) Catalysts Affording Oily Hyperbranched Ethylene Oligomers and/or Crystalline Polyethylenes Depending on the Reaction Conditions: Possible Role of In Situ Catalyst Structure Modifications" Macromol 1, no. 2: 121-129. https://0-doi-org.brum.beds.ac.uk/10.3390/macromol1020010

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