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
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 cat...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-05-01
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| Series: | Macromol |
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| Online Access: | https://www.mdpi.com/2673-6209/1/2/10 |
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| author | Ilaria D’Auria Zeinab Saki Claudio Pellecchia |
| author_facet | Ilaria D’Auria Zeinab Saki Claudio Pellecchia |
| author_sort | Ilaria D’Auria |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-03-10T08:39:25Z |
| format | Article |
| id | doaj.art-c3a6d419926843fa92907c791eb67a48 |
| institution | Directory Open Access Journal |
| issn | 2673-6209 |
| language | English |
| last_indexed | 2024-03-10T08:39:25Z |
| publishDate | 2021-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Macromol |
| spelling | doaj.art-c3a6d419926843fa92907c791eb67a482023-11-22T08:24:54ZengMDPI AGMacromol2673-62092021-05-011212112910.3390/macromol1020010Iminopyridine Ni(II) Catalysts Affording Oily Hyperbranched Ethylene Oligomers and/or Crystalline Polyethylenes Depending on the Reaction Conditions: Possible Role of In Situ Catalyst Structure ModificationsIlaria D’Auria0Zeinab Saki1Claudio Pellecchia2Dipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, ItalyDipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, ItalyDipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, ItalyNickel-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.https://www.mdpi.com/2673-6209/1/2/10olefin polymerizationnickelcatalysts |
| spellingShingle | Ilaria D’Auria Zeinab Saki Claudio Pellecchia 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 olefin polymerization nickel catalysts |
| title | 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 |
| title_full | 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 |
| title_fullStr | 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 |
| title_full_unstemmed | 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 |
| title_short | 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 |
| title_sort | 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 |
| topic | olefin polymerization nickel catalysts |
| url | https://www.mdpi.com/2673-6209/1/2/10 |
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