Noncovalent Interactions in Late Transition Metal-Catalyzed Polymerization of Olefins

Macromolecules, Journal Year: 2024, Volume and Issue: 57(15), P. 6899 - 6913

Published: July 23, 2024

Language: Английский

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Suppression of Chain Walking and Chain Transfer in Ethylene (Co)Polymerization with Iminodibenzyl Substituents Containing Second Coordination Spheres

Macromolecules, Journal Year: 2024, Volume and Issue: 57(11), P. 5262 - 5270

Published: May 29, 2024

Chain walking and chain transfer are the two most important events that determine structure molecular weight of resulting polyolefin in imine-based late transition metal-catalyzed ethylene (co)polymerization. In this study, we have demonstrated nitrogen-containing iminodibenzyl substituents effective suppression during α-diimine Ni(II)- Pd(II)-catalyzed For purpose, several Ni(II) Pd(II) complexes with N-diphenyl or been designed, prepared, described. case nickel-catalyzed polymerization, catalyst exhibited higher activities yielded polyethylenes orders magnitude weights than catalyst. Similar observations were also found polymerization copolymerization methyl acrylate catalyzed by corresponding palladium catalysts. Compared to dibenzosuberyl catalysts, catalysts an excellent ability suppress process produced (co)polymers significantly lower branching densities It was proposed observed phenomenon is caused second coordination sphere effects substituents.

Language: Английский

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Stable Ultrahighly Branched Polyethylene Synthesis via Externally Robust Chain-Walking Polymerization

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(17), P. 13531 - 13541

Published: Aug. 27, 2024

Recently, late-transition-metal-catalyzed chain-walking polymerization has emerged as a promising method for synthesizing range of polyethylenes, including linear, branched, and hyperbranched structures, solely from ethylene feedstock. The spatial configuration the catalyst is crucial factor in determining branching patterns observed resulting polyethylene. In this study, we designed employed series stereoscopically bulky α-diimine Ni(II) Pd(II) complexes featuring axial flexible cycloalkyl substituents an equatorial rigid dibenzobarrelene backbone (co)polymerization. These exhibited high catalytic activity, reaching up to 106 g/(mol Ni·h), yielded very-high-molecular-weight polyethylene with extremely narrow molecular weight distributions (1.00–1.27) very densities (105–153/1000C) living behavior under various temperatures. Most interestingly, density cyclohexyl-substituted complex almost independent conditions ultrahighly branched ultrahigh (up 1097 kg/mol) can be accessed. On other hand, corresponding also demonstrated moderate achieving 105 Pd·h), highly weights ranging 160.8 511.9 kg/mol. Moreover, these were capable generating high-molecular-weight E-MA copolymers adjustable incorporation ratios (0.85–2.77 mol %) (106–117/1000C). Through comparative analysis single-crystal structures DFT calculations, found that create interesting ligand environment favors chain walking over propagation nickel-catalyzed system. This finding provides valuable insights into design more efficient controllable catalysts synthesis polyethylenes tailored properties.

Language: Английский

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Direct synthesis of poly(α-olefin) thermoplastic elastomers via controlled chain straightening using bulky α-diimine palladium complexes

Polymer Chemistry, Journal Year: 2024, Volume and Issue: 15(30), P. 3027 - 3039

Published: Jan. 1, 2024

This study uses chain-walking bulky α-diimine Pd( ii ) complexes for α-olefin homopolymerization, generating TPEs with high MW, varied branching, and excellent strain/recovery, highlighting catalyst structure's impact.

Language: Английский

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