Concerted steric and electronic effects on α-diimine nickel- and palladium-catalyzed ethylene polymerization and copolymerization

Qasim, Muhammad; Tan, Chen; Chen, Changle

doi:10.1016/j.scib.2019.11.019

Cited by 127 publications

(71 citation statements)

References 53 publications

(75 reference statements)

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“…In the field of polyolefin research [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], many studies have reported on the homopolymerization of ethylene [ 21 , 22 , 23 , 24 ], different higher 1-alkene [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ], and linear internal alkenes [ 32 , 33 , 34 ] using Brookhart-type α-diimine nickel and palladium catalysts [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ] because of the chain-walking process [ 42 , 43 , 44 , 45 ]. The interest in highly branched polyolefins such as dendrimer and hyper branched polymers has increased obviously in recent years owing to these unique physical properties, chemical properties, and their potential applications as adhesives, lubricants, and paints [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

Behzadi

et al. 2020

Polymers

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Homo- and copolymers of propylene and 1-decene were synthesized by controlled chain-walking (co)polymerization using phenyl substituted α-diimine nickel complexes activated with modified methylaluminoxane (MMAO). This catalytic system was found to polymerize propylene in a living fashion to furnish high molecular weight ethylene-propylene (EP) copolymers. The copolymerizations proceeded to give high molecular weight P/1-decene copolymers with narrow molecular weight distribution (Mw/Mn ≈ 1.2), which indicated a living nature of copolymerization at room temperature. The random copolymerization results indicated the possibility of precise branched structure control, depending on the polymerization temperature and time.

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Section: Introductionmentioning

confidence: 99%

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

Behzadi

et al. 2020

Polymers

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“…Single crystals of catalysts Pd1 and Pd2 were obtained in DCM with the layering of n-hexane while complex Pd3 and Pd4 also in DCM, but with the slow diffusion of diethyl ether. The molecular structures were determined by X-ray diffraction (Figure 1), with observed bond lengths and bond angles typically for previously reported α-diimine palladium complexes [42][43][44][45][46][47][48][49][50]. The palladium center with square planner geometry has been observed in all of the complexes.…”

Section: Resultsmentioning

confidence: 81%

“…Furthermore, the N-Pd-N bite angle was comparable in all of catalysts, ranging from 77.4° to 77.9°. The palladium complexes were prepared by stirring the ligands with (COD)PdMeCl (COD = 1,5-cyclooctadiene) in dichloromethane (DCM) for 3-4 days at room temperature (Scheme 1) [46][47][48][49][50]. The formations of the metal complexes were confirmed by 1 H NMR, 13 C NMR, COSY, HSQC, and MALDI-TOF-MS. Pd1 was observed in two isomeric forms with respect to the orientation of methyl and chloride attached with palladium in unsymmetrical α-diimine system.…”

Section: Resultsmentioning

confidence: 99%

“…These α-diimine Pd catalysts can produce polyolefins with branched even branch-on-branch structures while using ethylene as the only monomer via the "chain-walking" polymerization mechanism [35][36][37][38][39][40], providing a unique approach for modulating the polyolefin microstructures [41]. However, most α-diimine Pd catalysts exhibit poor thermal stability at high temperatures (>60 • C) due to decomposition reactions that are associated with C-H activation of ligand, associative chain transfer, and bisligation of M-H species, which has limited their practical applications [42][43][44][45][46][47][48][49][50]. It was demonstrated that the formation of a rigid conformation can keep the N-aryl bonds from rotation and, consequently, improve the thermal stabilities of α-diimine Pd catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…Chart 1. Selected Brookhart-type α-diimine Pd catalysts (A) [32], (B) [51,52], (C) [53][54][55], (D) [46][47][48][49][50], (E) [60][61][62] and (F) Pd catalysts synthesized in this work.…”

Section: Introductionmentioning

confidence: 99%

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Ortho-Functionalized Dibenzhydryl Substituents in α-Diimine Pd Catalyzed Ethylene Polymerization and Copolymerization

et al. 2020

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Sterically bulky diarylmethyl-based ligands have received increasing attention in the field of late-transition-metal catalyzed olefin polymerization. Ortho-substituents may have a significant impact on the performance of diarylmethyl-based α-diimine Pd catalysts. In this contribution, a series of α-diimine Pd catalysts bearing ortho-methoxyl/hydroxyl functionalized dibenzhydryl units were prepared, characterized, and investigated in ethylene polymerization and copolymerization with methyl acrylate (MA). The catalytic performances were improved by introducing more ortho-substituents. The catalysts exhibited good thermal stabilities at high temperatures, producing branched polyethylenes. The catalysts bearing hydroxyl groups possessing intramolecular H-bonding, resulted in slightly higher incorporation ratios of MA unit when compared with the catalysts bearing methoxyl groups.

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A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

Dai

Chen

2020

Angewandte Chemie

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The polyolefin industry is dominated by gas‐phase and slurry‐phase polymerization using heterogeneous catalysts. In contrast, academic research is focused on homogeneous systems, especially for late‐transition‐metal catalysts. The heterogenization of homogeneous catalysts is a general strategy to provide catalyst solutions for existing industrial polyolefin synthesis. Herein, we report an alternative, potentially general strategy for using homogeneous late‐transition‐metal catalysts in gas‐phase and slurry‐phase polymerization. In this self‐supporting strategy, catalysts with moderate chain‐walking capabilities produced porous polymer supports during gas‐phase ethylene polymerization. Chain walking, in which the metal center can move up and down the polymer chain during polymerization, ensures that the metal center can travel along the polymer chain to find suitable sites for ethylene enchainment. This strategy enables simple heterogenization of catalysts on solid supports for slurry‐phase polymerization. Most importantly, various branched ultra‐high‐molecular‐weight polyethylenes can be prepared under various polymerization conditions with proper catalyst selection.

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Concerted steric and electronic effects on α-diimine nickel- and palladium-catalyzed ethylene polymerization and copolymerization

Cited by 127 publications

References 53 publications

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

Ortho-Functionalized Dibenzhydryl Substituents in α-Diimine Pd Catalyzed Ethylene Polymerization and Copolymerization

A Self‐Supporting Strategy for Gas‐Phase and Slurry‐Phase Ethylene Polymerization using Late‐Transition‐Metal Catalysts

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