Influence of Polyethylene Glycol Unit on Palladium‐ and Nickel‐Catalyzed Ethylene Polymerization and Copolymerization

Zhang, Dan; Chen, Changle

doi:10.1002/ange.201708212

Cited by 20 publications

(6 citation statements)

References 85 publications

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“…The second coordination sphere mechanism greatly influences the properties of α‐diimine‐based nickel and palladium catalysts in ethylene polymerizations, with significant reduction in the polymer branching density. The second mechanism revealed the critical role of the metal–nitrogen interaction in β‐X elimination through ligand modifications by introducing a polyethylene glycol unit to some phosphine‐sulfonate palladium and nickel catalysts . In this study, our polyfluorinated complexes have not yet been used for ethylene polymerization.…”

Section: Introductionmentioning

confidence: 98%

“…For example, the C–H···F–C interaction was previously demonstrated to influence the ethylene polymerization process. There are two types of secondary interaction mechanisms in metal‐catalyzed reactions for the ethylene polymerization process, which has been discussed and demonstrated in some papers . For the first kind of mechanism with C–H···F–C interaction, namely ethylene polymerization, this first kind of secondary interactions may play an important role in transition‐metal‐catalyzed reactions.…”

Section: Introductionmentioning

confidence: 99%

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Studies of two different types of intramolecular C–H···F–C interactions from polyfluorinated diiodometal(II) diimine complexes

Zheng

Lin

et al. 2018

J Chinese Chemical Soc

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The X‐ray crystal structures of the polyfluorinated complexes [5,5′‐bis(HCF2CF2CF2CF2CH2OCH2)‐2,2′‐bpy]MI2 (55‐8F‐PtI2 and 55‐8F‐PdI2 where M = Pt and Pd, respectively) were obtained. These two structures are found to show not only two different types of intramolecular, six‐membered cyclic C–H···F–C interactions (F2C–H···F–C and HC–H···F–C) as important structural features but also alternating fluorinated and non‐fluorinated layers. The F2C–H···F–C interactions, which are close to the metal core, are much better structurally characterized in this type of complexes with fluorous ponytails at the 5,5′ positions than those previously reported at the 4,4′ positions. The molecular planes of (bpy)MI2 are extended by self‐matching, using two C–H···I hydrogen bonds and one C–H···F–C blue‐shifting hydrogen bond. The F2C–H···F–C hydrogen bonds interact at the supramolecular level such that one polyfluorinated ponytail of the title compounds is transoid without an intramolecular C–H···F–C interaction, while the other polyfluorinated ponytail is cisoid with an intramolecular C–H···F–C interaction. Why one ponytail is cisoidal while the other is transoidal will be explained. Furthermore, the second type of C–H···F–C interactions involving the methylene H atom has been identified for the first time. In addition, these two metal structures are studied by density functional theory (DFT).

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Studies of two different types of intramolecular C–H···F–C interactions from polyfluorinated diiodometal(II) diimine complexes

Zheng

Lin

et al. 2018

J Chinese Chemical Soc

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“…The possible interactions between a monomer/polymer chain and the second center are dependent on monomer length and presence of weakly basic substituents such as hydrogen or phenyl in the monomer. [17][18][19][20][21][22][23][24][25][26] This shows the importance of catalyst structure that strongly affects the resulting polymer microstructure. [10][11][12] Whereas a rigid bridge poses the centers at a constant distance, a flexible one could lead to variable distance.…”

Section: Introductionmentioning

confidence: 99%

“…The importance of late transition metal catalysts especially Ni and Pd complexes is in regard to chain walking mechanism and their activity in the copolymerization of polar monomers and production of highly branched polyolefins and thermoplastic elastomers. [17][18][19][20][21][22][23][24][25][26] This shows the importance of catalyst structure that strongly affects the resulting polymer microstructure. [27][28][29][30][31][32][33][34][35] Based on this, dinuclearity effect can control this behavior through the different structures.…”

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confidence: 99%

Cooperative effect through different bridges in nickel catalysts for polymerization of ethylene

Khoshsefat

Dechal

Ahmadjo

et al. 2019

Applied Organom Chemis

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A series of mononuclear (M 1 and M 2 ) and dinuclear (C 1 -C 6 ) Ni α-diimine catalysts activated by modified methylaluminoxane were used in polymerization of ethylene. Catalyst C 2 bearing the optimum bulkiness showed the highest activity (1.6 × 10 6 g PE (mol Ni) −1 h −1 ) and the lowest short-chain branching (32.5/1000 C) in comparison to the dinuclear and mononuclear analogues.Although the mononuclear catalysts M 1 and M 2 polymerized ethylene to a branched amorphous polymer, the dinuclear catalysts led to different branched semicrystalline polyethylenes. Homogeneity and heterogeneity in the microstructure of the polyethylene samples was observed. Different trends for each catalyst were assigned to syn and anti stereoisomers. In addition, thermal behavior of the samples in the successive self-nucleation and annealing technique exhibited different orders and intensities from methylene sequences and lamellae thickness in respect of each stereoisomer behavior. Higher selectivity of hexyl branches obtained by catalyst C 2 showed a cooperative effect between the centers. The results also revealed that for catalysts C 5 and C 6 , selectivity of methyl branches led to very high endotherms and crystalline sequences with melting temperatures higher than that of 100% crystalline polyethylene indicating ethylene/propylene copolymer analogues. For catalysts C 3 and C 4 , more vinyl end groups were a result of the long distance between the Ni centers. Kinetic profiles of polymerization along with a computational study of the precatalysts and catalysts demonstrated that there is a direct relation between rate constant, energy interval of catalyst and precatalyst, and interaction energy of Et···methyl cationic active center (Et···MCC or π-Comp.). Based on this, narrow energy interval (activation energy) of precatalyst and catalyst leads to fast and higher activation rate (catalyst M 2 ), and strong interaction of ethylene and catalyst leads to high monomer uptake and productivity (catalyst C 2 ). Moreover, theoretical parameters including electron affinity, Mulliken charge on Ni, chemical potential and hardness, and global electrophilicity showed optimum values for C 2 .

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“…Typically, these functionalized polyethylenes produced by the most successful late transition nickel and palladium catalysts usually suffer from molecular weights of M n < 10 5 g mol -1 even at high pressures. [46][47][48][49][50][51][52][53][54][55][56][57][58][59] In this contribution, we now show how polar functionalized ultrahigh number-average molecular weight polyethylenes (M n > 10 6 g mol -1 ) can be accessible via the coordination-insertion copolymerization of ethylene with polar monomers using the well-designed -diimine nickel catalysts. Most notably, to address the issue of molecular weight, these reactions proceed at convenient and highly desired ambient conditions of both pressure (1 bar) and temperature (30 o C) in a glass reactor.…”

Section: Introductionmentioning

confidence: 99%

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Kang

Zhang

et al. 2022

CCS Chem

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Direct copolymerization of ethylene with polar monomers to produce polar functionalized polyethylene is the most straightforward and potentially ideal route. However, access to high molecular weights of polar copolymers represents one of the biggest challenges. In this contribution, we report a family of well-designed nickel catalysts that readily address the issue at convenient and highly desired ambient conditions. Under 1 bar at 30 o C, polar functionalized ultrahigh number-average molecular weight polyethylenes (UHMWPE, M n = 825~1102 kg mol -1 ) can directly be generated. The highest average number of incorporated polar units per polymer chain is 122. This enhances copolymer molecular weights with up to two orders of magnitude relative to previous reports. Notably, this nickel catalyst family also exceptionally produces the highest number-average molecular weight polyethylenes (M n = 6037 kg mol -1 ) at 1 bar using the nickel species. The Sterimol B 1 steric parameter of nickel catalyst quantitatively correlates to polymer molecular weight. Mechanistic insights from DFT calculation reveal that the low barrier (10.4 kcal mol -1 ) of ethylene insertion as the rate-limiting step should be responsible for high activity and the formation of UHMWPE. This coordination-insertion approach is strikingly contrast to the high energy free-radical approach.

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Influence of Polyethylene Glycol Unit on Palladium‐ and Nickel‐Catalyzed Ethylene Polymerization and Copolymerization

Cited by 20 publications

References 85 publications

Studies of two different types of intramolecular C–H···F–C interactions from polyfluorinated diiodometal(II) diimine complexes

Studies of two different types of intramolecular C–H···F–C interactions from polyfluorinated diiodometal(II) diimine complexes

Cooperative effect through different bridges in nickel catalysts for polymerization of ethylene

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

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