Copolymerization of Alkenes and Polar Monomers by Early and Late Transition Metal Catalysts

Schöbel, A.; Winkenstette, M.; Anselment, T.M.J.; Machat, M.; Rieger, B.

doi:10.1016/b978-0-12-803581-8.01366-7

Cited by 5 publications

(7 citation statements)

References 235 publications

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“…To functionalize these materials, the reaction conditions developed for functionalization of low molecular weight polyethylene (ratio of ethylene monomer: m CPBA:[Ni(Me 4 Phen) 3 ](BPh 4 ) 2 = 100:14.5:14.5 × 10 −3 in DCE, 11.0 M, 80 °C) needed to be adjusted because of the lower solubility of higher molecular weight polyethylenes in DCE. To achieve the appropriate solubility, three approaches were employed: (1) adding a cosolvent (1,2-dichlorobenzene or 1,2,4-trichlorobenzene); (2) conducting the reaction at lower concentrations; and (3) conducting the reactions at higher temperatures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The synthesis of functionalized polyolefins is a synthetic goal that has been widely sought. The most straightforward way to incorporate polar functionality along the main chain is the copolymerization of unfunctionalized alkenes with polar monomers. , Free-radical copolymerization of ethylene with polar vinyl monomers (vinyl acetate, methyl acrylate, acrylonitrile, etc.) is well-known and conducted commercially, but these polymerizations form materials with high polydispersity index, a high degree of branching, and a nonuniform distribution of the polar functional groups in the polymer chain .…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Hydroxylation of Polyethylenes

et al. 2017

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Polyolefins account for 60% of global plastic consumption, but many potential applications of polyolefins require that their properties, such as compatibility with polar polymers, adhesion, gas permeability, and surface wetting, be improved. A strategy to overcome these deficiencies would involve the introduction of polar functionalities onto the polymer chain. Here, we describe the Ni-catalyzed hydroxylation of polyethylenes (LDPE, HDPE, and LLDPE) in the presence of mCPBA as an oxidant. Studies with cycloalkanes and pure, long-chain alkanes were conducted to assess precisely the selectivity of the reaction and the degree to which potential C–C bond cleavage of a radical intermediate occurs. Among the nickel catalysts we tested, [Ni(Me4Phen)3](BPh4)2 (Me4Phen = 3,4,7,8,-tetramethyl-1,10-phenanthroline) reacted with the highest turnover number (TON) for hydroxylation of cyclohexane and the highest selectivity for the formation of cyclohexanol over cyclohexanone (TON, 5560; cyclohexanol/(cyclohexanone + ε-caprolactone) ratio, 10.5). The oxidation of n-octadecane occurred at the secondary C–H bonds with 15.5:1 selectivity for formation of an alcohol over a ketone and 660 TON. Consistent with these data, the hydroxylation of various polyethylene materials by the combination of [Ni(Me4Phen)3](BPh4)2 and mCPBA led to the introduction of 2.0 to 5.5 functional groups (alcohol, ketone, alkyl chloride) per 100 monomer units with up to 88% selectivity for formation of alcohols over ketones or chloride. In contrast to more classical radical functionalizations of polyethylene, this catalytic process occurred without significant modification of the molecular weight of the polymer that would result from chain cleavage or cross-linking. Thus, the resulting materials are new compositions in which hydroxyl groups are located along the main chain of commercial, high molecular weight LDPE, HDPE, and LLDPE materials. These hydroxylated polyethylenes have improved wetting properties and serve as macroinitiators to synthesize graft polycaprolactones that compatibilize polyethylene–polycaprolactone blends.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic Hydroxylation of Polyethylenes

et al. 2017

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“…It may be due to the protection of MMA monomer with organoaluminium compound (TiBA) and prevent catalyst from poisoning by heteroatoms in the Ma method. [2,51] Branching densities were calculated according to Equation 2 introduced by Guo et al [71] and Leone et al [72] F I G U R E 5…”

Section: H Nmr Analysis: Comonomer Incorporation and Branching Dementioning

confidence: 99%

“…[1] The nonpolar nature of polyolefins and lack of polar functional groups in the main polymer chains are restrictions of the polymer for several applications. [2] Implying polar groups into microstructures of nonpolar polyolefins enhances adhesion on substrates such as glass or ceramic and miscibility with other polymers, solubility in polar solvent, printability, and so forth. [3,4] The nonpolar-polar copolymers have attracted much attention due to their high-grade properties that make them suitable for multipurpose applications for industries.…”

Section: Introductionmentioning

confidence: 99%

Microstructural study on MMA/1‐hexene copolymers made by mononuclear and dinuclear α‐diimine nickel (II) catalysts

Bagherabadi

Zohuri

Ramezanian

et al. 2020

Applied Organom Chemis

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Homogenous catalytic homopolymerization and copolymerization of 1-hexene (H) with methyl methacrylate (MMA) were carried out in presence of two different types of mononuclear (MNC1 and MNC2) and dinuclear Ni-based catalysts (BNC1 and BNC2). Modified methylaluminoxane was used as cocatalyst due to good reactivity in MMA/H copolymerization. Among the structures, BNC1 showed the highest catalyst activity (6.9 × 10 4 g P. mol −1 Ni. h −1). Although M w of the copolymer made by BNC1 was higher than its mononuclear, molecular weight distribution was broader. The optimum molar ratios for mononuclear and dinuclear were obtained at [Al]/[Ni] = 1,000:1 and [Al]/[Ni] = 1,500:1, respectively. Surprisingly, introduction of MMA (up to [MMA]/[H] = 50:50 molar ratio) into the polymerization solution increased the activity of all catalysts. 1 H NMR analysis study revealed that increasing of MMA in the feed composition raised incorporation of the comonomer into the obtained copolymers. The result was consistent on the calculated reactivity ratio of monomers, using Kelen-Tudos method. In addition, BNC1 (at [MMA]/[H] = 70:30 molar ratio) demonstrated more incorporation of MMA to the main copolymer chain (95.2% mol). On the other side, study on tacticity of the PMMA sample was investigated that showed a distribution of stereoregularity in the order of atactic > > syndiotatic > isotactic (53.2 > 26.7 > 20.1). In addition, for copolymers made by BNC1, an unusual pattern was observed as lower concentration of MMA in the feed (i.e., 30%) led to high isotactic blocks of MMA. The highest branching density of the polymer, however, was obtained by BNC1 (217/1000C) and the lowest by BNC2 (80/1000C). Higher extent of the polar comonomer (MMA) in the copolymer backbone led to increasing of T g for the copolymer samples (from 74.4 to 98.9 C). The structural properties of the obtained copolymers were investigated using both Fourier transform infrared spectroscopy and Raman spectroscopies, as well.

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“…In creating polar polyolefin materials, industrially successful early transition metal catalysis has only achieved limited success, mainly due to high catalyst oxophilicity/Lewis acidity and typical polar comonomer Lewis basicity [5][6][7]. In contrast, late transition metal (Ni, Pd) catalysts exhibit far greater polar comonomer tolerance [1,2,8], which enables copolymerizations with a variety of polar comonomers.…”

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confidence: 99%