Copolymerization of ethylene/unsaturated alcohols using nickel catalysts: effect of the ligand on the activity and comonomer incorporation

Fernandes, Susete N.; Soares, Ana M. S.; Lemos, F.; Lemos, M.A.N.D.A.; Mano, João F.; Maldanis, Richard J.; Rausch, Marvin D.; Chien, James C. W.; Marques, M. Manuel B.

doi:10.1016/j.jorganchem.2004.10.033

Cited by 20 publications

(27 citation statements)

References 25 publications

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“…the most active system (1‐Br/MAO) leads to the least branched polymers while the less active one (3‐Br/MAO) affords the most branched PEs. Similar results have been reported for PE obtained by us with α‐diimine Ni complexes activated either by MAO23 or DEAC24 in contrast to results obtained by others 25…”

Section: Resultssupporting

confidence: 91%

Ethylene polymerisation by Ni–diphosphine azine complexes

Carvalho¹,

Čermák

Fernandes

et al. 2007

Polymer International

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The properties of [NiX(PR2CH2C(But)NNC(But)CH2PR2)]+ complexes (where X = Br, and R = cyclohexyl (Cy), isopropyl (Pri), tert‐butyl (But), phenyl (Ph); X = Cl or I, and R = cyclohexyl) as catalysts for the polymerisation of ethylene were evaluated with or without the co‐catalysts methylaluminoxane (MAO), diethylaluminium chloride, trimethylaluminium or tri(isobutyl)aluminium. Their efficiency depends on the characteristics of the halogen (X) and the R group of the diphosphine azine ligand. Bromide (X) strongly enhances the catalytic properties of the complexes within the R order Cy > Pri > Ph > But. Temperature, co‐catalyst ratio (Al/Ni) and complex concentration also influence the catalytic activity. The best results were obtained with [NiBr{PCy2CH2C(But)NNC(But)CH2PCy2}]Br activated by MAO (A = 25.8 kg (mol Ni)−1 bar−1 h−1). The polymers were characterised using NMR and differential scanning calorimetry as branched polyethylenes, the number of branches increasing with the temperature of polymerisation. The molecular weights of the polymers were estimated using NMR. A proposal for the catalyst active precursor is made on the basis of experimental data and molecular orbital calculations. Copyright © 2007 Society of Chemical Industry

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Section: Resultssupporting

confidence: 91%

Ethylene polymerisation by Ni–diphosphine azine complexes

Carvalho¹,

Čermák

Fernandes

et al. 2007

Polymer International

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“…Different cocatalysts have been studied previously in the activation of the catalyst precursor 1. DEAC and MAO had been shown to be the best ones for this system in the polymerization of ethylene 28. The PE obtained with this catalyst system is a branched polymer (N branches/1000C = 34 in the case of MAO, RT; 45 in the case of DEAC, RT and 92 in the case of DEAC, T = 60°C).…”

Section: Resultsmentioning

confidence: 95%

“…Calculations similar to those performed with the unsaturated alcohols28 were also carried out with this system. Two modes of AA insertion were studied.…”

Section: Resultsmentioning

confidence: 99%

“…In fact, Ni and Pd complexes with bulky diimine ligands showed improved tolerance against polar functionality24–27 due to the typically lower Lewis acidity of these late transition metals. However, even with these catalysts, a rather significant loss in activity was observed in the presence of the polar monomers 25–28. To get a better performance of the catalyst in the presence of polar functionalities, α‐diimine Ni complexes with electron releasing para‐substituents were synthesized 29, 30.…”

Section: Introductionmentioning

confidence: 99%

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Copolymerization of ethylene with unsaturated alcohols and methylmethacrylate using a silylated α‐diimine nickel catalyst: Molecular modeling and photodegradation studies

Matos

Fernandes

Liu

et al. 2012

J of Applied Polymer Sci

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In this article, the experimental results obtained in the copolymerization of ethylene with polar monomers using a silylated α‐diimine nickel catalyst are described and compared with those obtained with a non‐silylate similar one. The results show that the introduction of a siliyl group in the para‐position of the imine moiety turns the catalyst less sensitive toward polar functionalities. However, the reactivity observed in copolymerization reactions was found to be reduced both the global polymerization and incorporation rates. Molecular modeling calculation allowed us to understand both the preferred insertion mode and the intermediate product structures for E/MMA copolymerization. Photodegradation studies showed that the presence of polar groups in the copolymers increases their rate of oxidation and turn them more easily degradable. The stabilization performed by Tinuvin 770 showed that for long‐exposure times, it is not very effective regardless it is only mixed or grafted to the copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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“…[1][2][3][4] Among them, Nickel complexes have been extensively studied. Ni(II)a-diimine catalysts, when activated with methylaluminoxane (MAO), exhibit high activity towards the polymerization of ethylene, 1-hexene, and propylene as well as their block copolymerization.…”

Section: Introductionmentioning

confidence: 99%

Copolymerization of methyl methacrylate with 4‐vinylpyridine initiated by a novel Ni(II)α‐Benzoinoxime complex

Harrar-Ferfera

2007

J of Applied Polymer Sci

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Copolymerizations of methyl methacrylate (MMA) with 4-vinylpyridine (4VP) were performed from different monomer feed ratios in 1,4-dioxan at 308C under free radical initiation experimental conditions, using Ni(II)a-Benzoinoxime complex as initiator. The obtained copolymers (PMMA4VP) were examined by FTIR and 1 H NMR spectroscopies. The composition of these copolymers was calculated, using 1 H NMR spectra and elemental analysis. Monomer reactivity ratios were estimated from Fineman-Ross (FR, r m 5 0.550, r v 5 1.165) and Kelen-Tudos (KT, r m 5 0.559, r v 5 1.286) linearization methods, as well as nonlinear error in variables model (EVM) method using the RREVM computer program (RREVM, r m 5 0.559, r v 5 1.264). These values suggest that MMA-4VP pair copolymerizes randomly. 1 H NMR spectra provide information about the stereochemistry of the copolymers in terms of sequence distributions and configurations. These results showed that the age of the Ni complex has an impact not only on its activity towards polymerization reactions but also on the features of the corresponding copolymers, whereas the chemical composition was insensitive to this prominent factor. The mechanism of MMA-4VP copolymerization is consistent with a radical process as supported by microstructure and molecular weight distribution studies. Thermal behaviours of these copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis.

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Copolymerization of ethylene/unsaturated alcohols using nickel catalysts: effect of the ligand on the activity and comonomer incorporation

Cited by 20 publications

References 25 publications

Ethylene polymerisation by Ni–diphosphine azine complexes

Ethylene polymerisation by Ni–diphosphine azine complexes

Copolymerization of ethylene with unsaturated alcohols and methylmethacrylate using a silylated α‐diimine nickel catalyst: Molecular modeling and photodegradation studies

Copolymerization of methyl methacrylate with 4‐vinylpyridine initiated by a novel Ni(II)α‐Benzoinoxime complex

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