Polymerization of propylene catalyzed by α-diimine nickel complexes/methylaluminoxane: catalytic behavior and polymer properties

Pourtaghi-Zahed, Hamid; Zohuri, Gholamhossein

doi:10.1007/s00289-013-0920-5

Cited by 12 publications

(11 citation statements)

References 27 publications

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“…Due to the high catalytic activity of the catalyst BNC 4 , further studies have been focused on this catalyst. The effect of polymerization temperature and kinetics study of polymerization on the catalyst behavior (Table ) confirmed the fact that polymerization temperature can enhance the catalyst performance through increasing in the kinetic energy of molecules which facilitates transfer of the monomer to the catalytic active centers and increasing alkylation reaction of metal centers (until 42 °C) . Polymerization temperature higher than 42 °C can cause irreversible deactivation of the active centers (chemical effect) and the reducing of solubility of monomer in solvent as a physical function to reduce activity of the catalyst .…”

Section: Resultsmentioning

confidence: 67%

Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

Khoshsefat

Zohuri

Ramezanian

et al. 2016

J. Polym. Sci. Part A: Polym. Chem.

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A novel series of homo‐, bi‐, and mononuclear Ni(II)‐based catalysts (BNCn n = 1–4, MNC4) were used for ethylene polymerization. The optimum conditions for the catalyst BNC4 (the highest catalytic activity) was obtained at [Al]/[Ni]=2000/1, Tp = 42 °C, and tp = 20 min that was 1073 g PE/mmol Ni h. In theoretical study, steric and electronic effects of substituents and diimine backbone led to prominent influence on the catalyst behavior. The highest MV was resulted from polymerization using BNC4; however, the highest unsaturation content was obtained from BNC1. GPC analysis showed a broad MWD (PDI = 17.8). BNC1 and BNC2 in similar structures showed broad peaks in DSC thermogram, while BNC3 and BNC4 with more electronic effects showed a peak along with a wide shoulder. Monomer pressure increasing showed enhancing in activity of the BNC4, meanwhile a peak with shoulder to a single peak in DSC thermogram and uniformity in morphology of the resulted polymer were observed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3000–3011

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Section: Resultsmentioning

confidence: 67%

Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

Khoshsefat

Zohuri

Ramezanian

et al. 2016

J. Polym. Sci. Part A: Polym. Chem.

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“…The prepared catalyst showed high thermal stability as evidenced by the highest activity at 90 °C. Study of the effect of polymerization temperature and kinetics of polymerization on the catalyst behaviour revealed that the polymerization temperature can enhance the catalyst efficiency through increasing the kinetic energy of the monomer molecules which facilitates transfer of ethylene to the catalytic active centres and also increasing alkylation of metal centres . The activity of the catalyst was increased by increasing the monomer pressure up to 3.5 bar; however, further increase of the monomer pressure led to a decrease of the catalyst activity.…”

Section: Resultsmentioning

confidence: 99%

“…Chain‐walking mechanism of nickel‐ and palladium‐based complexes allows them to produce polymers with a broad spectrum of branching topologies, ranging from relatively linear to hyperbranched or dendritic . The control of polymer topology through chain walking mechanism in the polymerization process offers great opportunities in the development of novel polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

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Single and binary catalyst systems based on nickel and palladium in polymerization of ethylene

Kimiaghalam

Nasr‐Isfahani

Zohuri

et al. 2017

Applied Organom Chemis

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The catalyst (N,N‐bis(2,6‐dibenzhydryl‐4‐ethoxyphenyl)butane‐2,3‐diimine)nickel dibromide, a late transition metal catalyst, was prepared and used in ethylene polymerization. The effects of reaction parameters such as polymerization temperature, co‐catalyst to catalyst molar ratio and monomer pressure on the polymerization were investigated. The α‐diimine nickel‐based catalyst was demonstrated to be thermally robust at a temperature as high as 90 °C. The highest activity of the catalyst (494 kg polyethylene (mol cat)−1 h−1) was obtained at [Al]/[Ni] = 600:1, temperature of 90 °C and pressure of 5 bar. In addition, the performance of a binary catalyst using nickel‐ and palladium‐based complexes was compared with that of the corresponding individual catalytic systems in ethylene polymerization. In a study of the catalyst systems, the average molecular weight and molecular weight distribution for the binary polymerization were between those for the individual catalytic polymerizations; however, the binary catalyst activity was lower than that of the two individual ones. The obtained polyethylenes had high molecular weights in the region of 105 g mol−1. Gel permeation chromatography analysis showed a narrow molecular weight distribution of 1.44 for the nickel‐based catalyst and 1.61 for the binary catalyst system. The branching density of the polyethylenes generated using the binary catalytic system (30 branches/1000 C) was lower than that generated using the nickel‐based catalyst (51/1000 C). X‐ray diffraction study of the polymer chains showed higher crystallinity with lower branching of the polymer obtained. Also Fourier transform infrared spectra confirmed that all obtained polymers were low‐density polyethylene.

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“…for polymerization reactions chromium(III) and nickel(II). [7][8][9][10][11] Combining bipyridine and diazadiene in one bridging scaffold therefore is an appealing target ( Figure 1). Synthetic access to this compound class (1,10-phenanthroline-5,6-diphenyldiazadienes) by condensation of 1,10-phenanthroline-5,6-dione with anilines has been investigated since the early 1990's.…”

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Novel phenanthroline–diaryldiazadiene ligands with heteroditopic coordination spheres

et al. 2015

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1,10-Phenanthroline-5,6-diaryldiazadienes are key structures for the development of novel heterodinuclear photocatalysts and for the construction of extended heterocycles of potential biological use. Herein, the first examples of this compound family are presented together with a wide range of initial reactivity studies. Synthetic strategies are presented to access the two first derivatives of the ligand and to accomplish subsequent metal coordination to the phenanthroline sphere.

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Polymerization of propylene catalyzed by α-diimine nickel complexes/methylaluminoxane: catalytic behavior and polymer properties

Cited by 12 publications

References 27 publications

Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

Polymerization of ethylene using a series of binuclear and a mononuclear Ni (II)‐based catalysts

Single and binary catalyst systems based on nickel and palladium in polymerization of ethylene

Novel phenanthroline–diaryldiazadiene ligands with heteroditopic coordination spheres

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