Effect of Co- and Non-Copolymerizable Lewis Bases in Propylene Polymerization with EtInd2ZrCl2/MAO

Ferreira, M. L.; Belelli, P. G.; Damiani, D. E.

doi:10.1002/1521-3935(20010301)202:6<830::aid-macp830>3.3.co;2-2

Cited by 5 publications

(8 citation statements)

References 9 publications

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“…This effect is particularly important at 383 K. However, at a polymerization temperature of 363 K, the activity after the addition of the PDMS macromonomer is partially recovered, and the ethylene consumption shows an increasing trend. This trend has also been found in the polymerization of ethylene with EBI/MAO at a lower temperature (313 K), with EB as an MAO modifier 16…”

Section: Resultssupporting

confidence: 68%

“…However, the copolymerization of ethylene with polar monomers drastically reduces the catalytic activity of the EBI/MAO system because these compounds can react with the cationic zirconium, which is the reactive site of the catalyst. Because the same behavior has been observed for ethyl benzoate (EB) and tetramethylpiperidine, a plausible explanation is that polar monomers behave like Lewis base compounds 16…”

Section: Introductionmentioning

confidence: 65%

See 1 more Smart Citation

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

Ciolino

Galland

Ferreira

et al. 2004

J. Polym. Sci. A Polym. Chem.

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Polyethylene–poly(dimethylsiloxane) copolymers were synthesized in solution from an ethylene monomer and an ω‐vinyl poly(dimethylsiloxane) (PDMS) macromonomer at 363 and 383 K with EtInd2ZrCl2/methylaluminoxane as a catalyst. The copolymers obtained were characterized with Fourier transform infrared spectroscopy, 1H and 13C NMR, size exclusion chromatography, and differential scanning calorimetry. The rheological properties of the molten polymers were determined under dynamic shear flow tests at small‐amplitude oscillations, whereas the physical arrangement of the phase domains was analyzed with scanning electron microscopy (SEM)/energy dispersive X‐ray (EDX). The analysis of the catalyst activity and the resulting polymers supported the idea of PDMS blocks or chains grafted to polyethylene. The changes in the rheological behavior and the changes in the Fourier transform infrared and NMR spectra were in agreement with this proposal. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2462–2473, 2004

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Section: Resultssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 65%

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

Ciolino

Galland

Ferreira

et al. 2004

J. Polym. Sci. A Polym. Chem.

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“…Primary insertion has similar activation energy as secondary insertion, but the primary insertion is exothermic, whereas secondary insertion is endothermic (see Table 7). Activation energies are higher than those from experimental results with propylene in parallel coordination (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) kcal N mol -1 ). These results are in line with the idea of an initial perpendicular coordination of propylene, rather than a parallel one.…”

Section: Propylene Insertionmentioning

confidence: 63%

“…Published results, both theoretical and experimental, have pointed out the importance of the electronic aspects besides the steric ones in olefin polymerization using metallocenes. [23,[33][34][35]…”

Section: Csmentioning

confidence: 99%

A Proposed Mechanism for Olefin Polymerization, 2. EHMO and MM2 Study

Ferreira¹

2002

Macromol. Theory Simul.

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This paper reports the results about the model presented in Part 1 for olefin polymerization with metallocenes, using semiempirical extended Hückel molecular orbital (EHMO) and MM2 methods. The main aspects of the model are analyzed. These are bipyramidal or octahedral coordination, two different olefins coordination and the possibility of different active sites. A model of polymerization for a C2 catalyst, prototypical and with steric hindrance, and for a Cs catalyst was analyzed with MM2 to evaluate steric effects. The electronic effects were modeled using MAO to determine the feasibility of the model. Models for ethylene and propylene coordination and insertion were considered. The insertion models were only of qualitative value and they were designed to evaluate the effect of a triggering second olefin. A third olefin coordination (polymerizable or not) was considered for C2 and Cs catalysts. Experimental evidence was analyzed with the different aspects of the model.

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“…The catalyst based on dichloride complex A was significantly more active than the corresponding catalysts based on chloroamido complexes B or C. This is a consequence of the Lewis basic [NMe 2 ] or [NEt 2 ] group; amine group is able to interact with MAO and with the formed zirconium cation. [9] It is probable, that the [NR 2 ] groups remain in the neighbourhood of the active site and modify the Zr centre, and they are a poison for some active sites. Using only MAO as cocatalyst the polymerisation proceeded rapidly, but the catalyst also deactivated rapidly.…”

Section: Polymerisationsmentioning

confidence: 99%

Activation and Polymerisation of ansa‐Zirconocene Chloroamido Complexes

Seraidaris¹,

Löfgren²,

Mäkelä-Vaarne

et al. 2004

Macro Chemistry & Physics

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Summary: Propene polymerisation was conducted with three ansa‐zirconocene complexed: Me2Si(2‐Me‐4‐PhInd)2ZrCl2 (A), Me2Si(2‐Me‐4‐PhInd)2ZrClNMe2 (B) and Me2Si(2‐Me‐4‐PhInd)2ZrClNEt2 (C). Methylalumoxane (MAO) or [HNPhMe2][B(C6F5)4] was used as cocatalyst. The influence of cocatalysts and triisobutylaluminum (TIBA) on polymerisation activity, molecular weight and polymer microstructure was studied. Furthermore, the alkylation and activation of the complexes were examined using UV/VIS spectroscopy. Complex A was the most active in polymerisation, but polymers produced by B and C had in general higher molecular weights. Replacing MAO partially by TIBA increased the molecular weight and prevented catalyst deactivation. According to the UV/VIS measurements, all complexes have low reactivity towards TMA and TIBA. Similar cationic species were formed of all three studied zirconocenes in the reaction with MAO. Additional TIBA did not affect the type of active species formed in the reaction of zirconocene and MAO, but increased the activity of B and C.UV/VIS spectrum of complex A with MAO and with a MAO/TIBA mixture.imageUV/VIS spectrum of complex A with MAO and with a MAO/TIBA mixture.

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Effect of Co- and Non-Copolymerizable Lewis Bases in Propylene Polymerization with EtInd2ZrCl2/MAO

Cited by 5 publications

References 9 publications

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

A Proposed Mechanism for Olefin Polymerization, 2. EHMO and MM2 Study

Activation and Polymerisation of ansa‐Zirconocene Chloroamido Complexes

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