Enhancement of Productivity, Molecular Weight and Stereoregularity of 1‐Butene Polymerization by MAO Modification

Fujita, Masayuki; Seki, Yoshinori; Miyatake, Tatsuya

doi:10.1002/macp.200400060

Cited by 15 publications

(15 citation statements)

References 32 publications

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“…As we have already reported, [28,29] the modification of MMAO with water and pentafluorophenol induces not only the reduction of free TMA, which is contained into aluminoxane, but also the change in the steric structure and electronic circumstances of aluminoxane. The steric and electronic properties of W/PM-MMAO are very different from those of the original MMAO, and we propose that W/PM-MMAO interacts more strongly to the cationic metal center of metallocene than does MMAO.…”

Section: Resultsmentioning

confidence: 68%

“…[28,29] The data also revealed that different cocatalysts yield polymers with different structures. The molecular weight of obtained polymers from 3 or 4 with W/PM-MMAO was higher than that of polymers synthesized with MMAO.…”

Section: Resultsmentioning

confidence: 91%

“…Polymerization of propylene was carried out using dimethylsilylenebis(2-methyl-indenyl)zirconium dichloride (3) and dimethylsilylenebis(2-methyl-4-(1-naphthyl)indenyl)zirconium dichloride (4) [4] as C 2 -symmetric ansazirconocenes with MMAO and W/PM-MMAO [28,29] as a cocatalyst at 40 8C ( Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…[17,21,22] We have reported the enhancement of productivity, stereoregularity, and regioregularity as well as increased molecular weight of 1-butene polymerization with a 2,2-thiobis(phenoxy)titanium complex (1) [23][24][25][26] by isobutylmethylaluminoxane (MMAO) modification using water [27] or both water and pentafluorophenol. [28] In these studies, we claim that the addition of water and pentafluorophenol induces the structural and electrical changes in the aluminoxane and the reduction of ''free'' trimethylaluminum (TMA). Furthermore, the same enhancement of productivity, stereoregularity, and regioregularity and increased molecular weight occurs with stereoblock poly(propylene) synthesized with bis(2-phenylindenyl)zirconium dichloride (2) and water/pentafluorophenol-modified MMAO (W/PM-MMAO).…”

Section: Introductionmentioning

confidence: 99%

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Propylene Polymerization Using ansa‐Zirconocenes with Water/Pentafluorophenol‐Modified Methylaluminoxane

Fujita¹,

Seki²,

Miyatake³

2005

Macro Chemistry & Physics

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Summary: We have confirmed that water‐ and pentafluorophenol‐modified isobutylmethylaluminoxane (W/PM‐MMAO) enhances the productivity and stereoregularity of the yielded polymer and increases its molecular weight when propylene is polymerized using C2‐symmetric ansa‐zirconocenes. 13C NMR analysis shows that when W/PM‐MMAO is used as a cocatalyst with C2‐symmetric ansa‐zirconocenes, although the pentad peaks of the stereoerrors derived from enantiofacial misinsertion have still existed; those derived from the epimerization of the growing chain end that occurred with β‐hydride elimination disappear. Therefore, we propose that W/PM‐MMAO interacts more strongly to the cationic metal center of metallocene than does MMAO owing to steric and electronic effect, and W/PM‐MMAO suppresses β‐hydride elimination, resulting in the production of polypropylene with higher molecular weight and isotacticity. To the contrary, there was no significant difference in the structure of the yielded polymer when W/PM‐MMAO was used with Cs‐symmetric ansa‐zirconocenes. In the case of Cs‐symmetric ansa‐zirconocene, the stereoerror is mostly the result of monomer insertion error, and small amount of stereoerror caused by “skipped” insertion, not from the epimerization of the polymer chain end that occurs after β‐hydride elimination; therefore, there might not be any difference of the microstructure of yielded polymers between MMAO and W/PM‐MMAO. It can be concluded that the both cases of C2‐ and Cs‐symmetric ansa‐zirconocenes are used as a catalyst, and water and phenol modification of MMAO does not affect the monomer misinsertion which is one of the mechanisms of the stereoerrors.13C NMR spectra of isotactic PP. (a) Sample 1. (b) Sample 2.magnified image13C NMR spectra of isotactic PP. (a) Sample 1. (b) Sample 2.

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Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Propylene Polymerization Using ansa‐Zirconocenes with Water/Pentafluorophenol‐Modified Methylaluminoxane

Fujita¹,

Seki²,

Miyatake³

2005

Macro Chemistry & Physics

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“…Tritto et al described a new cocatalyst by reaction between aluminium alkyls and compounds having electron withdrawing groups for polymerization of ethylene with higher activity at low ratios of cocatalyst to catalyst . Further, Fujita et al claimed that the addition of pentafluorophenol (PFP) and water to modified MAO could enhance the catalyst activity and stereoregularity along with an increase in molecular weight due to decrease of free trimethylaluminium and changes in the structure of MAO …”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, rheological and thermal behavior of metallocene ethylene − norbornene copolymers with low norbornene content using pentafluorophenol modified methylaluminoxane

Manteghi

Arabi

Jahani

2015

Polymer International

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Ethylene − norbornene copolymers were synthesized using rac-ethylene bis(indenyl) zirconium dichloride/pentafluorophenol modified methylaluminoxane. First, the effect of using a modifier in combination with a low ratio of Al/Zr on the catalyst activity and co-monomer incorporation was studied. The results of copolymerization reveal a 20% co-monomer incorporation improvement and a rise of activity by 2-fold in the presence of the modifier. Rheological measurements show a higher molecular weight in copolymers synthesized using modified methylaluminoxane. The alternative and dyad block microstructures of copolymers become possible in the case of a norbornene content of more than 14 mol%. Second, the effect of co-monomer content on the rheological and thermal behavior of the synthesized copolymers was investigated. The results of the rheological study indicate a lower molecular weight in samples containing a higher norbornene content. Dynamic mechanical thermal analysis confirms the influence of different microstructures on the glass transition temperature. The crystal structure of copolymers having a higher molecular weight is emphasized using wide angle X-ray scattering and DSC even with a greater incorporation of norbornene.

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Single‐Site Catalysts

Heurtefeu

Vaultier

Leino

et al. 2012

Encyclopedia of Polymer Science and Technology

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The recent rapid development of organometallic single‐site catalysts (SSCs) has revolutionized polyolefin research and permitted the production of new specialty polymers and commodity polyolefins with improved properties. These well‐defined catalyst systems generally consist of a transition metal atom, such as titanium, zirconium, hafnium, iron, nickel, or palladium, complexed with an organic ligand set and an initiating group. In most cases, activation with methylaluminoxane or compounds bearing a weakly coordinating anions generates cationic‐active species responsible for olefin coordination and polymer chain growth. Representative examples of SSCs include the bis(cyclopentadienyl) or bis(phenoxyimine)‐type group 4 catalysts as well as the diimine complexes of nickel and palladium. By variation of the organic ligand and thus the steric and electronic environment of the metal center, these catalysts can be tailored to control the olefin polymerization reaction in an unprecedented fashion. Almost any vinyl monomer, irrespective of molecular weight or steric hindrance, can be polymerized by choosing the proper catalyst. Virtually all feasible poly(α‐olefin) microstructures ranging from atactic to isotactic, hemiisotactic, syndiotactic, and stereoblock polymers can be produced by rational modification of the catalyst structure. Functional monomers are readily copolymerized with the less oxophilic late transition metal catalysts. Entirely new materials, not accessible with traditional Ziegler–Natta catalysts, have emerged, including high melting syndiotactic polystyrene and cycloaliphatic polymers. This article provides a broad overview of SSCs and their application in olefin polymerization. Evolution and classification of SSCs, polymerization of ethylene, propylene, as well as functional olefins, macromolecular architecture bearing polyolefin blocks are covered. Finally, heterogenization of SSCs for use in industrial processes is described.

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Enhancement of Productivity, Molecular Weight and Stereoregularity of 1‐Butene Polymerization by MAO Modification

Cited by 15 publications

References 32 publications

Propylene Polymerization Using ansa‐Zirconocenes with Water/Pentafluorophenol‐Modified Methylaluminoxane

Propylene Polymerization Using ansa‐Zirconocenes with Water/Pentafluorophenol‐Modified Methylaluminoxane

Synthesis, characterization, rheological and thermal behavior of metallocene ethylene − norbornene copolymers with low norbornene content using pentafluorophenol modified methylaluminoxane

Single‐Site Catalysts

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