Preface

Sinn, Hansjörg; Kaminsky, Werner

doi:10.1002/masy.19950970102

Cited by 63 publications

(103 citation statements)

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“…By cryoscopic measurements in benzene or liquid trimethylaluminum, decomposition reactions with water, hydrochloric acid, alcohols, and NMR-measurements, he came to the conclusion that MAO consists of basic units of Al 4 O 3 (CH 3 ) 6 . 56 These units can combine to form cage structures of preferentially 4 units, which could be the active form. Rytter is convinced that three units are sufficient because bridging methyl groups are already existing.…”

Section: Activation Mechanismmentioning

confidence: 99%

The discovery of metallocene catalysts and their present state of the art

Kaminsky

2004

J. Polym. Sci. A Polym. Chem.

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Metallocene and other transition metal complexes activated by methylaluminoxane are highly active catalysts for the polymerization of olefins, diolefins, and styrene, which was discovered at the University of Hamburg about 25 years ago. These catalysts allow the synthesis of polymers with a highly defined microstructure, tacticity, and stereoregularity, as well as new copolymers with superior properties such as film clarity, tensile strength, and lower extractables. A better understanding of the mechanism of olefin polymerization leads to findings of other new single site catalysts. The development of the metallocene/MAO-catalysts from their discovery to their present state of the art is presented. Keywords:metallocene catalysts; methylaluminoxane; olefin polymerization; zirconocene complexes; polyolefins; single site catalysis Dr. Kaminsky received his Ph.D. and degree in chemistry from Hamburg University, Germany in 1971 for investigating the side reactions of biscyclopentadienyl-zirconiumdichloride and triethylaluminum. He then served as lecturer and continued his research on the determination of zirconocene/aluminumalkyl-complexes and recycling of polymers by pyrolysis in a fluidized bed process. During that time he and Hansjörg Sinn discovered that the activity of metallocenes and other transition metals can be increased extremely by the addition of MAO as a cocatalyst. In 1979 he became full professor at the University of Hamburg for Technical and Macromolecular Chemistry and has served as director, dean, and president of German chemical society, Hamburg section. Dr. Kaminsky has received the following honors and rewards: elected to the

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Section: Activation Mechanismmentioning

confidence: 99%

The discovery of metallocene catalysts and their present state of the art

Kaminsky

2004

J. Polym. Sci. A Polym. Chem.

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361

221

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“…2) The MAO samples always contain significant amounts of trimethylaluminium (TMA) (2 -30% with respect to Al) 12,13) , both in a state strongly associated with MAO and in free state. The MAO molecular mass depends on the TMA content and increases as TMA is removed 12) .…”

Section: Introductionmentioning

confidence: 99%

“…1) The MAO molecular mass (oligomerization degree n in structure [ 1Al(CH 3 )O1 ] n ) varies over a wide range (n = 6 -30) and depends on the preparation procedure [10][11][12] . The activity of zirconocene catalysts in ethylene polymerization depends on the MAO oligomerization degree and increases with increasing n value 10,11) .…”

Section: Introductionmentioning

confidence: 99%

A DFT quantum-chemical study on the structures and active sites of polymethylaluminoxane

Захаров

Potapov

et al. 1999

Macromol. Theory Simul.

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SUMMARY:The electronic structure and geometry of polymethylaluminoxane (MAO) [ 1Al(CH 3 )O1 ] n with different size (n = 4 -12) have been studied using quantum-chemical DFT (density functional theory) calculations. It has been found: 1) Starting from n = 6, the three-dimensional oxo-bridged (cage) structure of MAO is more stable than the cyclic structure. 2) Both for cage structure and for cyclic structure the Lewis acidity

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“…Along with the resonance at Ϫ0.20 ppm for MAO with high molecular weight reported in the literature and Sinn's proposition, 12 it will be useful to control the MAO production and exploit the mechanism investigation. 2.…”

Section: Resultsmentioning

confidence: 96%

In situ1H- and27AL-NMR studies on metallocene catalyst systems?Catalysts for olefin polymerization

Zhang¹,

Duan²,

Zheng³

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:The process of partial hydrolysis reaction of TMA with water and the interaction of zirconocene dichloride (Cp 2 ZrCl 2 ) with TMA, MAO, and the in situ partially hydrolyzed products of TMA were studied by in situ Al-NMR spectroscopy. The 1 H-NMR spectra of MAO samples and the in situ hydrolyzed products of TMA with water under different conditions are different. A new peak at ␦ ϭ Ϫ0.58 ppm in 1 H-NMR spectra is observed, and is supposed to be due to the methyl resonance of MAO with low molecular weight. Alkylation reaction is observed between Cp 2 ZrCl 2 and TMA, MAO, and the in situ hydrolyzed products of TMA, and TMA is supposed to be the actual alkylating agent.27 Al-NMR studies show that MAO is tetra-coordinated.

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Preface

Cited by 63 publications

References 0 publications

The discovery of metallocene catalysts and their present state of the art

The discovery of metallocene catalysts and their present state of the art

A DFT quantum-chemical study on the structures and active sites of polymethylaluminoxane

In situ1H- and27AL-NMR studies on metallocene catalyst systems?Catalysts for olefin polymerization

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