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Journal ArticleDOI

Polymerization of olefins with homogeneous zirconocene/alumoxane catalysts

01 Jan 1988-Polyhedron (Pergamon)-Vol. 7, pp 2375-2381
TL;DR: In this paper, the homogeneous Ziegler-Natta catalyst, consisting of zirconocene compounds and methylalumoxane, leads to extremely high polymerization activities, and polyethylene with activities up to 40 x 106 g PE/g Zr·h is formed.
About: This article is published in Polyhedron.The article was published on 1988-01-01. It has received 124 citations till now. The article focuses on the topics: Polymerization & Hexene.
Citations
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Journal ArticleDOI
TL;DR: Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.
Abstract: One of the most exciting developments in the areas of catalysis, organometallic chemistry, and polymer science in recent years has been the intense exploration and commercialization of new polymerization technologies based on single-site and metallocene coordination olefin polymerization catalysts.1 The vast number of specifically designed/synthesized transition metal complexes (catalyst precursors) and main-group organometallic compounds (cocatalysts) allows unprecedented control over polymer microstructure, the generation of new polymer architectures, and the development of new polymerization reactions. Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.2-4 The intense industrial activity in the field and the challenges to our basic understanding that have come to light have in turn 1391 Chem. Rev. 2000, 100, 1391−1434

1,719 citations

Journal ArticleDOI
TL;DR: In this article, a new range of metallocene catalysts, Cp 2 MCl 2 (M = Ti, Zr, Hf) has been developed in the past decade, which, in the presence of alumoxanes are highly efficient at polymerizing α-olefins (ethene, propene, etc.).

464 citations

Journal ArticleDOI
TL;DR: In this paper, the development of the metallocene/MAO-catalysts from their discovery to their present state-of-the-art is presented, and a better understanding of the mechanism of olefin polymerization leads to findings of other new single site catalysts.
Abstract: 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. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3911–3921, 2004

322 citations

References
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Book ChapterDOI
TL;DR: In this article, the authors discuss the scope of Ziegler catalysis, stereoselectivity, kinetics, and mechanism of homogeneous Natta catalysts; and side reactions in homogeneous catalysts.
Abstract: Publisher Summary This chapter discusses the scope of Ziegler catalysis; stereoselectivity, kinetics, and mechanism of Ziegler catalysis; homogeneous Ziegler–Natta catalysts; and side reactions in homogeneous catalysts. Ziegler catalysis involves rapid polymerization of ethylene and α-ole-fins with the aid of catalysts based on transition-element compounds, normally formed by the reaction of a transition-element halide or alkoxide or alkyl or aryl derivative with a main-group element alkyl or alkyl halide. There are thousands of patents involving every combination of pure or mixed main-group alkyls with transition-element compounds, each claiming advantages. The result of the early work led to the development of “second-generation” Ziegler catalysts. Polymers produced with unmodified Ziegler catalysts showed extremely high molecular weight and broad distribution, and in some cases, there was evidence for “living polymer.” All homogeneous catalyst systems for ethylene polymerization become heterogeneous when polyethylene is formed. On using vanadium-based homogeneous catalysts, polymers consisting of syndiotactic stereo blocks and stereo-irregular blocks are obtained. Very high stereoselectivity is observed for racemic 4-methyl- 1-hexene and racemic 3,7-dimethyl-1-octene, where the asymmetric carbon atom is in the α-position relative to the double bond. Stereoselectivity is caused by the chirality of the catalytically active center, and not by chiral atoms in the growing chain. It must be concluded from the results that reactions take place, which change the number of active sites present, due to the different behavior of the polymers in solution. Study of these new catalysts is intensive. After a short induction period, the activity of polymerization increases as a function of the monomer concentration.

810 citations

Journal ArticleDOI
TL;DR: In this article, a polypropene isotactique avec des catalyseurs de Ziegler-Natta solubles, determination de la microstructure stereochimique et information concernant le mecanisme de reaction
Abstract: Obtention de polypropene isotactique avec des catalyseurs de Ziegler-Natta solubles, determination de la microstructure stereochimique et information concernant le mecanisme de reaction

779 citations

Journal ArticleDOI
TL;DR: In this paper, a synthesis for racemic ethylene-bis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride is described.

452 citations