Handbook of Transition Metal Polymerization Catalysts (original) (raw)
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Catalysts for olefins polymerization
Catalysis Today, 1998
Polyole®ns are still protagonist of an exciting innovation, due to a continuous development of new catalysts, processes and products. The positive solutions given by polyole®ns to the environmental and energetic issues are among the factors responsible for their success. The most relevant breakthrough occurred in the last years is the discovery of metallocenes, and more in general, of single centre catalysts. They are, in most cases, highly active catalysts and are already employed on the industrial scale for the preparation of both``drop-in'' products with improved properties, and of totally new materials. # 1998 Elsevier Science B.V. All rights reserved.
Recent Trends in Polyolefins Catalyst Research
Polybloger, 2020
Almost 60 years have passed since K. Ziegler and G. Natta shared the Nobel Prize for the discovery of olefin polymerization by transition metals. G. Natta proposed and E. Arlman and P. Cossee elaborated the insertion mechanism (IM), which has been generally accepted. However, IM has generated many open questions. In the previous six decades almost a thousand researchers, in hundreds of laboratories worldwide, have performed perhaps a million experiments using very sophisticated equipment and research methods in order to find answers to these questions. However, no definite answers have been found. Evidently, some initial and fundamental presumptions are wrong and have to be re-examined. It was done for Phillips CrOx/SiO2, Ziegler-Natta Ti/MgCl2, and Kaminsky metallocene/MAO systems.
Designing late-transition metal catalysts for olefin insertion polymerization and copolymerization
Chemical Communications, 2010
The innovation of polyolefin with unique architecture, composition and topology continues to inspire polymer chemists. An exciting recent direction in the polyolefin field is the design of new catalysts based on late-transition metals. In this review, we highlight recent developments in rationally designing late-transition metal catalysts for olefin polymerization. The examples described in this review showcase the power of the design of well-defined late-metal catalysts for tailored polyolefin synthesis, which may usher in a new era in the polymer industry.
Materials, 2014
50 years ago, Karl Ziegler and Giulio Natta were awarded the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds and aluminum-alkyls as co-catalysts. Polyolefins have grown to become one of the biggest of all produced polymers. New metallocene/methylaluminoxane (MAO) catalysts open the possibility to synthesize polymers with highly defined microstructure, tacticity, and steroregularity, as well as long-chain branched, or blocky copolymers with excellent properties. This improvement in polymerization is possible due to the single active sites available on the metallocene catalysts in contrast to their traditional counterparts. Moreover, these catalysts, half titanocenes/MAO, zirconocenes, and other single site catalysts can control various important parameters, such as co-monomer distribution, molecular weight, molecular weight distribution, molecular architecture, stereo-specificity, degree of linearity, and branching of the polymer. However, in most cases research in this area has reduced OPEN ACCESS Materials 2014, 7 5070 academia as olefin polymerization has seen significant advancements in the industries. Therefore, this paper aims to further motivate interest in polyolefin research in academia by highlighting promising and open areas for the future.
Macromolecules, 2003
Vinyl chloride monomer (VCM) has been employed as a chain transfer agent to yield polyolefins with one vinyl end group per chain; subsequent incorporation of these macromonomers has resulted in the formation of branched polyolefins. The use of VCM as a comonomer in transition-metalcatalyzed olefin polymerizations results in -chloride elimination, yielding polymers that contain vinyl end groups and a chlorinated catalyst. Through reactivation of the catalyst by advantageous MAO, or other aluminum alkyl, reinitiation of the olefin polymerization can occur; the combination of elimination and reactivation allows for VCM to behave as a chain transfer agent. The use of VCM as a chain transfer agent results in the exclusive formation of vinyl end groups (no vinylidene or internal vinyl end groups) in polyethylenes, both homopolyethylene and copolymers with octene; in propylene polymerizations, vinyl end groups are formed in addition to vinylidene end groups, the result of -hydride elimination which occurs even in the absence of VCM. The chain transfer constants for VCM in ethylene polymerizations for a variety of single site catalysts were determined and found to be very similar, with C s × 10 4 ∼ 30; for a propylene polymerization using a zirconocene catalyst, Cs × 10 4 ∼ 700. It was further observed that the resulting macromonomers formed in the polyethylene polymerizations could be incorporated into the growing polymer chains, resulting in the formation of long chain branches. † Current address: The Dow Chemical Co., Advanced Electronic Materials,
Recent advances in thermally robust, late transition metal-catalyzed olefin polymerization
Polymer International, 2018
Olefin polymerization catalysts employing late transition metals, such as Ni, Pd, Fe, and Co, have been heavily investigated since their discovery in the mid 1990's. Despite the advantages and appeal these catalysts have displayed in academic research, their implementation in industry has remained limited due to a variety of limitations and drawbacks. One specific limitation is the relative thermal instability of most late transition metal olefin polymerization catalysts at the temperatures commonly utilized for industrial polymerizations. This review focuses on the development of Ni-, Pd-, Fe-, and Co-based olefin polymerization catalysts that display increased thermal stability at super-ambient reaction temperatures. These advances in thermal stability have been realized using a variety of ligand modifications, and their polymerization activities and thermal stability are summarized herein. Lastly, a brief outlook on the future of thermally stable, late transition metal olefin polymerization catalysts is provided.