Polymerization Catalyst Composition

A high-activity ethylene polymerization catalyst [bis(4-allyl-2,6-diisopropylpheny-limino)acenaphtheno]nickel(ll) dibromide has been prepared. When used in conjunction with methylalumoxanes, high polymers were produced. 

A mixture consisting of acenaphthoquinone (5.5 mmol) and 4-aUyl-2,6-diisopropy-laniline (11.1 mmol) dissolved in 10 ml of acetic acid was refluxed one hour and then cooled to ambient temperature and filtered. The solid was washed with 5 ml of acetic acid, four times with 10 ml of hexane, and dried the product was isolated in 82% yield. 

Preparation of [bis(4-Allyl-2,6-Diisopropylphenylimino)Acenaphtheno] Nickel(II)Dibromide 

Nickel bromide ethylene glycol dimethyl ether (0.25 mmol) and the Step 1 product (0.32 mmol) were combined in a Schlenk flask under an argon atmosphere and 20 ml of CH2CI2 added. The mixture was stirred 24 hours at ambient temperature and then concentrated. The residue was washed three times with 10 ml of diethyl ether and dried the product was isolated as a dark-red powder in 85% yield. 

The Step 2 product was added to a flame-dried Schlenk flask with a stirrer and then backfilled three times with ethylene and 50 ml of toluene added. Stirring was begun, and methyl alumoxane dissolved in heptane added by syringe. After 30 minutes the reaction was quenched with acidified ethanol, filtered, dried in vacuum at 40° C for 10 hours, and the product was isolated. 

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Dicyclopentadiene is also polymerized with tungsten-based catalysts. Because the polymerization reaction produces heavily cross-Unked resins, the polymers are manufactured in a reaction injection mol ding (RIM) process, in which all catalyst components and resin modifiers are slurried in two batches of the monomer. The first batch contains the catalyst (a mixture of WCl and WOCl, nonylphenol, acetylacetone, additives, and fillers the second batch contains the co-catalyst (a combination of an alkyl aluminum compound and a Lewis base such as ether), antioxidants, and elastomeric fillers (qv) for better moldabihty (50). Mixing two Uquids in a mold results in a rapid polymerization reaction. Its rate is controlled by the ratio between the co-catalyst and the Lewis base. Depending on the catalyst composition, solidification time of the reaction mixture can vary from two seconds to an hour. Similar catalyst systems are used for polymerization of norbomene and for norbomene copolymerization with ethyhdenenorbomene. 

In all of the ethylene polymerization processes, the catalyst is sensitive to feed impurities and is poisoned by most polar compounds. Many of the properties of the polymer are determined by polymerization conditions, but catalyst composition and condition are critical determinants as well. 

In catalytic polymerization the reactivity of the propagation center depends on the catalyst composition. Therefore, the dependence of the molecular structure of the polymer chain mainly on the catalyst composition, and less on the experimental conditions, is characteristic of catalytic polymerization. On the other hand, in polymerization by free-radical or free-ion mechanisms the structure of a polymer is determined by the polymerization conditions (primarily temperature) and does not depend on the type of initiator. 

It is necessary to note the limitation of the approach to the study of the polymerization mechanism, based on a formal comparison of the catalytic activity with the average oxidation degree of transition metal ions in the catalyst. The change of the activity induced by some factor (the catalyst composition, the method of catalyst treatment, etc.) was often assumed to be determined only by the change of the number of active centers. Meanwhile, the activity (A) of the heterogeneous polymerization catalyst depends not only on the surface concentration of the propagation centers (N), but also on the specific activity of one center (propagation rate constant, Kp) and on the effective catalyst surface (Sen) as well ... 

Among one-component polymerization catalysts subhalides of the transition metals are most similar in composition to the traditional Ziegler-Natta catalysts. In this connection, the study of the simplest one-component catalyst of this type (especially TiCl2) is of great importance for the clarification of still disputable problems of the mechanism of polymerization by two-component catalysts. 

Despite the difference in composition of various olefin polymerization catalysts the problems of the mechanism of their action have much in common. The difference between one-component and traditional Ziegler-Natta two-component catalysts seems to exist only at the stage of genesis of the propagation centers, while the mechanism of the formation of a polymer chain on the propagation center formed has many common basic features for all the catalytic systems based on transition metal compounds. 

By using two or more polymerization catalysts simultaneously, polymer chemists can produce copolymers tvith a bimodal composition distribution. This is made possible by the fact that no two catalysts incorporate monomers at exactly the same rate. The net result is that short chain branches may be preferentially incorporated into either the higher or lower molecular weight fractions. Polymer manufacturers can obtain a similar result by operating two polymerization reactors in series. Each reactor produces a resin with a different copolymer distribution, which are combined to form a bimodal product. Copolymers with a bimodal composition distribution provide enhanced toughness when extruded into films. 

The main concept for development of metal-air batteries with new low-cost composite polymeric catalysts is to use catalytic activity of PANI/TEG composition towards the oxygen reduction during the discharge process of battery side by side with non-Faradaic process of anion doping during the charge process (please, see schemes below). 

Certain oxides, particularly clays and synthetic silica-alumina composites, are very active polymerization catalysts. They probably owe their activity to the presence of acidic hydrogen. 

A catalyst composition consisting of magnesium chloride, 1-butanol, titanium tetrachloride, and diisobutylphthalate was prepared by Yang et al. (2) and used in the polymerization of a-olefins. 

TABLE 1. Catalyst Compositions Used in Polymerization of Ethylene and 1-Hexene Described in Table 2... 

The synthesis of polyoctenamer has been commercialized by Huels.150 In contrast with the transformation of cyclooctene to 1,9-decadiene [Eq. (12.31)], homogeneous catalyst compositions, such as WClg + EtAlCl2, are used to promote ring-opening metathesis polymerization of cyclooctene. A polymer of narrow molecular-weight distribution with high trans content (55-85%) called Vestenamer is produced and used as blend component in different rubbers and thermoplastics. 

The catalyst compositions were determined by chemical analysis at the Central Service of Chemical Analysis of the CNRS (Lyon) except for the samples Aj and A2 which were analyzed by Ugicarb Morgon. The analytical method for carbon has been described previously.8 The total amount of carbon was obtained from the combustion of the sample with oxygen. Carbon dioxide was then quantitatively detected by a calibrated thermal conductivity cell. For the polymeric carbon content, the sample was attacked by a hot mixture of nitric and hydrofluoric acids which dissolved every component except for the non-combined carbon. Then, this remaining carbon was transformed into C02 which was analyzed with an electrochemical titration cell. 

Solvent resistant laminates for printed circuits were manufactured by coating of copper foil with a solution of PPO, BPA/DC, bis(4-maleimidophenyl) ether and Zn octoate in toluene the coated foil was laminated with PPO-impregnated glass fabric [47]. Similar result was achieved by the modification of PPO with polyfunctional cyanates or maleimides, liquid polybutadiene and a polymerization catalyst [48], A solvent and heat resistant composition for printed circuits consists of copoly [(2,6-dimethylphenylene)-(2,3,6-trimethylphenylene)]oxide, maleic anhydride grafted poly-1,2-butadiene, bis(4-maleimidophenyl)methane, BPA/DC and toluene. BPA/DC prepolymer may be used instead of the monomer [49]. 

Polymerization activity was obtained with a variety of catalyst compositions. The best stereospecific catalyst was the split pretreated type (357) in which one mole of VC14 was reduced by a stoichiometric amount of an alkyl metal (0.34 mole AlEt3) in heptane at room temperature and heated 16 hours at 90° C. to obtain the purple crystalline VC13-1/3 A1C13. This reduced transition metal component was then treated with two moles of (i-Bu)3Al tetrahydrofuran complex for 20 hours at room temperature to obtain a chocolate-brown catalyst consisting predominantly of divalent vanadium with 0.21 Al/V and 1.4 i-Bu/Al. Polymerizations at 30° C. gave crystalline polymers from methyl, ethyl, isopropyl, isobutyl, tert.-butyl, and neopentyl vinyl ethers. 

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