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Supported zirconocene catalysts on a new support, MgO, were prepared and tested in ethylene polymerization. Three types of impregnation methods were employed to find an optimum supporting method for MgO. The direct impregnation of Cp 2 ZrCl 2 on MgO showed low metal loading and polymerization activity, while the catalyst had a higher metal loading and polymerization activity when MgO was treated with methylaluminoxane (MAO) before supporting. Treatment of MgO with MAO during the supporting step invoked two types of catalytic sites, which was evidenced by the bimodal molecular weight distribution of the polymer products. MgO is considered to have potential as a support for metallocenes.

A silica support for use in olefin polymerization was prepared by the gelation of a stable, colloidal phase of silica sol using a MgCl2 solution as the initiator. The Ziegler-Natta/Metallocene hybrid catalysts prepared using this support exhibited characteristics of both Ziegler-Natta and metallocene catalysts. The polymers produced by the hybrid catalysts showed a bimodal molecular weight distribution pattern and two different melting points, corresponding to products arising from each catalyst. This suggests that the hybrid catalysts acted as individual active species and produced a blend of polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2318–2326, 2000

MgCl2 for use as a catalyst support was prepared by dissolution in methanol and recrystallization in n-decane, followed by vacuum-drying at 2,000 rpm. The prepared support was modified by treatment with alkylaluminum compounds. The activity profile of ethylene over the supported catalysts persisted for periods up to 1 h during the polymerization. The prepared Ziegler–Natta/metallocene hybrid catalysts exhibited the characteristics of both metallocene and Ziegler–Natta catalysts. The polymer produced by the hybrid catalysts gave bimodal peaks in differential scanning calorimetry analysis for ethylene and ethylene/1-hexene polymerization, suggesting that the polymer was composed of two different lamellar structures that were polymerized by each catalyst. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1707–1715, 1998

The MgCl2 supports for an ethylene polymerization catalyst were prepared by the recrystallization method using methanol as a solvent. The effects of different desolvation methods of the recrystallized MgCl2-alcohol adduct on the morphological characteristics of the catalysts were examined. The desolvation method greatly affects the characteristics of the catalyst. The prepared catalysts had different Ti/Mg ratios with respect to both surface content and entire catalyst particles. Considering Ti distribution and activity profiles, not only the polymerization conditions but also the Ti distribution on the catalyst appear to be an important factor which affects the bulk density of the polymers. MgCl2-Trager fur einen Ethylenpolymerisationskatalysator wurden mit Hilfe der Rekristallationsmethode hergestellt, wobei Methanol als Losungsmittel diente. Der Einflus verschiedener Losungsmethoden des rekristallisierten MgCl2-Alkohol-Adduktes auf die morphologischen Charakteristika der Katalysatoren wurde untersucht. Die Losungsmethode beeinflust die Eigenschaften der Katalysatoren betrachtlich. Die dargestellten Katalysatoren wiesen unterschiedliche Ti/Mg-Verhaltnisse auf, sowohl was die Oberflache als auch die gesamten Katalysator-Partikel betrifft. Betrachtet man die Ti-Verteilung und Aktivitatsprofile, dann erweisen sich nicht nur die Polymerisationsbedingungen, sondern auch die Ti-Verteilung auf dem Katalysator als wichtige Faktoren, welche die Dichte der Polymeren beeinflussen.

The MgCl 2 support for a propene polymerization catalyst was prepared by the recrystallization method using ethanol as a solvent and ethyl benzoate as an internal electron donor. The recrystallized MgCl 2 was impregnated with TiCl 4 at various temperatures, and the effect of impregnation temperature on the catalytic activity and isotactic index (I. I.) of polypropene (PP) was investigated. It was found that ethanol and titanium chloride ethoxide (TCE) in the catalyst play an important role in the catalytic activity and I. I. The support treated with TiCl 4 at high temperatures showed good performance but large activity reduction during polymerization. The enhanced performance is mainly due to active Ti species containing small amounts of TCE. The large activity reduction is also mainly due to small amounts of ethanol and TCE, yielding small amounts of atactic sites with low Lewis acidity.

MgCl 2 supports were prepared by the recrystallization method with variation of agitation speed and MgCl 2 concentration of the MgCl 2 -methanol-decane mixture. It was found that the particle size of MgCl 2 and MgCl 2 /TiCl 4 could be controlled by changing the MgCl 2 concentration in a methanol droplet or by changing the size of the methanol droplets. The particle size of the supports and catalysts increased with decreasing speed of agitation and with increasing MgCl 2 content. All the prepared supports and catalysts showed a good spherical morphology

The topical application of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to murine skin produces acute inflammatory and hyperplastic responses that have been associated with the promotion stage of skin carcinogenesis. It has been shown in a previous study that TPA induces the expression of the highly inflammatory cytokine, interleukin (IL) -1 alpha, in the epidermis of SENCAR mice. The goal of this study was to investigate the role of IL-1 alpha in several TPA-induced responses in skin. Topical application of TPA (1 microgram) enhanced the production of immunoreactive IL-1 alpha protein, primarily associated with the suprabasal keratinocytes. IL-1 alpha intradermally injected in the dorsal surface significantly increased (P < 0.001) vascular permeability at low concentrations (1-1000 microU) and increased (P < 0.001) inflammatory cell infiltration and epidermal hyperplasia at higher concentrations (10(3) U). TPA produced fourfold increases in vascular permeability as measured by Evans blue...

Increased expression of interleukin-1 (IL-1) in skin elicits a variety of responses, including inflammation and epidermal hyperplasia, which are also characteristic events elicited by tumor promoters. The goal of this study was to investigate whether various classes of tumor promoters increase expression of IL-1 alpha and whether phorbol ester-induced IL-1 alpha expression can be blocked by antitumor promoters. Northern analysis of mRNA isolated from the dorsal skins of SENCAR mice treated with 1 microgram of 4 beta-12-O-tetradecanoylphorbol-13-acetate (TPA) showed that a single application of TPA produced a significant increase in IL-1 alpha mRNA at 6 h that decreased by 24 h after treatment. Two treatments of TPA at 48-h intervals induced, at 6 h, twice as much IL-1 alpha mRNA as one treatment. Of the other promoters tested, anthralin (22.6 micrograms), mezerein (2 micrograms), calcium ionophore A23187 (120 micrograms), and benzoyl peroxide (20 mg) induced IL-1 alpha mRNA with different kinetics and to different extents. On the other hand, the non-tumor promoting phorbol ester analogue 4 alpha-12-O-tetradecanoylphorbol-13-acetate had little effect on the expression of IL-1 alpha mRNA. The effects of various antitumor promoters on TPA-induced IL-1 alpha mRNA expression were also assessed. Fluocinolone acetonide, mepacrine, and 5,8,11,14-eicosatetraynoic acid were the most effective inhibitors, and each produced about 80% inhibition. Other antitumor promoters such as retinoic acid, N-tosyl-L-phenylalanine chloromethyl ketone, and butylated hydroxytoluene inhibited approximately 35%, 65%, and 50% of TPA-induced IL-1 alpha mRNA expression, respectively. Therefore, this study suggests a possible role of IL-1 alpha in the promotion stage of skin carcinogenesis.

Taking advantage of the fact that H 3 PMo 12 O 40 is highly soluble in some organic solvents, membrane-like H 3 PMo 12 O 40 -blended polysulfone film and H 3 PMo 12 O 40 -blended polyethersulfone film were prepared by using dimethylformamide as a solvent for both. The catalytic activity of H 3 PMo 12 O 40 was remarkably enhanced by blending it with a polymer to form a porous film where H 3 PMo 12 O 40 is uniformly and finely dispersed. The H 3 PMo 12 O 40 -blended polysulfone film showed a higher activity for the oxidation reaction (reaction to acetaldehyde) and a lower activity for the acid catalyzed reaction (reaction to ethylene or diethyl ether) than H 3 PMo 12 O 40 . The H 3 PMo 12 O 40 -blended polyethersulfone film showed higher activities for the oxidation reaction and for the acid catalyzed reaction than H 3 PMo 12 O 40 . The oxidation activity in two film catalysts was about 10 times higher than unsupported H 3 PMo 12 O 40 .

Novel palladium hollow spheres were synthesized using silica spheres as a template, and they were successfully applied as recyclable heterogeneous catalysts for Suzuki cross coupling reactions.