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To clarify the stereospecificity of Natta-type catalysts, the temperature dependence of the isotacticity of a polypropylene has been investigated by using H-type or A-type TiCl3 with Al(C2H5)3 or Al(C2H5)2Cl in a study of the kinetic behavior of the polymerization under the conditions T = 30–75°C., P ≈ 1 atm., and [Al]/[Ti] = 1. With the use of Al(C2H5)3 the isotacticity increases with a rise in polymerization temperature, and it approaches that of Al(C2H5)2Cl, which is almost independent of the polymerization temperature. On the other hand, with the use of Al(C2H5)3 the number of the polymerization centers decreases with a rise in temperature, while that with Al(C2H5)2Cl remains unchanged. To explain these results, two kinds of polymerization center have been proposed; one is stable at any temperature and produces a higher-isotacticity polymer, and the other is stable at the higher temperatures and produces a lowerisotacticity polymer. Some solvent effect of the isotacticity has been observed with the use of A-TiCl3. The isotacticity with A-TiCl3 decreases by several per cent when n-heptane is used instead of toluene. This solvent effect has been explained on the basis of the existence of a considerable amount of AlCl3 in A-TiCl3.

The kinetics of the propylene polymerization with TiCl3-AlEt3 has been investigated in the temperature range (30-70°C.), the pressure range of propylene (100-700 mm. Hg), and the concentration range of the catalysts (2 g. TiCl3/liter, [A]/[Ti] = 0.4-3.0). The polymerization rate R increases rapidly with the polymerization time t at first (stage I), which is followed by a gradual decrease to the stationary value Roo, (stage II). The kinetic behavior in stage I in the case when propylene is introduced after the addition of AlEt3 is expressed by and that in the case when propylene is introduced before the addition of AlEt3 is expressed by The kinetic behavior in stage II, which is independent of the above procedure, is expressed by where R∞ is the stationary rate represented by and Ro a constant. The activation energies are E1 = 15, E2 = 17, Et3 = 2-3, E3″ = 12, and EP = 10 kcal./mole, respectively. The heat of adsorption of AlEt3 was obtained as 12 kcal./ mole from the temperature dependence of K. Stage I is explained on the basis of the formation of polymerization centers from Al2Et6 and a propylene monomer on the surface of TiCl3. Stage II is attributed to an irreversible deactivation of the polymerization centers localized on unstable surface sites due mainly to a spontaneous process and partially to a propylene monomer (or polymer) attack.

Propylene polymerization was carried out using the [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3)/Al(iBu)3/Ph3CB(C6F5)4 catalyst system in the presence of cyclohexene. It was found that isospecific polymerization is promoted by adding cyclohexene even at low propylene concentration. It was also indicated that a considerable number of isospecific active species retain the metal-polymer bond. Based on this fact, isotactic poly(propylene)-block-poly(1-hexene) could be obtained.

Inorganic–organic hybrid xerogels bearing indenyl groups on their surfaces have been synthesised by the sol–gel method. The hybrid xerogels were obtained by hydrolysis and polycondensation of bisindenyldiethoxysilane (Ind 2 Si(OEt) 2 ) and tetraethoxysilane, TEOS (Si(OEt) 4 ) under two different conditions. Chemical structure was investigated by ultraviolet spectroscopy (UV–VIS), transmittance (FT-IR) and diffuse-reflectance (DRIFTS) infrared spectroscopy, magic angle spin nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopy (XPS). Xerogel texture and structure were analysed by nitrogen sorption based on the Brunauer–Emmett–Teller (BET) method, X-ray diffraction spectroscopy (XRD), and natural scanning electron microscopy (N-SEM). Under our experimental conditions, in alkaline milieu and 1:3 indenyl/TEOS ratio, a xerogel with higher indenyl content, but nonporous and showing agglomerate patterns was produced (xerogel I). Spherical particles of diameter about 6–8 μm where obtained in the absence of catalyst, using 1:5 indenyl/TEOS ratio, higher temperature and shorter reaction time (xerogel II). Xerogel II was used as support for heterogeneous metallocene catalyst synthesis. The resulting catalyst presented high Zr content (0.68 mmol Zr g cat −1 ) and high catalyst activity (40×10 3 kg PE mol −1 Zr h −1 ) in ethylene polymerisation.

Syntheses of terminally hydroxylated and iodinated isotactic poly(propylene)s were carried out by the reactions of oxygen and iodine with polymer-Al bonds produced in propylene polymerization with [ArN(CH 2 ) 3 -NAr]TiCl 2 (Ar = 2,6-Pr 2 C 6 H 3 ) combined with methylaluminoxane (MAO) as a cocatalyst. The resulting isotactic polymer (ca. 45 wt.-%) was separated from the atactic one by extraction with boiling ether. From 13 C NMR measurements of the isotactic fraction, it was found that the content of the terminally functionalized isotactic poly(propylene) was more than 80 mol-% in all cases.

Inorganic siliceous porous materials with different average pore diameters were applied to the adsorptive separation of methylalumoxane (MAO) used as co-catalyst in α-olefin polymerization. The co-catalytic performance of the separated MAO was investigated by propylene polymerization with rac-ethylene(bisindenyl)zirconium dichloride (rac-Et(Ind)2ZrCl2). The polymerization activity and the stereoregularity of the resulting polymer were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained by the solvent extraction of the produced polymers, it was suggested that the adsorptive separation of MAO by porous materials is helpful in the characterization of MAO, and at least two different species of MAO are present.

Effects of heterogenization parameters on compositional and catalytic properties of Et(Ind) 2 ZrCl 2 supported on silica modified with MAO were evaluated using data on metal loading, catalyst activity in ethylene–propylene copolymerization, and polymer properties. The supported catalysts were prepared according to a 2 3 factorial design for multivariate analysis. The parameters studied were: MAO concentration in impregnation, Et(Ind) 2 ZrCl 2 concentration in grafting, and immobilization temperature for both metallocene and organoaluminum. The grafting solution was monitored by UV–VIS spectroscopy, while the resulting catalyst systems were characterized by inductively-coupled plasma-optical emission spectroscopy (ICP-OES), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). At high statistical significance, both MAO and Et(Ind) 2 ZrCl 2 concentrations during preparation affected the determination of the final Al/Zr ratio on silica. The catalyst systems were tested in ethylene–propylene copolymerizations using external MAO as cocatalyst. Relationships were observed between (i) catalyst activity and the binding energy of Zr 3d 5/2 electrons and (ii) Al/Zr ratio on silica and the average ethylene incorporation. The polymer samples presented narrow molecular weight distribution, but according to differential scanning calorimetry (DSC), and cross-fractionation chromatography (CFC) data, catalyst systems with given Al/Zr ratios might yield different crystallites, suggesting a plural distribution of chemical composition.

Propylene polymerization was carried out with [Ar (*) N(CH 2 ) 3 NAr (*) ]TiCl 2 (Ar = 2,6- i Pr 2 C 6 H 3 and Ar* = 2,6-Me 2 C 6 H 3 ) and [ArNCH 2 PhCH 2 NAr] TiCl 2 (Ar = 2,6- i Pr 2 C 6 H 3 ) complexes as catalysts. MAO and various combinations of trialkylaluminium and boron compounds as cocatalysts were employed to investigate the stereospecificity of the present catalysts system. Isotactic PP was obtained using [ArN(CH 2 ) 3 NAr]TiCl 2 and [ArNCH 2 Ph-CH 2 NAr]TiCl 2 (Ar = 2,6-iPr 2 C 6 H 3 ) complexes. It was newly found that even the polymerization with MAO as cocatalyst affords isotactic PP. It was confirmed that isotactic PP could be produced when R in the employed trialkylaluminium (AlR 3) became bulkier than an isobutyl group. The steric hindrance around the active metal center caused by the substituents in the ligand orbulky group in the bridge of the catalyst was found to play an important role for the sterospecificity of the present catalyst system.

Four supported metallocenes prepared by the sol‐gel method were tested by ethylene homopolymerization and in ethylene/1-hexene copolymerization. The effects of Al/Zr ratio, polymerization temperature and cocatalysts were evaluated. Catalyst A2, produced by TEA and MAO treatments showed the highest activity (180 £ 10 3 kg PE/mol Zr h 21 ) among the tested systems at Al/Zra 1000. A2 showed thermal stability on polymerization performed at a temperature as high as 1208C. All the systems exhibited activity in the presence of common alkylaluminum (TMA, TEA, TIBA). Comonomer effect was observed in the copolymerization of ethylene with 1-hexene, where the comonomer incorporation is about 7 mol%. SAXS measurements of the employed xerogel suggested a weakly branched polymeric texture. Metal content in the resulting polymers showed extremely low levels of Zr. q 2001 Elsevier Science Ltd. All rights reserved.

Inorganic silicous porous materials such as MFI type zeolite, mesoporous silica MCM-41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in α-olefin polymerizations. The separated MAOs combined with rac-ethylene-(bisindenyl)zirconium dichloride (rac-Et(Ind) 2 ZrCl 2 ) were introduced to propylene polymerization, and their influences on the polymerization activity and stereoregularity of the resulting polymers were investigated. The polymerzation activity and isotactic [mmmm] pentad of the produced propylene were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained from solvent extraction of the produced polymers, it was suggested that there are at least two kinds of active species with different stereospecificity in the rac-Et(Ind) 3 ZrCl 2 /MAO catalyst system.

Four metallocene catalysts were prepared using two indenyl-containing aerogels as supports, treated under different conditions (triethylaluminum (TEA), methylaluminoxane (MAO) and butyllithium). The catalysts were characterized by complementary spectroscopic techniques: ultraviolet–visible spectroscopy (UV–Vis), X-ray photoelectronic spectroscopy (XPS), matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The highest metal content (1.32 mmol Zr/g-cat.) was achieved in the case of xerogel treated with TEA prior to metallocene synthesis. After MAO leaching, such content is reduced to 0.82 mmol-Zr/g-cat., exhibiting the highest activity in ethylene polymerization among the four developed catalysts. A relationship between catalyst activity and binding energy of Zr 3d 5/2 core level could be evidenced. The most active catalyst system showed a better Zr distribution, being the catalyst grain covered by aluminum cocatalyst. Depth profile monitoring by XPS measurements showed that, in fact, MAO leaches the zirconocene low binding energy species, being deposited in the uttermost surface of the grains.

Highly isolactic poly(propylene) with T m = 69.5°C and [mmmm] > 99% in hich selectivity (I.IW 99.9% was prepared with the catalyst system Cr(aca) 3 /MgCl 2 -DEAC. 13 C NMR analysis of low molecular weight isotatic polypropylene indicate that the propylene monomer was inserted in the polymer-metal bond via 1,2-addition selectively. Polymerization activities and isospecificity of the catalyst markedly increase with decreasing Cr content in the catalyst, In ethylene homopolymerization, the Cr(acac) 3 /MgCl 2 catalyst showed almost constant activity for 3 h and produced high molecular weight polyethylene with narrow molar mass distribution.

Copolymerizations of ethylene and o-olefins (4-methyl-1-pentene, 1-hevene, 1-decene and 1-hexadecene) were carried out with Et(1-Ind)(9-Flu)ZrCl 2 -MAO as the catalyst system. The degree of alternation in the resulting copolymers is higher than 92.1% for all the copolymers and close to 100% for ethylene-1-decene copolymer, Copolymerization behaviours focusing on the misinsertions during the polymerizations are investigated in detail from dyad and triad distributions estimated by 13 C NMR analysis of copolymers. A reactivity ratio, r E B , was obtained for ethylene-1-bexene copolymers using a simplified two sites alternating mechanics and found to be 8.7, which is the same order of that reported in ethylene-propene copolymerizations with Me 2 C(3-RCp)(Flu)-ZrCl 2 -MAO as the catalyst system.

MgCl 2 -supported Cr(aca) 3 catalyst combined with diethylaluminium chloride (DEAC) was applied to the copolymerization of ethylene and propylene in the presence and absence of ethylbenzoate (EB) as external donor. The productivity was strongly dependent on the isospecificity and Cr content of the catalyst. 13 C NMR and GPC analyses of the resulting copolymers showed that random copolymers were synthesised with narrow molar mass distribution and the enantioselectivity of the catalyst was retained even in the copolymerization

Bis(cyclopentadienyl) zirconocene dimethyl (Cp 2 ZrMe 2 ) combined with triphenylcabenium tetrakis(pentafluorophenyl) borate ([Ph 3 C][B(C 6 F 5 ) 4 ]) was brought into contact with a suspension of 2% cross-linked poly(4-vinylpyridine) to give a new type of poilymer-supported cationic zirconocene catalyst. The resulting polymer-supported catalyst system combined with Al(i-Bu 3 ) showed markedly high activity for ethylene polymerization in even a non-polar solvent like hexane at 25-60°C and [A1]/[Zr] molar ratio 40-200. By the analysis of ZR content of the hexane solutionn, it xas found that no Zr was detected in the solution, i.e., no leaching of the cataionic catalyst into the hexane medium. The catalytic activity was found to increase with an increase of polymerization temperature and showed the highest at [A1]/[Zr] = 100. The molecular weight, crystalline melting temperature, crystallinity, and bulk density of polyethylene formed were higher than those of the polymer obtained from the homogeneouse system.

Polymer supported borate complexes were synthesized using poly(styrene-co-4-bromostyrene) and polystyrene-beads as carriers. These complexes were reacted with rac-Et[Ind]2ZrCl2 (Ind=indenyl) or Ph2C[(Cp)Flu]ZrCl2 (Cp=cyclopentadienyl, Flu=Fluorenyl) in toluene, at a molar ratio of [Zr]/[B]=1, to obtain polymer supported catalysts. Polymerizations of ethylene and propylene were conducted over them in the presence of Al(i-C4H9)3 as an activator. When poly(styrene-co-4-bromostyrene) was used as the carrier, the resulting soluble catalyst showed high activity comparable to those of the corresponding homogeneous catalysts for ethylene polymerization. For propylene polymerization, however, those catalysts showed low-activity. Even though the insoluble catalysts prepared with polystyrene-beads as carrier displayed far less activities for both ethylene and propylene polymerizations, it was found that the shape of polyethylene obtained at 40°C is a replica of the carrier particle.

Cis-specific living polymerizations of 1,3-butadiene (BD) catalyzed by the catalyst system composed of C5H4RTiCl3 (4a, R = H; 4b, R = n-butyl; 4c, R = isopropyl; 4d, R = tert-butyl; 4e, R = trimethylsilyl) with methylaluminoxane (MAO) to give polyBDs with narrow molar mass distribution and high cis content are described. Polybutadienes (polyBDs) prepared by the catalyst at −25 °C are monodispersed (Mw/Mn = 1.04−1.05) in all cases. From the comparison with propagation rate constants (kp), the order of polymerization activity was as follows: 4d > 4e > 4c > 4b = 4a. The microstructures of polyBDs were all dominated by the cis configuration. The complex 4d having bulky tert-butyl group showed higher cis specicficity. Both kps and cis specificity in the polymerization of BD were strongly affected by the substituents introduced on the cyclopentadienyl ring.

The polymerization of 2-butene and its copolymerization with ethylene have been investigated using four kinds of dichlorobis(β-diketonato)titanium complexes, [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3) and typical metallocene catalysts. The obtained copolymers display lower melting points than those produced of homopolyethylene under the same polymerization conditions. 13C NMR analysis indicates that 9.3 mol-% of 2-butene units were incorporated into the polymer chains with Ti(BFA)2Cl2-MAO as the catalyst system. With the trans-2-butene a higher copolymerization rate was observed than with cis-2-butene. A highly regioselective catalyst system for propene polymerization, [ArN(CH2)3NAr]TiCl2 complex using a mixture of triisobutylaluminium and Ph3CB(C6F5)4 as cocatalyst, was found to copolymerize a mixture of 1-butene and trans-2-butene with ethylene up to 3.1 mol-%. Monomer isomerization-polymerization proceeds with typical metallocene catalysts to produce copolymers consisting of ethylene and 1-butene.

The polymerization of 4-methylstyrene with the (trimethyl)pentamethylcyclopentadienyltitanium (Cp*TiMe3)/tris(pentafluorophenyl)borane (B(C6F5)3)/trioctylaluminium (AlOct3) catalytic system at –20°C was carried out. The number-average molecular weight (Mn) of the polymers increased linearly with increasing monomer conversion. The propagating chain ends were successfully reacted with tert-butyl isocyanate, and the Mn of the polymer determined by 1H NMR was in good agreement with the Mn determined by GPC measurement. It is concluded that this catalytic system promoted the syndiospecific living polymerization of 4-methylstyrene.

Effects of acid treatment variables on the realumination efficiency for realumination of dealuminated HZSM-5 zeolite (reinsertion of non-framework aluminums into the zeolite framework) were investigated using 27Al MAS NMR and nitrogen adsorption. Among various mineral acids employed, HCl solution was the most effective for the realumination. The realumination efficiency was also studied, evaluating the change in the cracking activity of cumene. The cumene cracking activity of the realuminated HZSM-5 zeolite was comparable to that of the parent zeolite, whose framework SiO2/Al2O3 ratio was the same as that of the realuminated zeolite. From the results obtained, it was found that no structural degradation of HZSM-5 zeolite crystals takes place during the acid treatment and that som of the non-framework aluminums in dealuminated HZSM-5 zeolites are reinserted into the framework.

The carbonylation of formaldehyde with carbon monoxide was carried out over two kinds of cation-exchange resins as solid acid catalysts. Effects of reaction conditions on the catalytic performance were studied. From 1H NMR, 13C NMR, IR, and GC-MS analyses of the products obtained, it was found that 1,3-dioxolan-4-one (1,3-DOX-4) is selectively produced over the cation-exchange resins. The carbonylation of formaldehyde with carbon monoxide over the cation-exchange resins proceeds under milder reaction conditions, as compared with HZSM-5 zeolite.

The polymeric [Ind 2 Si(C 6 H 4 )] n and [Ind 2 Si(C 6 H 4 ) 2 ] m compounds (Ind = indenyl) were synthesized via the condensation reaction of bisindenyldichlorosilane and p-dilithiobenzene or p-dilithiobiphenyl, and the supported-type zirconocene catalysts were prepared by reacting them with zirconium tetrachloride. The content of zirconium in the catalysts is much higher than that in the metallocene catalysts supported by inorganic compounds. Polymerizations of ethene and propene were conducted with them using methylaluminoxane (MAO) or ordinary alkylaluminiums as cocatalysts and toluene as the solvent. The catalysts combined with MAO display very high activities especially for the ethene polymerization. From the polymerization at high temperatures, it was found that the active species are markedly stabilized, probably due to the rigid backbones of the carriers. The activity of the catalysts activated with ordinary alkylaluminiums is far less as compared with those activated with MAO.

Copolymerizations of ethylene with endo-dicyclopentadiene (DCP) were performed by using Cp2ZrCl2 (Cp = Cyclopentadienyl), Et(Ind)2ZrCl2 (Ind = Indenyl), and Ph2C(Cp)(Flu)ZrCl2 (Flu = Fluorenyl) combined with MAO as cocatalyst. Among these three metallocenes, Et(Ind)2ZrCl2 showed the highest catalyst performance for the copolymerization. From 1H-NMR analysis, it was found that DCP was copolymerized through enchainment of norbornene rings. The copolymer was then epoxidated by reacting with m-chloroperbenzoic acid. 13C-NMR spectrum of the resulting copolymer indicated the quantitative conversion of olefinic to epoxy groups. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 103–108, 1999

Dynamic mechanical behavior of a series of partially hydrogenated polystyrenes with various degrees of hydrogenation has been investigated. The primary relaxation process ascribed to glass transition shifts to higher temperatures and broadens with increasing degree of hydrogenation. There exist two secondary dispersions in a temperature range from 110 to 250 K. The frequency dependence of these relaxation processes and the molecular dynamics simulation suggest that the secondary relaxations are associated with the chair-chair flipping and oscillatory rotation of the cyclohexyl group.

Syndiotactic polystyrenes (sPS) with different molecular weights were hydrogenated over the Ni/SiO2 and Pd-BaSO4 catalysts. Although the Ni catalyst yielded a completely hydrogenated sPS with a lower molecular weight, the hydrogenation of sPS with a high molecular weight was incomplete. On the other hand, the Pd catalyst was capable of hydrogenating sPS with a high molecular weight. However, the hydrogenated sPS (HsPS) was found to contained a small quantity of isolated styrene units. From a detailed analysis of the HsPS by differential scanning calorimetry (d.s.c.) and X-ray, it was revealed that this HsPS has a potential as a crystalline material with an excellent heat-resistance.

To get more information concerning zeolite synthesis in the presence of 1-butanol (n-BuOH), influences of the alkali metal cation and the synthesis conditions on the zeolite synthesis were investigated. It was found that highly crystalline TON (Theta-1), MER (Merlinoite) and LTL (L) type zeolites were synthesized when KOH was employed as an alkali source, whereas MFI (ZSM-5) and MOR (Mordenite)type zeolites for NaOH. Characterization of zeolites obtained was conducted using X-ray diffraction, scanning electron microscopy, FT-IR, thermal analysis, 13C and 27Al MAS NMR. From the results of FT-IR and 13C CP MAS NMR measurements of as-made zeolites, it was concluded that n-BuOH molecules were occluded in the zeolitic pores of TON and MFI type zeolites, while no n-BuOH molecules for MOR, MER and LTL type zeolites.

The mechanism of polyethylene particle growth was investigated using poly(styrene-co-divinylbenzene) (PS beads) supported rac-Ph2Si(Ind)2ZrCl2 catalyst. From the analysis of the resulting polyethylene particles by SEM (scanning electron microscopy) and EPMA (electron probe microanalysis), it was found that the active species are located on the surface layer of catalyst particles and that the catalytic species are uniformly distributed throughout the polymer particles, whereas the cores of PS beads, which lack a potential active species, were not disintegrated during polymerization. These results suggest that the PS beads supported catalyst also follows the fragmentation and replication process as frequently observed with the MgCl2 supported Ziegler–Natta catalysts.

Both the rac- and meso-dinuclear ansa-zirconocene catalysts (μ-C12H8{[SiPh(Ind)2]ZrCl2}2) were prepared by a coupling reaction between 2 equiv of diindenylphenylchlorosilane (rac- and meso-isomers) and 1 equiv of p-dilithiobiphenyl in diethyl ether at −80°C, followed by a successive reaction with ZrCl4 · 2THF in THF at −78°C. Polymerizations of ethene and propene were conducted in a 1 dm3 high-pressure glass reactor equipped with a mechanical stirrer at 60, 80, 100, 120, and 150°C using methylalumoxane (MAO) as cocatalyst and toluene or decahydronaphthalene as the solvent. Copolymerization of ethene and 1-octene was also checked in brief. For ethene polymerization, the meso-catalyst was found to be more active, which displayed an extremely high activity to give linear polyethene with a high molecular weight and a narrow molar mass distribution (MMD). The apparent activity increased monotonously with rising polymerization temperature from 60°C up to 150°C, indicating that the active species are stable even at a high temperature. On the other hand, both the rac- and meso-catalysts showed very poor activities for propene polymerization. However, copolymerization of ethene and 1-octene proceeded at a high speed. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2269–2274, 1998

Four non-bridged dimethylzirconocene complexes. i.e., bis(η 5 -cyclopentadienyl )dimethylzirconium (1), (η 5 -cyclopentadienyl) (η-fluorenyl)dimethylzirconium (2), bis(η 3 -indenyl)dimethylzirconium (3) and (η 5 -cyclopentadienyl)(η 5 -pentamethylcyclopentadienyl)dimethylzirconium (4) were synthesized and used as a catalyst for the methyl methacrylate polymerization combined with triphenylmethyl tetrakis(pentafluorophenyl)borate in the presence of ZnEt 2 or Al(i-Bu) 3 . The catalyst activity strongly depends on the zirconocene compound and decreases in the order 2 > 1 >> 3 4. The polymerization proceeds in a living manner when 1 and 2 are used combined with ZnEt 2 . On the other hand, stereoregularities of the resulting polymers are independent of the zirconocene compound, and syndiotactic-rich polymers are formed by a chain-end controlled mechanism.

Various MgCl 2 -supported Ti(4,4,4-trifluoro- 1-phenyl-1,3-butanedionato) 2 C catalysts with different Ti contents (0.017∼0.002 mmol/g) were synthesized and applied to propene polymerization using triethylaluminium and di-i-propyldimethoxysilane (DIPDMS) as the cocatalyst and external donor, respectively. When polymerization was conducted in the absence of DIPDMS, neither the activity nor the isospecificity of catalyst were dependent upon the Ti content. However, the effect of DIPDMS on the catalyst performance was found to be markedly dependent upon the Ti content, i.e., the addition of DIPDMS to the catalyst with low Ti content caused a prominent increase in the activity for isotactic polymerization. As a result, the present catalyst with low Ti content gave a highly isotactic polypropene with T m = 169.3°C and [mmmm] > 99% in high selectivity (1.1. = 97.7%).

Poly(styrene-co-divinylbenzene) beads supported rac-Ph 2 Si(Ind) 2 ZrCl 2 was prepared and tested as a catalyst for ethene polymerization using methylaluminoxane (MAO) as a cocatalyst. At a polymerization temperature below 100°C, the catalyst showed pretty high activity to give polyethene beads replicating the shape of the carrier. With increasing polymerization temperature up to 150°C, the catalyst activity increased drastically but the spherical shape of polyethene disappeared due to the melting. From the plots of apparent activity against polymerization temperature, it was suggested that the polymerization below 100°C is more or less controlled by monomer diffusion through the crystalline polyethene films.

The V(acac)3 (acac = acetylacetonato)/AlEt2Cl catalyst is known to promote the living polymerization of propylene at low temperature. In the present study, the catalyst was modified by contacting with α,ω-unconjugated diene compounds, and the resulting catalyst was applied to propylene polymerization. The polymer produced shows a bimodal molar mass distribution, where the molecular weight of the higher molecular weight portion is twice that of the lower molecular weight portion. By using the CO quenching technique, it was found that the polymer with the higher molecular weight has a telechelic structure.

Poly(siloxane)s with bisindenyl, bisfluorenyl, bis(1,2,3,4-tetramethylcyclo-pentadienyl), bis(2,4,7-trimethylindenyl) and monoindenylmethyl side groups were synthesized by condensation of the corresponding dichlorosilanes and water. For reference, diphenylsilanediol or hydroquinone was also employed in place of water. A series of poly(siloxane)-supported zirconocene catalysts were then prepared from these precursors and applied to ethene and propene polymerizations as well as to the copolymerization of ethene with 1-octene in the presence of methylalumoxane. The polymerization activity of the new supported metallocenes depends drastically upon the substituents in the siloxane backbone. The zirconocene catalysts supported on poly bisindenylsiloxane) and poly(bisfluorenylsiloxane) give the highest activities for ethene and propene polymerizations, respectively. The weight-average molecular weights of the polymers are also markedly dependent upon the substituents. On the other hand, the molecular mass distributions ( MMD ) are generally not so sharp, suggesting that the active species formed in these supported catalysts are not uniform.

A novel dinuclear ansa-zirconocene catalyst ( μ -C 12 H 8 {[SiPh(Ind) 2 ]ZrCl 2 } 2 ) ( I ) was prepared by a Wurtz coupling reaction between two equivalent of bisindenylphenylchlorosilane and one equivalent of 4,4′-dibromobiphenyl in THF at reflux temperature for 12 h, followed by a successive reaction with ZrCl 4 ·2THF in THF at −78°C. Polymerization of ethene was conducted in a 300 cm 3 glass reactor equipped with a stirrer at 40, 60, 80 and 100°C using MAO or Ph 3 C[B(C 6 F 5 ) 4 ] as cocatalyst and toluene as the solvent. The catalyst ( I ) gave linear polyethene with a broader molecular mass distribution (MMD) in a much higher yield as compared to the corresponding mononuclear catalyst derived from [Ph 2 Si(Ind) 2 ]ZrCl 2 ( II ). The apparent activity increased monotonously from 40°C up to 100°C. The replacement of MAO with Ph 3 C[B(C 6 F 5 ) 4 ] gave polyethene with a higher molecular weight.

Several kinds of dichlorobis(β-diketonato)titanium complexes, i.e., Ti (acetylacetonato) 2 C1 2 , Ti(1-benzoy1acetonato)2C12, Ti(2,2,6,6-tetramethyl-3,5-heptanedionato) 2 C1 2 and Ti(4,4,4-trifluoro-1-phenyl-1,3-butanedionato) 2 C1 2 ,were synthesized and the corresponding MgCl 2 -supported catalysts were prepared by impregnation method. The test of them for propene polymerization revealed that those MgC1 2 -supported catalysts could be activated not only by methylaluminoxane (MAO) but also by ordinary alkylaluminums as well. The effect of typical Lewis bases on the catalyst performance was investigated in some detail, which indicated that organic silanes are most effective for the improvement of isospecificity of those catalysts.

The effect of framework aluminum on the dissolution behavior of ZSM-5 zeolite crystal was systematically studied using an interferometric technique. We succeeded in the three-dimensional measurement of the dissolution rates of aluminum-containing ZSM-5 zeolite crystal, namely the (010) face of ZSM-5 zeolite crystal as well as the (100) and (001) faces. The dissolution rate was dependent strongly upon the amount of framework aluminum of the zeolite crystal and the concentration of NaOH aqueous solution used. It was also found that the aluminum-containing ZSM-5 zeolite crystal is convex and that the inclination of the (010) face at the edge of the ZSM-5 zeolite crystal is steeper than that of silicalite crystal.

The copolymerization of ethylene and a poly(propylene) macromonomer, the number-average polymerization degree (P n ) of which was about 11, was conducted with (tert-butanamide)dimethyl(tetramethyl-η 5 -cyclopentadienyl)silanetitanium dichloride (CGC-Ti) combined with methylaluminoxane. The rate of ethylene consumption is increased by adding the macromonomer when copolymerization was carried out at 40°C, whereas such rate enhancement could not be observed at 90°C. It was found that the increase of ethylene polymerization rate is accompanied by the incorporation of the macromonomer. Based on differential scanning calorimetry (DSC) and 13 C NMR measurements of the produced polymers, it was proved that the poly(propylene) macromonomer was copolymerized with the present CGC-Ti catalyst and the P n value of the macromonomer incorporated in the copolymer does not influence the conversion of the macromonomer.

Copolymerizations of ethylene and α-olefins with homogeneous metallocene catalysts generally give the corresponding random copolymers with narrow molecular mass distributions. In this study, we have conducted the copolymerization of ethylene and 1-octene with the meso-Me2Si(2-Me-1-Ind)2ZrCl2-methylaluminoxane (MAO) catalyst system, and analyzed the microstructure of the resulting copolymers in detail. The content of the alternating [EO] sequence increases markedly with an increase in the feed ratio of 1-octene to ethylene, reaching over 95% under appropriate copolymerization conditions. We have thus succeeded in preparing the first sample of alternating olefin copolymers.

A supported version of zirconocene catalysts on siloxane copolymers having 1,2,3,4-tetramethylcyclopentadienyl (Cp)-fluorenyl (Flu) (I) or cyclopentadienyl (Cp)-fluorenyl (II) groups as substituents was prepared and applied to propene polymerization using methylalumoxane (MAO) or [Ph 3 C][B(C 6 F 5 ) 4 ] as cocatalyst. Catalyst (I), which was soluble in toluene, exhibited very low activity, whereas catalyst (II), which was composed of a toluene soluble (Cat-A) and an insoluble fraction (Cat-B), displayed a fairly high activity. Both catalysts (A and B) give a mixture of syndiotactic, atactic and a small quantity of isotactic polypropene, with a fraction of syndiotactic pentads ranging from about 50-75%. In contrast, the corresponding non-supported catalyst gives almost completely atactic polypropene.

Polymerization of propene was conducted at 40°C under reduced pressure (0.35-1.0 atm) using the C 1 -symmetric threo- i Pr(3- t BuCp)(3- t BuInd)ZrCl 2 /MAO and TiCl 4 /MgCl 2 /Al( t Bu) 3 catalyst systems and the effect of propene pressure on the microstructure of the resulting isotactic polypropene was investigated. In the case of C 1 -symmetric metallocene, the [mmmm]-pentad fraction decreased moderately with decreasing propene pressure, but the magnitude of decrease was much smaller than those reported by Busico et al. using typical C 2 -symmetric metallocenes. Whereas, the [mmmm]-pentad fraction of isotactic polypropene obtained with the conventional Ziegler-Natta catalyst did not change so much in the pressure range. Thus, epimerization of the growing polymer chain was found to be drastically dependent upon the catalyst system.

To clarify the influence of the crystallinity (structure defect) of zeolites on dealumination behavior, HZSM-5 zeolites synthesized using 1-BuOH and TPABr were dealuminated under a hydrothermal atmosphere. It was found that the dealumination rate of the HZSM-5 zeolite has apparently a third-order dependence upon the number of framework aluminums in the zeolite structure and that, in the case of the lower water vapor pressure, below 10 kPa the dealumination rate of the HZSM-5 zeolite synthesized using 1-BuOH is smaller than that of the zeolite synthesized using TPABr. Taking into account the fact that the peak intensity at ca 3,740 cm −1 assigned to silanol groups is very weak in the spectrum of the HZSM-5 zeolite from 1-BuOH as compared with that from TPABr, this seems to indicate that the dealumination rate strongly depends upon the crystallinity of zeolite, namely, the structure defect. It was also found that the dealumination rates of the HZSM-5 zeolites synthesized using 1-BuOH and TPABr have approximately a second-order and a 1.5-order dependence on water vapor pressure, respectively. Based on the results obtained, a plausible mechanism of the dealumination of HZSM-5 zeolite by hydrothermal treatment was discussed.

The MgCl 2 supported half titanocenes and Ti(4,4,4-trifluoro-1-phenyl-1,3-butanedionato) 2 Cl 2 catalysts were synthesized and applied to propene polymerization. Without supporting on MgCl 2 , those complexes displayed almost no activity even using methylaluminoxane (MAO) as cocatalyst. When supported on MgCl 2 , on the other hand, the resulting catalysts could be activated by ordinary alkylaluminums to yield polypropene in fairly high yields. The catalyst isospecificity was markedly improved by the addition of a suitable Lewis base.

Copolymers of styrene and a styrene derivative having a C s symmetrical ligand moiety were synthesized and used as the carrier for the synthesis of supported-type zirconocene catalysts. Propene polymerization was conducted using the resulting catalyst together with methylalumoxane (MAO), which gave syndiotactic polypropene. The productivity of the polymer-supported catalyst (4010 kg PP (mol Zr) −1 for 24 h) was, however, very low compared to that of the corresponding homogeneous catalyst (9130 kg PP (mol Zr) −1 for 20 min).