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  • 1
    Electronic Resource
    Electronic Resource
    A novel technique for preparing organophilic silica by water-in-oil microemulsions (1990)
    Springer
    Polymer bulletin 24 (1990), S. 173-179 
    Details
    ISSN: 1436-2449
    Keywords: sol-gel ; silica ; water-in-oil emulsion ; microemulsion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A novel technique to prepare ultramicro spherical silica particles containing vinyl groups on their surfaces is presented. This process is a combination of the sol-gel technique and the water-in-oil microemulsion technique in which hydrolysis and condensation of TEOS [Si(OEt)4] and MPS (trimethoxysilylpropylmethacrylate) take place. Spherical silica particles with a size range from 20 to 70 nm were obtained and the surface concentrations of the double bonds per nm2 were from 4 to 7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297314
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  • 2
    Electronic Resource
    Electronic Resource
    A Covalently Interconnected Phosphazene–Silicate Network: Synthesis and Surface Functionalization (1998)
    Springer
    Journal of inorganic and organometallic polymers and materials 8 (1998), S. 205-214 
    Details
    ISSN: 1572-8870
    Keywords: Phosphazenes ; sol-gel ; urethane ; surface functionalization ; heparin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A sol-gel precursor was prepared by the reaction of poly[bis(2-(2-hydroxyethoxy)ethoxy)phosphazene] (1) with 3-isocyanatopropyltriethoxysilane. It was then sol-gel polymerized to produce a covalently interconnected phosphazene-silicate network with urethane functionalities. Isocyanato groups were introduced on the surface of the network through coupling by allophanate formation between hexamethylene diisocyanate and urethane functionalities on the gel surface. Heparin was immobilized on the surface of the network by reacting hydroxyl or amino groups of heparin with the surface isocyanato groups. The activity of the immobilized heparin was 4.0% that of free heparin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021432026018
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  • 3
    Electronic Resource
    Electronic Resource
    Hybrid materials based on metal oxides and poly(organophosphazenes) (1996)
    Springer
    Journal of inorganic and organometallic polymers and materials 6 (1996), S. 221-236 
    Details
    ISSN: 1572-8870
    Keywords: Hybrid materials ; metal oxides ; polytorganophosphazenes ; sol-gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this paper the sol-gel preparation of hybrid materials made of metal oxide and polytorganophosphazenel components is described. The main problem focused on during this research was to avoid phase separation in order to get homogeneous materials. This problem was pursued looking at the formation of genuine chemical bonds between the exploited polyphosphazenes and the inorganic composite networks. Investigations on the thermal, mechanical, and electroconductive properties of the synthesized, phosphazene-containing composite materials showed that these matrices presented improved mechanical and thermal features with respect to those of the original phosphazene macromolecule, while the ionic conductivities of the prepared molecular hybrids doped with lithium or silver trillate are of the same order of magnitude as those measured for the neat, original phosphazene substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057748
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  • 4
    Electronic Resource
    Electronic Resource
    Partial oxidation of methane over silica supported molybdenum oxide catalysts (1994)
    Springer
    Catalysis letters 30 (1994), S. 159-169 
    Details
    ISSN: 1572-879X
    Keywords: molybdenum oxide ; silica support ; sol-gel ; impregnation ; partial oxidation ; methane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two kinds of MoO3/SiO2 catalysts, MoO3-I and MoO3-S, were prepared by impregnation and sol-gel method, respectively. When MoO3 loading was increased, formation of MoO3 crystals was observed to begin at a MoO3 loading of 8 and 16 wt% with MoO3-I and MoO3-S, respectively. The highest yield of formaldehyde from methane oxidation was attained also at those critical values of MoO3 loading of 8 and 16 wt% over MoO3-I and MoO3-S, respectively. It is suggested that the active species for formaldehyde formation is well dispersed molybdenum oxide clusters on SiO2 support: the optimum dispersion of the clusters affords the highest activity for formaldehyde formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00813682
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of ethylene glycol addition on the properties of Ru/Al2O3 catalyst prepared by sol-gel method (1996)
    Springer
    Catalysis letters 36 (1996), S. 41-49 
    Details
    ISSN: 1572-879X
    Keywords: sol-gel ; Ru/Al2O3 ; ethylene glycol ; characterization ; chelating agent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ru/Al2O3 catalysts were prepared by sol-gel method with an organic additive (ethylene glycol). The effect of the addition of ethylene glycol on the properties of Ru/Al2O3 was characterized by BET, XRD, EXAFS, and TGA/DTA. Ethylene glycol was effective to promote the phase transition of α-Al2O3 even at 800°C calcination with high surface area. This finding is ascribed to the modified structure of aluminum alkoxide by ethylene glycol addition in the solution state. Ethylene glycol is also effective to get small particles of ruthenium after the reduction at 500°C. The EXAFS and UV-Vis spectra of Ru complex revealed that the coordination structure of Ru depended on the additive used. The ethylene glycol sol prefers to form octahedral Ru complex. This Ru complex in alumina matrix is stable up to 200°C and forms small Ru oxide particles even at 300°C calcination. This suggests that ethylene glycol coordinates to the Ru complex as well as to aluminum ion in the initial state, which is important to control the final properties of the Ru/Al2O3 catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807204
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanism of the grafting of organosilanes on mineral surfaces. IV. Phenylderivatives of sepiolite and poly (organosiloxanes) (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 165-176 
    Details
    ISSN: 1435-1536
    Keywords: Phenylsilanes ; sepiolite ; poly(organosiloxanes) ; tetraethyl-orthosilicate (TEOS) ; graftingreactions ; sol-gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Grafting reactions of phenyl groups on silica substrates using as reagents various phenylsilanes with variable distances between the silicon atoms and the aromatic ring by 0, 1, and 2 methylene groups [≡Si−(CH2) n −C6H5] were studied. Two different silicates have been selected as source of silica: sepiolite and tetraethyl-orthosilicate (TEOS). Sulfonic- and nitro-derivatives prepared from these phenyl compounds by electrophilic substitution reactions, have been obtained. The mechanism of these processes has been studied in relation to the number of methylene separating groups belonging to the starting reagents. The characterization of such systems has been achieved by XRD,29Si and13C NMR/MAS, IR, and laser microprobe mass spectrometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652183
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  • 7
    Electronic Resource
    Electronic Resource
    Surface fractal dimension by nitrogen adsorption of microporous sol-gel processed SiO2 ceramics (1997)
    Springer
    Colloid & polymer science 105 (1997), S. 66-71 
    Details
    ISSN: 1435-1536
    Keywords: Surface fractal dimension ; nitrogen adsorption ; microporous ; sol-gel ; ceramics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The stability of acid catalyzed alkoxide-based silica systems containing polyethylene glycol (PEG) of three different molecular weights (M PEG=4600 g/mol,M PEG=10000 g/mol andM PEG=35 000 g/mol) and concentrations (0–9 wt%) have been followed visually. There has been observed a macrophase separation visually which has been explained by the bridging effect between the organic and inorganic polymers. Ceramic materials have been produced from the solgel processed gels. The ceramic materials have been studied by N2 adsorption/desorption isotherms that were indicative of the presence of micropores. The surface fractal dimension by the aid of the N2 adsorption isotherms has been determined on the basis of the proposed Avnir-Jaroniec (AJ) theory. The best linear fitting was chosen to be proportional to the surface fractal dimension. The differences in the surface fractal dimension in the studied materials have been explained in terms of the occurrence of phase separation (microphase separation) between the organic and inorganic polymers on a molecular scale, that made the ceramic materials more compact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01188927
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of alkaline earths and rare earths added to sol-gel alumina on the thermostability and the oxidation activity of the mixed alumina-supported Pt catalysts (1995)
    Springer
    Catalysis letters 32 (1995), S. 139-145 
    Details
    ISSN: 1572-879X
    Keywords: alumina ; carbon monoxide oxidation ; ethylene oxidation ; platinum ; cerium ; sol-gel ; thermostability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Various alumina-based supports were prepared by adding metal elements such as alkaline and rare earths to sol-gel alumina synthesized from aluminium isopropoxide using 2-methylpentane-2,4-diol as a solvent and the influence of the additives on the thermostability of the supports was investigated. It was found that Ba and Sr are the most effective in improving the thermostability of the alumina, La is moderately effective while Zr, Mg and Ca are ineffective. The influence of the additives on the catalytic activities of Pt/CeO x /MO y -Al2O3 (M=Ba, Sr, La) after the calculation at 1273 K was also investigated. Pt/CeO x /BaO-Al2O3 and Pt/ CeO x /La2O3-Al2O3 showed higher catalytic activity than Pt/CeO x /Al2O3, while Pt/CeO x / SrO-Al2O3 showed lower catalytic activity. The activity order was Ba 〉 La = none 〉 Sr in terms of CO and C2H4 oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806109
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  • 9
    Electronic Resource
    Electronic Resource
    Selective hydrogenation of ethyl phenylacetate to 2-phenylethanol: a convenient catalyst preparation method (1994)
    Springer
    Catalysis letters 30 (1994), S. 297-304 
    Details
    ISSN: 1572-879X
    Keywords: hydrogenation ; ruthenium/tin/alumina ; combination ; sol-gel ; impregnation ; ethyl phenylacetate ; 2-phenylethanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A ruthenium-tin-alumina catalyst, prepared by a combination of kneading and impregnation methods, which we have named the combination method, was able to selectively hydrogenate ethyl phenylacetate to 2-phenylethanol; tin oxide was used as a chloride-free tin source. For this combination catalyst, the optimum atomic ratio for Ru: Sn was found to be 1 ∶ 4. X-ray diffraction measurements showed the presence of tin particles. It appeared that the number of the tin particles had a large effect on the hydrogenation of C=O groups. However, the catalyst prepared with ruthenium oxide had a low activity, possibly owing to the ruthenium metal or ruthenium-tin alloy, which was formed and which obstructed the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00813696
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of preparation method of CeOx-Al2O3 on the thermostability and activity of the monolith supported Pt-Rh catalysts for automotive exhaust control (1995)
    Springer
    Catalysis letters 33 (1995), S. 229-235 
    Details
    ISSN: 1572-879X
    Keywords: support ; cerium ; alumina ; sol-gel ; thermostability ; platinum ; three-way catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Various CeOx-Al2O3 powders were prepared and the influence of the method of support preparation on the thermostability of the mixed alumina-supported Pt catalysts and on their oxidation of CO was investigated. It was found that the complexing agent-assisted sol-gel method is effective in improving the thermostability of the mixed alumina-supported Pt catalysts. Monolith Pt-Rh three-way catalysts were prepared using these aluminas and other thermostable alumina including Ba. Activity of the catalysts was also investigated after conducting accelerated thermal engine aging in order to test their durability. Under normal operating conditions of the automobile engine, the activity of the Pt-Rh three-way catalyst using the CeOx-Al2O3 support prepared by the complexing agent-assisted sol-gel method is nearly equal to that of the catalyst using the CeOx impregnated onto BaO-Al2O3 powder prepared by the same sol-gel method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00814227
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