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  • Analytical Chemistry and Spectroscopy  (16)
  • phase separation  (13)
  • BSSA  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Aggregation Behavior of Alkoxide-Derived Silica in Sol-Gel Process in Presence of Poly(ethylene oxide) (2000)
    Springer
    Journal of sol gel science and technology 17 (2000), S. 7-18 
    Details
    ISSN: 1573-4846
    Keywords: organic-inorganic interaction ; in situ observation of sol-gel reaction ; phase separation ; meso scale structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Growth behavior of silica in an acid catalyzed sol-gel process from silicon alkoxide in the presence of poly(ethylene oxide), PEO, was investigated by in situ small angle X-ray scattering, SAXS, and 29Si NMR measurements. The results of SAXS, that aggregation and gel formation behaviors of silica were affected by the presence of PEO, suggested a strong attractive interaction between silica oligomers and PEO. A possible reaction scheme of silica in the presence of PEO is as follows; (1) PEO and small silica oligomers coexist in the solution without specific interaction just after hydrolysis of the silicon alkoxide. (2) With the progress of condensation, a ramified aggregated complex between PEO and silica oligomers is formed, which is characterized by larger apparent value of radius of gyration and smaller fractal dimension than in the PEO-free system. (3) After gelation, the fractal dimension of scatterers remains to be smaller than that in the PEO-free system, because PEO associated with the silica network inhibits aggregation within the gel networks. Furthermore, PEO inhibits the condensation in the aging and in the drying process, leading to less strongly crosslinked dry gel. A temporal maximum in the time evolution of Rg was observed for the samples separated into two phases with their characteristic domain size being larger than several micrometers. This is considered to be a phenomenon related to increase and divergence of correlation length near and at the critical point.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008753718586
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  • 2
    Electronic Resource
    Electronic Resource
    Membrane Emulsification Using Sol-Gel Derived Macroporous Silica Glass (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 337-341 
    Details
    ISSN: 1573-4846
    Keywords: macroporous silica ; phase separation ; membrane emulsification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A macroporous silica glass membrane with continuous cylindrical pores was prepared by a sol-gel process using phase separation. The applicability of the sol-gel derived macroporous silica to the membrane emulsification process was evaluated in comparison with a conventional SPG (Silasu Porous Glass) membrane. Aqueous colloidal silica in one side of the membrane was emulsified through the pores under an applied pressure to a toluene bath containing surfactant. With the sol-gel and SPG membranes with respective median pore diameters of 0.6 and 1.0 μm, emulsions with almost the same droplet size centered around 3 μm were obtained. The permeation rate of the sol-gel derived membrane was about 1.6 times faster than SPG, which reflected higher pore volume of the former one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008706320776
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation and Chromatographic Application of Macroporous Silicate in a Capillary (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 371-375 
    Details
    ISSN: 1573-4846
    Keywords: phase separation ; silica ; capillary column ; HPLC ; CEC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Continuous macroporous silica gel networks were prepared in a fused silica capillary, and evaluated in reversed-phase liquid chromatography. Under pressure-driven conditions, considerable dependence of column efficiency on the linear velocity of the mobile phase was observed in spite of the small size of the silica skeletons. A major source of band broadening in the pressure-driven mode was found in the A-term of van Deemter equation. The performance of the continuous silica capillary column in the electro-driven mode was much better than that in the pressure-driven mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008770707572
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  • 4
    Electronic Resource
    Electronic Resource
    Macroporous Silicate Films by Dip-Coating (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 553-557 
    Details
    ISSN: 1573-4846
    Keywords: dip coating ; phase separation ; macroporous film ; alkylsiloxane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Macroporous silicate thick films were prepared by the sol-gel dip-coating method accompanied by the phase separation using the composition of methyl-trimethoxysilane (MTMS), nitric acid and dimethylformamide (DMF). The morphology of the film varied to a large extent depending on the time difference between hydrolysis and dipping of the coating solution. The films prepared by early coating had inhomogeneous submicrometer-sized pores on the surface of the film. At increased reaction times, relatively narrow sized internal macropores were observed and their size gradually decreased with the increase of reaction time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008744823927
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  • 5
    Electronic Resource
    Electronic Resource
    Double Pore Silica Gel Monolith Applied to Liquid Chromatography (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 547-552 
    Details
    ISSN: 1573-4846
    Keywords: silicon alkoxide ; phase separation ; double pore structure ; liquid chromatography ; Van Deemter equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica gels retaining double pore structure in the size ranges of micrometer and nanometer have been applied to the rod-shaped monolithic column for liquid chromatography. The macropore structure was designed by controlling the phase separation process induced by the hydrolysis and polycondensation of alkoxysilane, whereas the mesopore structure was tailored by the solvent exchange treatments on wet gels. The size exclusion chromatograms on polystyrene standards exhibited almost similar features for octadecyl-modified rod and conventional packed beads columns. The dependence of plate height on the velocity of mobile phase determined for amylbenzene was by far weaker in the rod column than in the packed beads column, suggesting that additional geometrical factors should be considered in describing the separation mechanism in the rod column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018331101606
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  • 6
    Electronic Resource
    Electronic Resource
    In situ observation of phase separation processes in gelling alkoxy-derived silica system by light scattering method (1994)
    Springer
    Journal of sol gel science and technology 3 (1994), S. 169-188 
    Details
    ISSN: 1573-4846
    Keywords: porous silica gel ; light scattering ; phase separation ; spinodal decomposition ; Cahn's theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The investigation of phase separation processes induced by polymerization reactions of tetramethoxysilane (TMOS) was attempted by a time-resolved light scattering method for TMOS-formamide-water system under the acid-catalyzed condition. Since the early stage of the phase separation exhibits very fast kinetics and weak scattering intensity, the experimental set-up was designed so as to reduce the experimental error and to obtain higher time resolution by using a laser beam expander. For the gels whose morphologies are ‘interconnected structure’ and ‘aggregates of particles,’ it was experimentally found that the wavelength of the concentration fluctuation in the early stage of phase separation was time-independent and its amplitude grew exponentially with time. This suggests that these samples phase-separate by spinodal decomposition mechanism. In the later stages of phase separation, the coarsening process and the following structure-freezing process by gel-network formation were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486556
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  • 7
    Electronic Resource
    Electronic Resource
    Double pore silica gel monolith applied to liquid chromatography (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 547-552 
    Details
    ISSN: 1573-4846
    Keywords: silicon alkoxide ; phase separation ; double pore structure ; liquid chromatography ; Van Deemter equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica gels retaining double pore structure in the size ranges of micrometer and nanometer have been applied to the rod-shaped monolithic column for liquid chromatography. The macropore structure was designed by controlling the phase separation process induced by the hydrolysis and polycondensation of alkoxysilane, whereas the mesopore structure was tailored by the solvent exchange treatments on wet gels. The size exclusion chromatograms on polystyrene standards exhibited almost similar features for octadecyl-modified rod and conventional packed beads columns. The dependence of plate height on the velocity of mobile phase determined for amylbenzene was by far weaker in the rod column than in the packed beads column, suggesting that additional geometrical factors should be considered in describing the separation mechanism in the rod column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436897
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  • 8
    Electronic Resource
    Electronic Resource
    Studies of open tubular micro capillary liquid chromatography. 1. The development of open tubular micro capillary liquid chromatography (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 21-27 
    Details
    ISSN: 0935-6304
    Keywords: Liquid Chromatography ; Capillary, glass ; Preparation of LC-Capillaries ; Investigation of column parameters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Micro capillary columns were successfully applied to liquid chromatography by employing the principles used in micro high performance liquid chromatography. Fundamental investigations on the use of capillary columns in LC were performed for the various column parameters. Good separations of five aromatic hydrocarbons and four kinds of phthalic esters were obtained on a 62 μm I.D. capillary column, coated with SE-30.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240010106
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  • 9
    Electronic Resource
    Electronic Resource
    Micro-HPLC-IP detection system in separation of non-UV absorbing organic compounds (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 210-211 
    Details
    ISSN: 0935-6304
    Keywords: Micro-HPLC ; ICP-AES ; Non-UV absorbing organic compounds ; Size exclusion chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240060412
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  • 10
    Electronic Resource
    Electronic Resource
    Study of open-tubular micro-capillary liquid chromatography (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 371-377 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography, HPLC ; Capillary, glass ; Review on open tubular micro capillary LC ; Technical solutions of the problems in zero dead volume connections ; Capillary LC/MS combination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary columns in gas chromatography, first proposed by Golay [1,2], have become well established [3] which have extremely high column efficiencies and separabilities. Everyone could imagine it to be a great tool if such a kind of high efficiency column could be established in liquid chromatography (LC). Microcapillary liquid chromatography (MCLC) may be one way of achieving high-efficiency in terms of theoretical plates. Few papers were published in this field before 1976 [4-6], but more recently, after 1977 [7-15], this field has become one of topical interest in liquid chromatography. Temporarily there are two microcapillary liquid chromatography, that is: „open-tubular“ [7,8,10-15] and „packed“ [9] MCLC. In this presentation we focus on open-tubular microcapillary liquid chromatography and a review contemporary developments of ours and others.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020621
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