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  • 1
    Electronic Resource
    Electronic Resource
    Hardness Equation for Ormosils (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 627-630 
    Details
    ISSN: 1573-4846
    Keywords: hardness equation ; ormosils ; sol-gel coating ; shear modulus ; silicate glass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hardness of ormosils coating on various kinds of substrates is important, and by considering recent progresses in understanding the hardness of ionic crystals or covalent crystals, new hardness equations for calculating the hardness of glasses or ormosils from chemical compositions were derived. When we applied an indenter to the surface of glass or sol-gel coatings, the surface of indenter is a declined one to the flat surface of glass or coating, thus the applied force should be analyzed by using the shear modulus, S, and Young's modulus, E. This is now well accepted for the analysis of hardness of ionic or covalent bonding inorganic materials. For example, by considering the binding energy and plastic deformation, Gilman showed that Hv of NaCl crystal can be calculated by an equation including elastic stiffness which indicated a good agreement between calculated and observed value. For covalent crystals he reported that the strength of chemical bonds could be correlated with the glide (shear) activation energy for covalent crystals quantitatively. These explanations are basically applied to the hardness of silicate glasses and ormosils. By considering both shear modulus and Young's modulus we have derived equations for calculating the hardness of glasses or ormosils from chemical composition, which includes packing density of atoms and bond energy per unit volume has been taken account. The agreements between calculated and observed hardness values for ormosils were comparatively good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008777731196
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  • 2
    Electronic Resource
    Electronic Resource
    Physical Properties of Sol-Gel Coatings (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 23-29 
    Details
    ISSN: 1573-4846
    Keywords: coatings ; ormosils ; physical properties ; hardness ; abrasion resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One of the most important applications of sol-gel technology is the fabrication of coatings. This is because of the possibility of applying oxide coatings with practically all types of chemical compositions at low ambient temperatures on many substrates of various shapes through the use of liquid solutions. Both oxides and different types of organic-inorganic hybrid coatings have been reported. Both oxides and hybrid coatings are usually amorphous at ambient temperatures but some oxides can be converted to the crystalline phase with heating. Regardless of the intended applications of the coatings their physical properties are always of importance. For instance, an anti-reflective coating for an automobile mirror is of little practical value unless it is fairly scratch-resistant. In this review which covers published information in the past fifteen years, some of the more important results of physical properties of sol-gel derived coatings are discussed firstly for oxides and then for organic-inorganic hybrids. It appears that properties such as the hardness of oxide coatings are inadequate unless the heat-treatment temperatures are in excess of about 400°C. The hybrid coatings, especially when they contain a dispersed phase of a hard solid like colloidal silica, can be processed at temperatures below about 150°C and can improve the performance of organic plastics such as the polycarbonates. There is insufficient scientific understanding of the relationship between physical properties and other interdependent variables such as processing conditions, chemistry and coating thickness. More research in this area will undoubtedly contribute to the availability of better and new coatings via the sol-gel approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008701903087
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  • 3
    Electronic Resource
    Electronic Resource
    Structures and properties of Ormosils (1994)
    Springer
    Journal of sol gel science and technology 2 (1994), S. 81-86 
    Details
    ISSN: 1573-4846
    Keywords: ormosils ; inorganic-organic hybrids ; structure ; silica gels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Organically modified silicates (ORMOSILS) can be conveniently divided into three types. In Type A, the organic such as a dye, is mixed into the sol-gel liquid solution. On gelation, the organic is trapped in the gel. In Type B, a porous oxide gel is first formed and the porosity and pore size controlled by heating. An organic is then impregnated into the pores of the gel. In Type C, the organic is added to the oxide gel liquid solution but unlike Type A, a chemical bond is formed between the oxide and the organic. Types A, B and C can further be mixed. Together, these various types of ORMOSILS offer a very wide spectrum of chemistry, structures and applications. They constitute a new family of exciting materials with new scientific challenges and technical possibilities. A critical review will be presented on these ORMOSILS including structures, properties and applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486217
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanical properties of ormosils (1996)
    Springer
    Journal of sol gel science and technology 7 (1996), S. 151-161 
    Details
    ISSN: 1573-4846
    Keywords: ormosils ; organic-inorganic hybrids ; sol-gel ; modified silica network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Many organically modified silicates (ormosils) can be prepared by the sol-gel method with very different mechanical properties by varying the ratio of polydimethylsiloxane (PDMS) to tetraethoxysilane (TEOS) contents and processing conditions. With a low PDMS concentration, the ormosils are harder, stiffer and stronger than those with higher concentration of PDMS. Even harder ormosils are possible when ultrasonic irradiation is used during synthesis. As the PDMS concentration is increased, the ormosils take on a more flexible nature, and over a critical concentration actually become rubbery. These new rubbery materials can contain as much as 75% inorganic components, and have more stable mechanical properties than commercial rubbers at elevated temperatures. Effects of PDMS addition to the network structure and mechanical properties of the ormosils were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401034
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  • 5
    Electronic Resource
    Electronic Resource
    Nonlinear optical materials by the sol-gel method (1993)
    Springer
    Journal of sol gel science and technology 1 (1993), S. 7-19 
    Details
    ISSN: 1573-4846
    Keywords: nonlinear optics ; inorganic-organic hybrids ; amorphous ferroelectrics ; ormosils ; thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sol-gel method, because of the use of homogeneous liquid solutions and the ability to form gels at room temperature, is uniquely suited for the preparation of many nonlinear optical (NLO) materials, especially films. The preparations of NLO crystalline solids, such as ferroelectrics, oxide glasses, and amorphous ferroelectrics, are described. The preparation of NLO nanocomposites can be made by a number of approaches. These include the mixing of optically active organics into the sol-gel liquid solution, the impregnation of organics into the interconnecting pores of a stabilized oxide gel, and the direct chemical bonding of optically active organics and inorganics to form new hybrid NLO nanocomposites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486425
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  • 6
    Electronic Resource
    Electronic Resource
    Viscosity and structure of Ormosil solutions (1995)
    Springer
    Journal of sol gel science and technology 5 (1995), S. 83-92 
    Details
    ISSN: 1573-4846
    Keywords: organic-inorganic hybrids ; ormosils ; viscosity ; sol-to-gel transition ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract PDMS (polydimethylsiloxane)/TEOS (tetraethoxysilane) system Ormosils (organically modified silicates) can be rubbery or rigid, depending on their chemical composition and processing conditions. In order to determine the relationship between the viscosity and the structure of the Ormosil solutions through the sol-to-gel transition, five kinds of sols (three levels of PDMS, three levels of H2O) were prepared with refluxing. Viscosities were measured using an oscillation method with a cone-and-plate type apparatus. Liquid state 29Si-NMR analyses were made to obtain structural information of the solution. The composition of the starting solution affected the sol-to-gel transition process. The degree of hydrolysis, depending upon the H2O content, controlled the reaction rate and structure of the polymer. Addition of PDMS also contributed to the acceleration of the sol-to-gel transition due to larger PDMS copolymerizing units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00487724
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