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  • 1
    ISSN: 1573-4846
    Keywords: ORMOSIL ; nafion ; hybrid ; nanostructure ; 29Si NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Perfluorosulfonic Acid (PFSA)]/[Organically-Modified Silicon Oxide (ORMOSIL)] hybrids were formulated via sol-gel reactions of mixtures of tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS) in the nanophase-separated morphology of a PFSA membrane (Nafion®). The molecular structures of the ORMOSIL phases were investigated by 29Si solid state NMR spectroscopy and the spectra compared with those of corresponding bulk ORMOSILs. PFSA-in situ ORMOSIL composition can be tailored by manipulating TEOS/DEDMS source solution composition and quantified by 29Si solid state NMR spectroscopy. Copolymerization of TEOS and DEDMS monomers, rather than block formation, occurs within the PFSA as well as in the bulk. As DEDMS feed concentration increases, ORMOSIL nanostructures are more hydrophobic and more flexible. Dimethylsiloxane rings are dominant in PFSAs in which hydrolysis + condensation of pure DEDMS occurs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1917-1923 
    ISSN: 0887-6266
    Keywords: SAXS ; Nafion® ; ORMOSIL ; sol-gel reaction ; nanocomposite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The small angle X-ray scattering technique was used to probe structural heterogeneity on the scale of nanometers within Nafion®/[silicon oxide], Nafion®/[ORMOSIL], and Nafion®/[dimethylsiloxane] hybrid membranes. The results of this study reinforced the working hypothesis of morphological template action for the in situ growth of silicon oxide, or organically modified silicon oxide phases in perfluorosulfonate ionomers via sol-gel reactions for silicon alkoxide or/and silicon alkylalkoxide precursors. Nanophase separation persists when incorporated silicon oxide particles are postreacted with ethoxytrimethylsilane but postreaction with diethoxydimethylsilane generates co-continuous phases that do not generate ionomer SAXS peaks, presumably due to a more homogeneous Si atom distribution within the ionomer. These hybrids are true nanocomposites, as structural heterogeneity exists on the scale of ∼ 5 nm. The variation of the small angle upturn for these hybrids is explained in terms of long-range inhomogeneities in ionomers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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