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  • hybrid systems  (2)
  • Zr(OPr n )4  (1)
  • 1
    Electronic Resource
    Electronic Resource
    17O NMR Investigation of Chemical Homogeneity in Hybrid Systems (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 553-556 
    Details
    ISSN: 1573-4846
    Keywords: hydrolysis ; condensation ; 17O NMR ; hybrid systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 17O NMR experiments using enriched water were performed to followthe hydrolysis-condensation process of dimethyldiethoxysilanetetraethoxysilane and a 1/1 mixture of dimethyldiethoxysilane andtetraethoxysilane (H2O/OEt = 0.5; pH = 2). The spectrarecorded over several hours time period were simulated to followquantitatively the variations of residual water, hydroxyl groups(Si–17 $$\underline {\text{O}} $$ H) and oxo bridges (Si–17 $$\underline {\text{O}} $$ –Si). Presence of a resonance signal due oxo bridges between di- andtetrafunctional Si units clearly demonstrates that co-condensationreactions occur to a large extent between the two alkoxides, and that thesebonds are stable during the aging period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018335218444
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    17O NMR investigation of chemical homogeneity in hybrid systems (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 553-556 
    Details
    ISSN: 1573-4846
    Keywords: hydrolysis ; condensation ; 17O NMR ; hybrid systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 17O NMR experiments using enriched water were performed to follow the hydrolysis-condensation process of dimethyldiethoxysilane tetraethoxysilane and a 1/1 mixture of dimethyldiethoxysilane and tetraethoxysilane (H2O/OEt=0.5; pH=2). The spectra recorded over several hours time period were simulated to follow quantitatively the variations of residual water, hydroxyl groups (Si−17 OH) and oxo bridges (Si−17 O−Si). Presence of a resonance signal due oxo bridges between di- and tetrafunctional Si units clearly demonstrates that co-condensation reactions occur to a large extent between the two alkoxides, and that these bonds are stable during the aging period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436898
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Design of homogeneous hybrid materials through a careful control of the synthetic procedure (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 567-570 
    Details
    ISSN: 1573-4846
    Keywords: hybrid ; 17O NMR ; 29Si NMR ; hydrolysis ; Zr(OPr n )4
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sols for the synthesis of hybrid organic-inorganic materials have been prepared by mixing zirconiumn-propoxide and methacryloxypropyltrimethoxysilane (MPS). The synthesis was done in two steps: a 15 minute hydrolysis of a MPS:H2O:EtOH 1∶1∶2 mixture and then addition of 0.5 molar equivalent of zirconium alkoxide. All the experimental parameters—hydrolysis ratio, pH, dilution, pre-hydrolysis time—have been optimized through a detailed29Si and17O NMR analysis. Immediately after the addition, 94% of the initial water was consumed for the formation of Si−O−Zr bridges. Cleavage of these bonds, associated with formation of Si−O−SI, and Zr−O−Zr bridges are then observed during the aging time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436900
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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