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Jitianu, A., Cadars, S., Zhang, F., Rodriguez, G., Picard, Q., Aparicio, M., Mosa, J. & Klein, L. C. (2017) Si-29 NMR and SAXS investigation of the hybrid organic-inorganic glasses obtained by consolidation of the melting gels. Dalton Trans. 46 3729–3741. 
Added by: Richard Baschera (2017-04-28 13:01:15)   Last edited by: Richard Baschera (2017-04-28 13:08:44)
Type de référence: Article
DOI: 10.1039/c6dt04394a
Numéro d'identification (ISBN etc.): 1477-9226
Clé BibTeX: Jitianu2017
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Catégories: INTERNATIONAL, ST2E
Mots-clés: advanced photon source, angle-spinning nmr, h-1 mas nmr, modified mesoporous silica, oxycarbide glasses, polysiloxane networks, sioc glasses, solid-state NMR, structural-characterization, x-ray-scattering
Créateurs: Aparicio, Cadars, Jitianu, Klein, Mosa, Picard, Rodriguez, Zhang
Collection: Dalton Trans.
Consultations : 5/408
Indice de consultation : 1%
Indice de popularité : 0.25%
Résumé     
This study is focused on structural characterization of hybrid glasses obtained by consolidation of melting gels. The melting gels were prepared in molar ratios of methyltriethoxysilane (MTES) and dimethyl-diethoxysilane (DMDES) of 75% MTES-25% DMDES and 65% MTES-35% DMDES. Following consolidation, the hybrid glasses were characterized using Raman, Si-29 and C-13 Nuclear Magnetic Resonance (NMR) spectroscopies, synchrotron Small Angle X-Ray Scattering (SAXS) and scanning electron microscopy (SEM). Raman spectroscopy revealed the presence of Si-C bonds in the hybrid glasses and 8-membered ring structures in the Si-O-Si network. Qualitative NMR spectroscopy identified the main molecular species, while quantitative NMR data showed that the ratio of trimers (T) to dimers (D) varied between 4.6 and 3.8. Two-dimensional Si-29 NMR data were used to identify two distinct types of T-3 environments. SAXS data showed that the glasses are homogeneous across the nm to micrometer length scales. The scattering cross section was one thousand times lower than what is expected when phase separation occurs. The SEM images show a uniform surface without defects, in agreement with the SAXS results, which further supports that the hybrid glasses are nonporous.
  
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