2024-03-28T20:01:21Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/524292016-02-17T09:17:05Zcom_10261_31com_10261_3col_10261_284
Rios, X.
Moriones, Paula
Echeverría, Jesús C.
Luquin, Asunción
Laguna, Mariano
Garrido, Julián J.
2012-06-28T09:47:09Z
2012-06-28T09:47:09Z
2011
Adsorption 17(3): 583-593 (2011)
http://hdl.handle.net/10261/52429
10.1007/s10450-011-9331-9
The mild synthetic conditions provided by the sol-gel process and the versatility of the colloidal state allow for the mixing of inorganic and organic components at the nanometre scale in virtually any ratio for the preparation of hybrid materials. Our interest in hybrid xerogels focuses on combining their porosity with other properties to prepare optic-fibre sensors. The specific aim of this paper is to synthesise hybrid xerogels in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane (TEOS) as silica precursors and to investigate the effect of the MTEOS molar ratio on the structure and porous texture of xerogels. Gelation time exponentially increased as the MTEOS molar ratio increased. Increasing the MTEOS molar ratio yielded xerogels with lower density and lower particle size. The incorporation of MTEOS resulted in new FTIR bands at 1276 and 791 cm-1, which was attributed to vibrational modes of methyl group. The band around 1092 cm-1 associated with siloxane bonds shifted to lower wavenumbers and split into two bands. The 29Si spectra only showed the Q n (n=2, 3, 4) signal in xerogels with 0% MTEOS and the T n (n=2, 3) signal in xerogels with 100% MTEOS; hybrid xerogels showed both Q and T signals. From XRD peaks at 2θ around 9°, we inferred that xerogels (>70% MTEOS) consisted of nanocrystalline CH3-SiO3/2 species. Increasing the MTEOS molar ratio produced xerogels with lower pore volumes and lower average pore size. The integration of methyl groups on the surface decreased the surface polarity and, in turn, the characteristic energy. © 2011 Springer Science+Business Media, LLC.
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Characterisation of hybrid xerogels synthesised in acid media using methyltriethoxysilane (MTEOS) and tetraethoxysilane (TEOS) as precursors
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