From sol to aerogel: a study of the nanostructural characteristics of TEOS derived sonogels

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dc.contributor.authorDonatti, D. A.
dc.contributor.authorRuiz, A. I.
dc.contributor.authorVollet, D. R.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T15:19:54Z
dc.date.available2014-05-20T15:19:54Z
dc.date.issued2001-11-01
dc.description.abstractThe nanostructural characteristics of acid-catalyzed sonogels are studied along the aging process at 60 degreesC in saturated conditions and after the CO, supercritical extraction (aerogel). The structural evolution was studied by means of small-angle X-ray scattering (SAXS) and UV-Visible absorption techniques. The sonogel exhibits a mass fractal structure in a length scale between zeta - 1/q(0) similar to 5.3 and a(1) similar to 1/q(m) similar to 0.22 nm, as the length scale probed by SAXS. The apparent mass fractal dimension lightly increases from 2.0 for fresh gel until 2.2 for 14 days aging in wet conditions. The UV absorption also increases with the aging time in wet conditions. Both observations are consistent with the syneresis process accompanying the polycondensation progress during aging in saturated conditions. For long aging times, the wet sonogels show a light transition from a mass to a surface fractal. in a very small interval of the length scale, developing an extremely rough surface with fractal dimension D-S similar to 2.9, the fractal characteristics of the sonogels practically do not change with the alcohol exchange. With the CO2 supercritical extraction (aerogel). The interval in the length scale in which the surface fractal is defined increases, while the surface fractal dimension diminishes to D-S similar to 2.5. The mass fractal characteristics are less apparent in the aerogels. (C) 2001 Elsevier B.V. B.V. All rights reserved.en
dc.description.affiliationUNESP, IGCE, Dept Fis, BR-13500970 Rio Claro, SP, Brazil
dc.description.affiliationUnespUNESP, IGCE, Dept Fis, BR-13500970 Rio Claro, SP, Brazil
dc.format.extent44-49
dc.identifierhttp://dx.doi.org/10.1016/S0022-3093(01)00891-2
dc.identifier.citationJournal of Non-crystalline Solids. Amsterdam: Elsevier B.V., v. 292, n. 1-3, p. 44-49, 2001.
dc.identifier.doi10.1016/S0022-3093(01)00891-2
dc.identifier.issn0022-3093
dc.identifier.lattes3538107401166553
dc.identifier.lattes5890636096105376
dc.identifier.lattes2661573794233385
dc.identifier.urihttp://hdl.handle.net/11449/31292
dc.identifier.wosWOS:000171993300003
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofJournal of Non-Crystalline Solids
dc.relation.ispartofjcr2.488
dc.relation.ispartofsjr0,722
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleFrom sol to aerogel: a study of the nanostructural characteristics of TEOS derived sonogelsen
dc.typeArtigo
dcterms.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dcterms.rightsHolderElsevier B.V.
unesp.author.lattes3538107401166553
unesp.author.lattes5890636096105376
unesp.author.lattes2661573794233385
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Geociências e Ciências Exatas, Rio Claropt

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