Gelation and drying of weakly bonded silica-PPO nanocomposites

dc.contributorUniversidade Estadual Paulista (UNESP)
dc.creatorChaker, J. A.
dc.creatorDahmouche, K.
dc.creatorSantilli, Celso Valentim
dc.creatorPulcinelli, Sandra Helena
dc.creatorCraievich, A.
dc.date2014-05-20T15:30:43Z
dc.date2016-10-25T18:06:20Z
dc.date2014-05-20T15:30:43Z
dc.date2016-10-25T18:06:20Z
dc.date2003-06-01
dc.date.accessioned2017-04-06T00:18:34Z
dc.date.available2017-04-06T00:18:34Z
dc.identifierJournal of Applied Crystallography. Copenhagen: Blackwell Munksgaard, v. 36, p. 689-693, 2003.
dc.identifier0021-8898
dc.identifierhttp://hdl.handle.net/11449/40048
dc.identifierhttp://acervodigital.unesp.br/handle/11449/40048
dc.identifier10.1107/S0021889803005089
dc.identifierWOS:000182284400066
dc.identifierhttp://dx.doi.org/10.1107/S0021889803005089
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/882862
dc.descriptionSilica-poly(oxypropylene) (PPO) nanocomposites containing PPO with weak physical bonds between the organic (PPO) and inorganic (silica) phases were obtained by the sol-gel procedure. Three precursor sols containing silica and PPO with molecular weights of 1000, 2000 and 4000g/mol were prepared. The structure changes during the whole sol-gel process, i.e. sol formation, sol-gel transition and gel aging and drying were investigated in situ by small angle X-ray scattering (SAXS). The experimental SAXS curves corresponding to sols and wet gels containing PPO of molecular weight 1000g/mol indicate that the aggregates formed during the studied process are fractal objects. Close to the sol-gel transition and during gel aging the fractal dimension is D=2.5. A clearly different structure evolution occurs in samples prepared with PPO with molecular weights 2000 and 4000 g/mol. Our SAXS results indicate the presence of two coexisting and well-defined structure levels, one of them corresponding to small silica clusters and the other to large silica aggregates. These two levels remain along the whole transformation. The SAXS curves of all dry samples are similar to those of the corresponding wet gels suggesting that no significant changes at nanoscopic scale occur during the drying process.
dc.languageeng
dc.publisherBlackwell Munksgaard
dc.relationJournal of Applied Crystallography
dc.rightsinfo:eu-repo/semantics/closedAccess
dc.subjecthybrids
dc.subjectsol-gel
dc.subjectSAXS
dc.titleGelation and drying of weakly bonded silica-PPO nanocomposites
dc.typeOtro


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