Drying study of siloxane-PPG nanocomposites

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dc.contributor.authorChaker, J. A.
dc.contributor.authorDahmouche, K.
dc.contributor.authorSantilli, Celso Valentim [UNESP]
dc.contributor.authorPulcinelli, Sandra Helena [UNESP]
dc.contributor.authorCraievich, A. F.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionLNLS
dc.date.accessioned2014-05-20T15:19:52Z
dc.date.available2014-05-20T15:19:52Z
dc.date.issued2000-12-01
dc.description.abstractThis is a study of the structural transformations occurring in hybrid siloxane-polypropyleneglycol (PPG) nanocomposites, with different PPG molecular weight, along the drying process. The starting materials are wet gels obtained by the sol-gel procedure using as precursor the 3-(trietoxysilyl)propylisocyanate (IsoTrEOS) and polypropylenglycol bis(2-amino-propyl-ether) (NH2-PPG-NH2). The shrinkage and mass loss measurements were performed using a temperature-controlled chamber at 50 degreesC. The nanostructural evolution of samples during drying was studied in situ by small angle x-ray scattering (SAXS). The experimental results demonstrate that the drying process is highly dependent on the molecular weight of polymer. After the initial drying stage, the progressive emptying of pores leads to the formation of a irregular drying front in gels prepared from PPG of high molecular weight, like 4000 g/mol. As a consequence, an increase of the SAXS intensity due to the increase of electronic density contrast between siloxane clusters and polymeric matrix is observed. For hybrids containing PPG of low molecular weight, the pore emptying process is fast, leading to a regular drying front, without isolated nanopockets of solvents. SAXS intensity curves exhibit a maximum, which was associated to the existence of spatial correlation of the silica clusters embedded in the polymeric matrix. The spatial correlation is preserved during drying. These results also reveal that the structural transformation during drying is governed by capillary forces and depends on the entanglement of polymer chains.en
dc.description.affiliationUNESP, Inst Quim, BR-14800900 Araraquara, SP, Brazil
dc.description.affiliationUSP, Inst Fis, BR-09500900 São Paulo, Brazil
dc.description.affiliationLNLS, Campinas, SP, Brazil
dc.description.affiliationUnespUNESP, Inst Quim, BR-14800900 Araraquara, SP, Brazil
dc.format.extent137-144
dc.identifierhttp://dx.doi.org/10.1023/A:1008703430829
dc.identifier.citationJournal of Sol-gel Science and Technology. Dordrecht: Kluwer Academic Publ, v. 19, n. 1-3, p. 137-144, 2000.
dc.identifier.doi10.1023/A:1008703430829
dc.identifier.issn0928-0707
dc.identifier.lattes5584298681870865
dc.identifier.lattes9971202585286967
dc.identifier.orcid0000-0002-8356-8093
dc.identifier.urihttp://hdl.handle.net/11449/31256
dc.identifier.wosWOS:000166544900019
dc.language.isoeng
dc.publisherKluwer Academic Publ
dc.relation.ispartofJournal of Sol-Gel Science and Technology
dc.relation.ispartofjcr1.745
dc.relation.ispartofsjr0,477
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjecthybrid materialspt
dc.subjectdrying processpt
dc.subjectsmall-angle X-ray scatteringpt
dc.titleDrying study of siloxane-PPG nanocompositesen
dc.typeArtigo
dcterms.licensehttp://www.springer.com/open+access/authors+rights
dcterms.rightsHolderKluwer Academic Publ
unesp.author.lattes9971202585286967
unesp.author.lattes5584298681870865[3]
unesp.author.orcid0000-0002-8356-8093[3]
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Química, Araraquarapt

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Artigos - Físico Química - IQ