Publicação: Structural features of silicas prepared in n-heptane/water/ethanol/sodium dodecylsulfate microemulsions
Nenhuma Miniatura disponível
Data
2012-05-01
Orientador
Coorientador
Pós-graduação
Curso de graduação
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Tipo
Artigo
Direito de acesso
Acesso restrito
Resumo
Silica aerogels were prepared from hydrolysis of tetraethoxysilane (TEOS) in n-heptane/water/ethanol/ sodium dodecylsulfate (SDS) microemulsions and ambient pressure drying (APD). APD was carried out after silylation of the wet gels surface with trimethylchlorosilane (TMCS). The samples were studied by small-angle X-ray scattering (SAXS) and nitrogen adsorption. The structure of the wet gels can be described as a mass-fractal with fractal dimension D = 2.2, independently of the oil phase quantity, in a length scale which extrapolates the experimental range 0.4 nm < 1/q < 13 nm probed by SAXS. The fractality range is shortened with silylation and APD process in a mechanism in which share of the porosity is eliminated and the silica particles increase. Typical values for surface area and pore volume obtained for APD aerogels are comparable with those obtained by supercritical drying. The pore volume increases and the pore size distribution shifts toward the macropore region with increasing the oil phase. The mass-fractal features obtained from nitrogen adsorption are in good agreement with the SAXS results. (C) 2012 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
Idioma
Inglês
Como citar
Microporous and Mesoporous Materials. Amsterdam: Elsevier B.V., v. 153, p. 204-209, 2012.
