Preparação e caracterização de materiais híbridos à base de sílica e de caulinita para diferentes aplicações

• Ano de defesa: 2010
• Autor(a) principal: Ribeiro, Lilian Rodrigues Ávila
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade de Franca; Brasil; Pós-Graduação; Programa de Doutorado em Ciências; UNIFRAN
• Palavras-chave em Português: Híbridos orgânico-inorgânicos; Química - Sol gel; Argilominerais; Caulinita - Sílica; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.cruzeirodosul.edu.br/handle/123456789/786

In this work inorganic-organic hybrid materials were developed using the sol gel route and from the natural clay kaolinite. The materials developed using the sol gel route were prepared from the tetraethylorthosilicate, phenyltriethoxysilane, and, phenyltrichlorosilane precursors with hydrochloric or phosphoric acid (acid catalysis) and ammonium hydroxide (basic catalysis) used as catalysts. The influences of different silicon precursors, of the addition time of the precursor phenyltriethoxysilane, and of the acid and basic catalyst were investigated. Europium chloride (III) was added in Si in a molar ratio of 1% Eu3+ act as a structural probe. The structure of these materials was investigated by means of thermal analysis, scanning electron microscopy, 29Si and 13C magnetic nuclear resonance, infrared absorption spectroscopy, and photoluminescence. The thermal analysis and 29Si and 13C magnetic nuclear resonance showed that the thermal stability and hydrolysis degree depend on the acid or base catalysis and precursors used for preparation of the materials. The photoluminescence of Eu3+ ions displayed that the surroundings can be modified depending on the different catalysis and precursors. The scanning electron microscopy showed that the type of catalyst also influenced the morphology of materials. The materials synthesized from natural kaolinite clay were prepared with the alkoxysilanes aminopropyltriethoxysilane and mercaptopropyltrimethoxysilane. The objective of this study was investigating the influence of different silicon precursors used for the preparation of these materials. The resulting materials were characterized by X ray diffraction, infrared absorption spectroscopy, thermal analysis, and scanning electron microscopy; which demonstrated the effectiveness of the interlamellar grafting process. The diffraction patterns revealed incorporation of the alkoxide molecules into the interlayer space of the clays. The displacement of the stretching bands of interlayer hydroxyls in the infrared spectra of the modified kaolinites confirmed the functionalization of the kaolinite.