Híbridos orgânicos - inorgânicos fotocrômicos obtidos pelo processo sol gel pelos métodos de hidrólise e solvólise

• Ano de defesa: 2017
• Autor(a) principal: Cruz, Raul Pereira da [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Organic-inorganic hybrids; Photochromic; Sol gel; Polyoxometalate; Diureasil; Híbridos orgânicos-inorgânicos; Fotocrômicos; Polioxometalatos
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5111806; http://repositorio.unifesp.br/handle/11600/49915

Organic-inorganic (HOI) hybrids called di-ureasils obtained by the sol gel process are good candidates for the development of photochromic materials by the synergism between their organic and inorganic parts and the ability to incorporate phosphotungstic acid (PWA). In this work HOI, of the di-ureasil type, were synthesized from two diamines with different molar masses (400 and 2000 g.mol-1) and with different concentrations of PWA, using the sol gel process by the hydrolysis and solvolysis methods (formic, valeric and acetic carboxylic acids). The influence of PWA concentration, solvolysis and hydrolysis routes and the effect of polymer chain size on the photochromic properties were studied. The materials were characterized by X ray diffraction (XRD), thermal analysis (TG / DTG), differential scanning calorimetry (DSC), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and absorption spectroscopy in the UV-Vis region. FTIR and raman showed that PWA structure is preserved in the matrix and the interactions between them occurs mainly in the urea group of the polymer chain. The structures of the matrices with and without PWA are amorphous. TG/DTG curves showed that materials are thermal stable until approximately 300 oC and DSC curves indicated that glass transition temperatures increase as a function of the PWA content and size of the polymer chain due to a decreasing of the polymer chain mobility. Both hybrid families U(400) e U(2000) presented photochromic affect as a function of the PWA content and synthetic route.