Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-07-19Bitstream added on 2014-06-13T20:06:32Z : No. of bitstreams: 1 sigoli_fa_dr_araiq.pdf: 3331714 bytes, checksum: f15f140dd71661951c9acd489ff18e44 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho, obteve-se uma matriz porosa com alto teor de sílica a partir de vidros Pyrex® utilizando-se o tratamento hidrotérmico. A matriz porosa é formada principalmente por dois processos: (i) reação da água no estado supercrítico com a rede vítrea e, (ii) separação e lixiviação de fases. A matriz apresenta-se macroporosa, possuindo também baixa percentagem de micro e mesoporos. Através de técnicas espectroscópicas verifica-se que a matriz apresenta grupos silanóis de superfície, os quais foram utilizados em reações de funcionalização. A espectroscopia de ressonância magnética nuclear de 29Si, MAS RMN, indica a presença de grupos ordenados, (SiO)4Si, no interior da matriz e do grupo (SiO)3Si(OAl). Os espectros de 29Si, CPMAS RMN, indicam que a matriz porosa é constituída de átomos de silício localizados em dois ambientes químicos diferentes, (SiO)3Si(OH), e (SiO)4Si. Pelo espectro de 27Al MAS RMN confirma-se a presença do grupo Al-O-Si, o qual é responsável pela formação de sítios ácidos de Brönsted. Pela análise dilatométrica verifica-se que a contração máxima da matriz foi de 6% em 1365oC, aumentando a densidade do material, o tamanho médio dos poros, devido a consolidação de micro e mesoporos, diminuindo assim a área superficial. A matriz cristaliza-se em 950oC como α-cristobalita pertencente ao grupo espacial P41212. A matriz obtida foi então utilizada como suporte para complexos luminescentes. O complexo diaquatris(tenoiltrifluoroacetonato)európio(III), [Eu(tta)3(H2O)2], impregnado ou ancorado na matriz, apresenta emissões com alargamento não-homogêneo indicando que há interações entre o complexo e a superfície da matriz... / In the present work, porous silica matrix has been obtained from Pyrex glass by hydrothermal treatment under saturated steam condition. The formation process was principally investigated using scanning and transmission electron microscopies and Raman spectroscopy. The results indicate that the process of phase separation takes place on edge of vitreous sample at lower temperature than of glass-transition temperature at room atmosphere. This process occurs due to the glass hydration by hydrothermal treatment that diminishes both viscosity and glass transition temperature. The segregated orthoborate phase was leached out by water in supercritical condition. The formation and leaching of this phase together with essential reactions between water and silica at supercritical condition contribute to obtain a porous silica matrix. The matrix has a high percentage of porosity, an interconnected macroporous structure, a low percentage of micro and mesopores and also a good thermal stability. It is non-crystalline and after thermal treatment it presented X-ray pattern characteristic of cristobalite and a low contraction of volume. The chemical analysis shows a high concentration of silicon and low concentrations of aluminum and boron. The chemical environments of silicon and aluminum atoms into the porous silica matrix were investigated by solid state NMR spectroscopy. The 29Si MAS NMR spectrum exhibits a broad signal at -110 ppm, typical of an ordered silica phase. The chemical nature of surface was better understood with application of the 1H - 29Si CPMAS NMR technique. This technique leaded to a strong and selective... (Complete abstract, click electronic access below)

Resumo: Neste trabalho, obteve-se uma matriz porosa com alto teor de sílica a partir de vidros Pyrex® utilizando-se o tratamento hidrotérmico. A matriz porosa é formada principalmente por dois processos: (i) reação da água no estado supercrítico com a rede vítrea e, (ii) separação e lixiviação de fases. A matriz apresenta-se macroporosa, possuindo também baixa percentagem de micro e mesoporos. Através de técnicas espectroscópicas verifica-se que a matriz apresenta grupos silanóis de superfície, os quais foram utilizados em reações de funcionalização. A espectroscopia de ressonância magnética nuclear de 29Si, MAS RMN, indica a presença de grupos ordenados, (SiO)4Si, no interior da matriz e do grupo (SiO)3Si(OAl). Os espectros de 29Si, CPMAS RMN, indicam que a matriz porosa é constituída de átomos de silício localizados em dois ambientes químicos diferentes, (SiO)3Si(OH), e (SiO)4Si. Pelo espectro de 27Al MAS RMN confirma-se a presença do grupo Al-O-Si, o qual é responsável pela formação de sítios ácidos de Brönsted. Pela análise dilatométrica verifica-se que a contração máxima da matriz foi de 6% em 1365oC, aumentando a densidade do material, o tamanho médio dos poros, devido a consolidação de micro e mesoporos, diminuindo assim a área superficial. A matriz cristaliza-se em 950oC como α-cristobalita pertencente ao grupo espacial P41212. A matriz obtida foi então utilizada como suporte para complexos luminescentes. O complexo diaquatris(tenoiltrifluoroacetonato)európio(III), [Eu(tta)3(H2O)2], impregnado ou ancorado na matriz, apresenta emissões com alargamento não-homogêneo indicando que há interações entre o complexo e a superfície da matriz...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the present work, porous silica matrix has been obtained from Pyrex glass by hydrothermal treatment under saturated steam condition. The formation process was principally investigated using scanning and transmission electron microscopies and Raman spectroscopy. The results indicate that the process of phase separation takes place on edge of vitreous sample at lower temperature than of glass-transition temperature at room atmosphere. This process occurs due to the glass hydration by hydrothermal treatment that diminishes both viscosity and glass transition temperature. The segregated orthoborate phase was leached out by water in supercritical condition. The formation and leaching of this phase together with essential reactions between water and silica at supercritical condition contribute to obtain a porous silica matrix. The matrix has a high percentage of porosity, an interconnected macroporous structure, a low percentage of micro and mesopores and also a good thermal stability. It is non-crystalline and after thermal treatment it presented X-ray pattern characteristic of cristobalite and a low contraction of volume. The chemical analysis shows a high concentration of silicon and low concentrations of aluminum and boron. The chemical environments of silicon and aluminum atoms into the porous silica matrix were investigated by solid state NMR spectroscopy. The 29Si MAS NMR spectrum exhibits a broad signal at -110 ppm, typical of an ordered silica phase. The chemical nature of surface was better understood with application of the 1H - 29Si CPMAS NMR technique. This technique leaded to a strong and selective... (Complete abstract, click electronic access below) / Orientador: Marian Rosaly Davolos / Coorientador: Miguel Jafelicci Junior / Banca: Aldo José Gorgatti Zarbin / Banca: Hermi Felinto de Brito / Banca: Henrique Eisi Toma / Banca: Sandra Helena Pulcinelli / Doutor

The fabrication characteristic of focused ion beam (FIB) for Pyrex glass was investigated. FIB has several advantages such as high sensitivity, high material removal rates, low forward scattering, and direct fabrication in selective area without any etching mask, etc. In this study, FIB etched Pyrex glass was used for fast fabrication of 3-D submicron structures. A high-aspect-ratio (HRA) glass structure of 5 (1.97µm depth/0.39µm width) was fabricated. The experimental results in terms of limiting beam size, ion dose¡]ion/cm2¡^, beam current, etc was discussed. Xenon difluoride (XeF2) was applied to enhance the FIB process. Its influence on glass fabrication is studied and characterized.

Focused Ion Beam (FIB) has several advantages such as high sensitivity, high material removal rates, low forward scattering and directing fabrication. Without any etched mask, processing time can be reduced. Pyrex glass etched by FIB is used for fast fabrication of 3-D submicron structure mold. In this study, glass is used as substrate. The UV-cured resin that spin-coated onto a mold has 3-D structure patterns. 3-D structure patterns are transferred on the plate to investigate the effects of parameters of UV cured, pressure and exposure time on the occurrence of defects. The relationship of these processing parameters for the imprinting process is also realized. Besides, the material property of UV-cured resin is investigated. UV-Cured resin is investigated by thermogravimetric Analysis (TGA) to measure the degradation temperature (Td). The hardness and modulus of UV-Cured resin was measured by nanoindentation to realize deformed ability of material for the imprinting process. Moreover, the contact angle of Pyrex glass is measured to investigate its surface quality for the imprint process.

No description available.