Estudo de filtros solares orgânicos e inorgânicos em sílicas mesoporosas ordenadas
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Data
2019-05-13
Autores
Silva, Leonardo Braile [UNIFESP]
Orientadores
Martins, Tereza da Silva [UNIFESP]
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
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Resumo
A SBA-15, devido as suas propriedades ímpares, tais como alta área superficial, tamanho e
volume de poro, alta estabilidade térmica e mecânica, pode incrementar as propriedades
fotoprotetoras do metoxicinamato de octila, OMC (filtro solar orgânico) e dióxido de titânio
nanométrico, TiO2 (filtro solar inorgânico), que devido à instabilidade química e térmica (OMC)
e aglomeração de partículas (TiO2) têm eficácia de fotoproteção reduzida. Neste trabalho,
compósitos SBA-15/TiO2, SBA-15/OMC e SBA-15/TiO2/OMC foram preparados e
caracterizados no intuito de analisar a estabilidade térmica e aglomeração das espécies em
estudo (TiO2 e OMC) e, também avaliar se a incorporação na SBA-15 oferece um incremento
nas propriedades fotoprotetoras dos compósitos. Os materiais foram preparados
empregando as metodologias de síntese direta e pós-síntese. A caracterização foi realizada
empregando diversas técnicas, tais como: espectroscopia de absorção na região do
ultravioleta e visível, espectrometria vibracional na região do infravermelho com
transformada de Fourier, análise termogravimétrica, difratometria de raios X a alto e baixo
ângulo, fisissorção de nitrogênio e microscopia eletrônica de varredura. Testes de
fotoproteção solar, in vitro, também foram realizados. Os compósitos SBAOMC (proporções
SBA:OMC de 1:1 e 2:1 em massa) preparados pelo método pós-síntese, empregando
impregnação via úmida em etanol, tiveram propriedades estruturais e morfológicas similares
a da SBA-15, indicando que o processo de incorporação do OMC na SBA-15 não causou
nenhum dano a matriz. Resultados de fisissorção de N2 indicam que o OMC se encontra nos
mesoporos da SBA-15 e a incorporação gera um incremento na estabilidade térmica do OMC
bem como no fator de proteção solar. O compósito SBA-15/TiO2 preparado por síntese direta
(porcentual molar de titânio de 20%) apresenta estrutura de mesoporos similar a SBA-15, mas
pequena diferença na morfologia. Apresenta a fase predominante rutila do TiO2 e quando
incorporado o OMC para produzir o compósito híbrido (SBA-15/TiO2/OMC) suas propriedades estruturais e morfológicas se mantêm com um incremento do fator de proteção solar do
compósito híbrido quando comparado com o OMC e TiO2 puros.
SBA-15, due to its unique properties, such as high surface area, pore size and volume, and high thermal and mechanical stability, can increase the photoprotective properties of octyl methoxycinnamate, OMC (organic filter) and nanometric titanium dioxide, TiO2 (inorganic filter), which due to chemical and thermal instability (OMC) and particle agglomeration (TiO2) have reduced photoprotection efficacy. In this work, SBA-15/TiO2, SBA-15/OMC and SBA- 15/TiO2/OMC composites were prepared and characterized in order to analyze the thermal stability and agglomeration of the studied species (TiO2 and OMC). the incorporation into the SBA-15 offers an increase in the photoprotective properties of the composites. The materials were prepared using the methodologies: direct synthesis and post-synthesis. The characterization was carried out using several techniques, such as: ultraviolet and visible spectrophotometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, wide and small angle X ray diffraction, N2 adsorption-desorption isotherms and scanning electron microscopy. Solar photoprotection tests, in vitro, were also performed. The SBA/OMC composites (SBA:OMC ratios of 1: 1 and 2: 1 weight) prepared by the post-synthesis method, using wet impregnation in ethanol, have similar structural and morphological properties as SBA-15, indicating the incorporation of the OMC into SBA-15 did not cause any damage structural to the matrix. N2 adsorption-desorption isotherms results indicate that the OMC is in mesopores of the SBA-15 and the incorporation generates an increase in the thermal stability of OMC, as well as in the solar protection factor. The SBA-15/TiO2 composite prepared by direct synthesis (20% titanium molar percentage) has a mesoporous structure like SBA-15, but a small difference in morphology. SBA-15/TiO2 composites presents the predominant rutile phase of TiO2 and when incorporated with OMC to produce the hybrid composite (SBA- 15/TiO2/OMC) its structural and morphological properties are maintained with an increase of the sun protection factor of the hybrid composite when compared to the OMC and TiO2 pure.
SBA-15, due to its unique properties, such as high surface area, pore size and volume, and high thermal and mechanical stability, can increase the photoprotective properties of octyl methoxycinnamate, OMC (organic filter) and nanometric titanium dioxide, TiO2 (inorganic filter), which due to chemical and thermal instability (OMC) and particle agglomeration (TiO2) have reduced photoprotection efficacy. In this work, SBA-15/TiO2, SBA-15/OMC and SBA- 15/TiO2/OMC composites were prepared and characterized in order to analyze the thermal stability and agglomeration of the studied species (TiO2 and OMC). the incorporation into the SBA-15 offers an increase in the photoprotective properties of the composites. The materials were prepared using the methodologies: direct synthesis and post-synthesis. The characterization was carried out using several techniques, such as: ultraviolet and visible spectrophotometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, wide and small angle X ray diffraction, N2 adsorption-desorption isotherms and scanning electron microscopy. Solar photoprotection tests, in vitro, were also performed. The SBA/OMC composites (SBA:OMC ratios of 1: 1 and 2: 1 weight) prepared by the post-synthesis method, using wet impregnation in ethanol, have similar structural and morphological properties as SBA-15, indicating the incorporation of the OMC into SBA-15 did not cause any damage structural to the matrix. N2 adsorption-desorption isotherms results indicate that the OMC is in mesopores of the SBA-15 and the incorporation generates an increase in the thermal stability of OMC, as well as in the solar protection factor. The SBA-15/TiO2 composite prepared by direct synthesis (20% titanium molar percentage) has a mesoporous structure like SBA-15, but a small difference in morphology. SBA-15/TiO2 composites presents the predominant rutile phase of TiO2 and when incorporated with OMC to produce the hybrid composite (SBA- 15/TiO2/OMC) its structural and morphological properties are maintained with an increase of the sun protection factor of the hybrid composite when compared to the OMC and TiO2 pure.