Resumo em português Filmes finos de PMMA foram preparados a partir de solução e expostos ao plasma de CF4+H2, visando mudar o Índice de Refração (I.R.) da superficie do PMMA através da fluoração. Os filmes de PMMA expostos ao plasma, denominados de filmes ópticos, foram caracterizados usando as técnicas: ESCA, RBS, FTIR, gravimetria, ângulo de contato, refratometria e elipsometria. Os resultados revelaram que as superfícies de PMMA foram revestidas com uma fina camada de hidroflu (mais) orcarbono polimérico, com espessuras variando entre 0,43 e 0,49mim. A camada de hidrofluorcarbono polimérico na superfície do PMMA foi responsável pela significante redução do seu I.R. de 1,49 para 1,43. A concentração de flúor nessa camada aumentou gradualmente em função da profundidade, sendo menor na sua superficie. Como o átomo de flúor é responsável pela redução do I.R., concluiu-se que o I.R. no revestimento fluorado do filme óptico variou também de forma gradual. A técnica de polimerização por plasma de CF4+H2 mostrou-se útil para modificar in situ os I.R. da superfíces de guias de ondas e fibras ópticas poliméricas, visando reduzir as perdas e aumentar a velocidade de transmissão de dados. Resumo em inglês Fluorinated PMMA optical films were obtained using the CF4+H2 plasma polymerisation technique. The characterisation analysis: ESCA, RBS, FTIR, gravimetry, contact angle, refractometry and ellipsometry, revealed that a hydrofluorcarbon polymer was deposited on the optical films exposed to the plasma. Fluorine concentration increased gradually with the fluorinated film depth (0.43-0.49mum). A refractive index 1.42-1.43 was found on the surface of the fluorinated films, lowe (mais) r than the PMMA (1.49). This fluorinated layer could present a gradient refractive index, being reciprocal of the Fluorine concentration. The potential advantages to obtain graded-index polymer waveguides and optical fibres are loss reductions and higher transmission rates.
Resumo em inglês This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful at (mais) tainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm.
Resumo em inglês In this work the formation of multilayers composed by carboxymethylcellulose (CMC), chitosane and bovine serum albumin (BSA) was studied by ellipsometry. First, the adsorption behavior of carboxymethylcellulose onto amino-terminated surfaces was investigated as a function of molecular weight and average degree of substitution of CMC. The influence of these parameters on the adsorbed amount of CMC onto amino-terminated substrates was absent. However, the interaction of CMC (mais) covered surfaces with chitosane and BSA was favored when the average degree of substitution of CMC was increased. The adsorption of BSA onto the polysaccharide systems was studied as a function of pH. At the isoelectric point of BSA a maximum in the adsorbed amount was found.
Resumo em inglês In this study cellulose acetate butyrate (CAB) and carboxymehtylcellulose acetate butyrate (CMCAB) films adsorbed onto silicon wafers were characterized by means of ellipsometry, atomic force microscopy (AFM), sum frequency generation spectroscopy (SFG) and contact angle measurements. The adsorption behavior of lysozyme (LIS) or bovine serum albumin (BSA) onto CAB and CMCAB films was investigated. The amounts of adsorbed LIS or BSA onto CMCAB films were more pronounced th (mais) an those onto CAB films due to the presence of carboxymethyl group in the CMCAB structure. Besides, the adsorption of BSA molecules on CMCAB films was more favored than that of LIS molecules. Antimicrobial effect of LIS bound to CAB or CMCAB layers was evaluated using Micrococcus luteus as substrate.
Resumo em inglês Polysaccharide-based drilling fluids have been often applied in horizontal wells of petroleum reservoirs in Campos, Rio de Janeiro. The present study aimed to understand the mechanism of adsorption and desorption of the drill-in fluid, xanthan, modified starch and lubricant on SiO2 by means of ellipsometry. The effect of pH and brine on the mean thickness (D) of adsorbed layer was systematically investigated. The adsorption was mainly favored under alkaline conditions. A (mais) model has been proposed to explain this effect. The adsorption isotherms determined separately for xanthan and starch on SiO2 surfaces could be fitted with the Langmuir model, which yielded similar adsorption constant values.