Synthesis of polymorphous of nanoparticulate alumina has been the subject of many works. The stabilization of these nanoparticles in aqueous suspensions is necessary in many technologic application and industrial products. Recently, a number of routes have been developed using various dispersants to prepare these nanoparticles dispersed in aqueous solution. In this work, nanoparticulate alumina prepared by precipitation and freezing drying was investigated as potential material for aqueous dispersion. These nanoparticles were dispersed in methylethylglycol (MEG), polyvinylalcohol (PVA) and polymethacrylate (PMA). The alumina nanoparticles and the dispersions were characterized physical-chemically and tested in the preparation of thin films.

Crystalline films of pure titanium oxide have been prepared on soda lime slide glasses by sol-gel process and dip-coating. The definition of various parameters such as chemical concentration, viscosity, catalyst type and withdrawal speed led to the preparation of transparent, crystalline and adherent coatings with hydrophobic characteristics. Their crystalline structure was evaluated as anatase phase by low angle X-ray diffraction. Thicknesses were measured by perfilometry, and the refractive indices were determined from transmittance spectrum taking into consideration the layers deposited onto the two sides of the substrate. Porosity was also estimated by UV-visible spectroscopy by using the Lorentz - Lorenz equation. The average grain size was evaluated by atomic force microscopy. The thicker and denser films presented hydrophobicity, which decreased when the film porosity increased.