| In this thesis, the research results was reported, including the synthesis of nano-titania with different phases, particle sizes and morphologies, organic surface modification of nanosized TiO2 in rutile phase. The main content was concluded as follows:First the nanosized TiO2 with different phases, morphologies and sizes was prepared by hydrothermal method. The effects of pH value, hydrothermal temperature and hydrothermal time on the microstructure of nano-titania were investigated. The results show the pH value of precursor was the key factor in determining the crystal phase, particle size and morphology of nano-titania powder.Second it was found that the phase and morphology of TiO2 powder was changed in presence of glycol,propanetriol and tween-20. When Vglycol :VH2O≤1:1, the phase of TiO2 powder was brookite, while Vglycol :VH2O=3:1 and Vglycol :VH2O=5:1, the phase of product was anatase. TEM revealed that the spear shaped TiO2 particles with width of 20～40nm, length of 400600nm were combined by about nanocrystalline of 20nm, while Vglycol :VH2O=3:1.As Vpropanetriol :VH2O=1:1 and Vpropanetriol :VH2O=3:1 the willow leaf shaped in anatase phase was obtained, and while Vpropanetriol :VH2O=5:1 the phase of product changed into amorphous state . When Vtw20: VH2O=1:1, the phase of TiO2 powder was pure anatase. With increasing tween-20 concentration, the particle size of nanosized TiO2 became small and the product shape was changed into similar spherical particles from rod particles.Third azeotropic distillation method was used to the organic surface modification of nanosized TiO2 with lauric acid. The prepared samples were characterized by FT-IR,HRTEM,TG and DTG. The results confirmed that lauric acid linked inorganic nuclei by chemical bonds, and even monolayer coverage was obtained. The thickness of chemisorbed layer was l-2nm. After modification, the surface property of nanosized TiO2 was changed from hydrophilicity to hydrophobicity.
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