TiO2 nanoparticles modified by oleic acid ( OA) were prepared using surface-modification method. Infrared spectroscopy (IR), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS) were used to investigate' the structure of the modified TiO_2 nanopartieles. Effects of OA concentration on coverage and dispersion in oil were also studied. The optimal proportion of OA to TiO_2 was established. The results indicate that the oleic acid is bonded to the surface of TiO_2 nanoparticles. The OA-modified TiO_2 nanoparticles have good dispersive capacity in organic solvent and mineral oil. An esterification mechanism for the surface-modification is proposed.

Key words: OLEIC ACID, TITANIUM OXIDE, IR, TEM, XPS, STRUCTURE CHARACTERISTICS