Synthesis of Monodisperse Fine TiO2 Particles by Aqueous Sulfuric Acid Droplets Solubilized by Reversed Micelles

概要

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Nanosize and monodisperse TiO<SUB>2</SUB> particles were tried to be produced by the hydrolysis of titanium tetraisopropoxide in a reversed micelle system. Spherical and amorphous particles with diameter of 30-200nm were produced in an aqueous sulfuric acid droplet solubilized reversed micelle that consisted of mixed surfactant of polyoxyethylene nonylphenyl ether (NP-6) and sodium 1, 2-bis- (2-ethylhexyloxycarbonyl) -1-ethanesulfonate (AOT). Infrared spectra suggested that a sulfate ion coordinated to two titanium atoms as a bidentate in the particles. The maximum particle size was found at the AOT mole fraction of O. 35 in the mixed surfactant. The particle size increased with increasing the molar ratio of sulfuric acid against the mixed surfactant and decreased with increasing the molar ratio of water. These effects on the particle size could be explained qualitatively from the number of sulfuric acid per unit reversed micelle. The washing of the particles with ammonia water, which eliminated sulfate ions, yield TiO<SUB>2</SUB> particles with reduced volume, which resulted in the decreased transition temperatures from amorphous to anatase form and from anatase to rutile form.
Japan Society of Colour Materialの論文