Surface Modification of TiO<SUB>2</SUB> Particles with Various Normal-Chain Alcohols in Supercritical CO<SUB>2</SUB> as a Solvent
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概要
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Surface modification of fine TiO<SUB>2</SUB> particles with various normal-chain alcohols was conducted in supercritical CO<SUB>2</SUB> (scCO<SUB>2</SUB>) as a solvent using supercritical CO<SUB>2</SUB> method and immersion method. The modified fine TiO<SUB>2</SUB> particles were characterized by BET surface area, elemental analysis, FT-IR, XRD, particle size distribution, and dispersion test. The number of surface functional groups (<I>N</I><SUB>R</SUB>) on the samples was calculated from the results of elemental analysis and surface area. This value was available to evaluate the degree of the surface modification. <I>N</I><SUB>R</SUB> changed remarkably with reaction temperature, reaction pressure, and modification methods. Judging from the obtained results, the concentration of alcohol dissolved into scCO<SUB>2</SUB> and the character of scCO<SUB>2</SUB> affected on <I>N</I><SUB>R</SUB>. The effects of the use of scCO<SUB>2</SUB> as a solvent were as follows : (1) promote dehydration between alcohol and hydroxyl groups on TiO<SUB>2</SUB> surface, and (2) suppress the agglomeration of modified particles. It was also found that the hydrophobicity of modified samples improved with an increase in the number of carbon chains. Consequently, a newly developed organic- free process which is environment-friendly has been proposed.
- Japan Society of Colour Materialの論文