Surface modification of fine TiO2 particles with various normal-chain alcohols was conducted in supercritical CO2 (scCO2) as a solvent using supercritical CO2 method and immersion method. The modified fine TiO2 particles were characterized by BET surface area, elemental analysis, FT-IR, XRD, particle size distribution, and dispersion test. The number of surface functional groups (NR) 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. NR changed remarkably with reaction temperature, reaction pressure, and modification methods. Judging from the obtained results, the concentration of alcohol dissolved into scCO2 and the character of scCO2 affected on NR. The effects of the use of scCO2 as a solvent were as follows : (1) promote dehydration between alcohol and hydroxyl groups on TiO2 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.
Glossy application is one of the most important characters of lipsticks. One of the major interfering factors of the gloss is aggregate of wax (e.g. paraffin or polyethylene) used as shape retentioner of sticks ; the aggregate deteriorates the surface smoothness of the applied lipstick film. We have found that poly (alkyl methacrylate) (PAMA) dissolves the aggregates and consequently enhance the application gloss dramatically. Our improved colloid prove AFM measurement using polyethylene microsphere suggests that PAMA adsorbed on the surface of wax crystals generates repulsive force, and then improves the dispersion of the crystals in the applied film.