Solid particles are adsorbed at air-liquid or liquid-liquid interfaces spontaneously, and form stable emulsions and foams. Some complicated structures, i.e. network and bicontinuous structures, have been found recently. Here, I show studies on the mechanism of self-assembly and the applications for industrial materials.

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Emulsifying properties of fine particles have been recognized over a century : colloidal particles with a suitable wettability can be strongly adsorbed at the oil-water interfaces, and can work as effective stabilizers for emulsions (Pickering emulsions). After a dormant period of nearly half a century, there is a revival of interests in studying their behaviour. Organic polymer particles have mainly been used in the form of film in paint and adhesive industrial sections. In addition to usage in the form of the film, there have been increasing interests in using the polymer particles in their particulate form. Recently, the polymer particles have found their application as emulsion stabilizers. This article presents an overview of current research activities that center on Pickering-type emulsions stabilized with well-defined smart polymer particles. It is organized into four parts : i) brief discussions of small particles adsorbed at oil-water interfaces; ii) demonstrations of Pickering-type emulsion stabilized with polymer particles; iii) demonstrations of soft material fabricated from Pickering-type emulsions; and iv) brief introductions of characterization methods of emulsions stabilized with polymer particles.

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Powders can stabilize emulsions by adsorbing the liquid-liquid interfaces. The phenomenon is also predicted that powders can adsorb and stabilize the ineterfaces between liquid and gas. So, a Powder emulsion is developed with the functional powders that have the optimized balance of hydrorepellency due to fractal surface and hydrophilicity due to free hydroxyl groups. By using the powders, we created a new powder technology that can encapsulate a large quantity of water softly. In this study we explain why the cosmetic is possible. At first we focused on hydrophilic and hydrophobic balance of nano-sized powder surface. We also looked into how the powders encapsulated water by observed with wet-SEM and how the encapsulated water is stabilized by measuring water mobility with ¹⁷O-NMR. Finally, we would introduce the application with many unique characteristics : the powder can change into liquid by application of friction.

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