Abstract
In this article, new preparation techniques for size-controlled emulsions and their functions are described. Two preparation methods for nanoemulsions are discussed. The condensation method involves cooling single-phase microemulsions to a temperature below the solubilization phase boundary. The key process of the the second dispersion method is the homogenization of coarse emulsions with water phases containing large amounts of water-soluble solvents by a high-pressure homogenizer. An aqueous wax nano-dispersion was prepared through a cooling procedure of microemulsions. O/W cream containing surfactant and fatty alcohol also became transparent with a low viscosity through the reduction of emulsion droplet size. This technology could give lotion type cosmetics an excellent function that can be found in O/W cream. On the other hand, an extra large size emulsion (visible size emulsion) consisting of amphiphilic solid oil and liquid oil was developed. This formulation could provide a freshening feel in the early stages of application and an emollient feel after rubbing into the skin due to the extra large size of the emulsion. Although retinyl acetate was unstable against hydrolysis, the reduction of the oil/water interface area achieved by enlarging oil droplet size was also effective against hydrolysis.
