Abstract
Water is the best natural and sustainable cosmetic ingredient. Environmental awareness has been rising in recent years and the oil-free and water-based cleansing lotion market is growing. The characteristics of cleansing lotions—transparent appearance, low viscosity like water, and refreshing feeling—are preferred. However, there remains an issue that makeup can be removed insufficiently because the existing technology for cleansing lotion is based on an aqueous micellar solution of surfactants. In this study, we aimed at enhancing the removing capability of water-based cleansing lotion by using a self-assembly called a sponge phase with extremely low interfacial tension against lipophilic substances. Because of its structure swollen with a large amount of water, the sponge phase has interesting properties: transparent appearance and low viscosity, in spite of infinite aggregates assembled to form a three-dimensional network. We found that this phase can be obtained by controlling the phase equilibrium of a hydrophilic nonionic surfactant. By applying this technology to the cleansing lotion, we succeeded in the development of a new formula with high removing capability taking advantage of ultra-low interfacial tension, while retaining the water-like property. The technology is expected to be used not only for cosmetics that require good compatibility with skin, but also for any industrial applications that require ultra-low interfacial tension.
