Structuring oil phases in personal care products

Cosmetic emulsions are often used to deliver oil soluble actives from aqueous external phases. After these emulsions are applied to the skin or hair, the volatile phase evaporates, leaving behind the actives, surfactants and any other non-volatile component. The aesthetics from this type of emulsion is encountered on application, after evaporation of the water and after spreading out on the skin. Additionally, a major concern that often is overlooked is introduction of water on the skin by sweating, swimming or encountering rain. If not properly selected, the emulsifiers in the formulation can re-emulsify the oil phase and remove the actives or oils off of the skin.
This article will look at two different materials that will structure the oil phase of an emulsion. This structuring of the oil phase will have dramatic effects on the emulsion’s stability and performance. In vivo and in vitro SPF data will be presented to show the effect of these thickeners in sun care products, as well as microscope images and viscosity to demonstrate how these thickeners can be used to decrease the emulsifier concentration.