Stabilizing effect of polyglycerides as emulsifiers in cosmetic emulsions

Abstract

Emulsions are mixtures of two immiscible phases, a dispersed or internal phase and a dispersing or external phase, stabilized by different mechanisms depending on the emulsifier type. Emulsions are thermodynamically unstable, but their kinetical stability depends essentially on the type of emulsifier used. In this work simple emulsions are prepared, and it is analysed the stabilization effect of three different polyglycerides, non-ionic and natural origin surfactants resulting from the esterification reaction of fatty acids with some molecules of glycerine (in this case four molecules of glycerine). Moreover, three different glycerides are used as support agents (co-emulsifiers) made with the same fatty acid of polyglycerides; this way emulsions have the emulsifier and co-emulsifiers from the same fatty acid. The used compounds are derivatives from oleic, stearic and lauric acids. For each pair of compounds, the emulsion was characterized, and its stability was analysed. The results show that only oleic acid derivatives can be used to obtain emulsions with acceptable stability. The final goal of this work is to obtain a complete cosmetic formulation using the polyglyceride and glyceride that give the best results in the previous stability study. Since the prepared formulation is a moisturizing cream, the possibility of changing the usual oil (paraffin oil) by natural origin oils was also checked. This way the emulsions would have less allergenic reactions on skin and could be used in atopic skin cases