Lamellar liquid crystals made of anionic surfactant, oleic acid, diethyleneglycol monoethyl ether and water

Abstract

Lamellar liquid crystal formulation, with very low surfactant content, was optimized for the system made of phosphated oleyl ether 3 mol ethylene oxide as anionic surfactant, oleic acid as hydrophobic ingredient, diethyleneglycol monoethyl ether as cosolvent and water. The appropriate relationships between surfactant, fatty acid and glycol to promote the lamellar liquid crystal structure through further water dilution, were established. The physical appearance of these liquid crystals corresponded to viscous transparent gels. The realms of existence of the gels were stated in terms of minimum–maximum percentage of water incorporated. The main goal of this research was to decrease the surfactant content (in the range of 2–5%) needed to form liquid crystals, when usually high percentages are necessary. The study was completed with the rheological behaviour and structural parameters of some of these transparent gels. The attractive aspect of the samples, the perfect transparency and compactness, as well as the similarity to the lamellar liquid crystal structure of the intercellular lipids in the stratum corneum, permit consideration of such gels as adequate topical formulations both in cosmetics and pharmaceuticals.