Optimization of transparent gels for cosmetic compositions

Abstract

AbstractThe necessary conditions were established by which several biocompatible ingredients (phosphated oleyl ether 3 mol ethylene oxide as surfactant, oleic acid as the lipophilic ingredient, and diethylene glycol monoethyl ether and 1,2‐propanediol as glycols) were combined to formulate transparent gels through dilution with water. This study was carried out at three constant levels of surfactant concentration (5, 10, and 15%), which determined in each case the appropriate ratios between the other three components to give transparent gels. These ratios were expressed as the global ratios between oleic acid and the two glycols together (ranging from 1∶9to 1∶3), whereas the internal ratios between the glycols moved in each case from 1∶0 to 0∶1. The systems with 5% of initial surfactant and a global ratio between oleic acid and the glycols of 1∶7 appeared to be the most effective for minimizing the final surfactant content. They furnished transparent gels at specified levels of water dilution, resulting in final surfactant concentrations in the range of 2–4%. Microscopic observation of the gels through polarized light showed the typical pattern of a lamellar liquid crystal structure. The mild characteristics of these gels, given their low surfactant content and the harmlessness of the other components, in addition to their attractive transparency and the rheological characteristics of plastic fluids make them suitable for application as topical formulations in the cosmetic or pharmaceutical fields.