Bicontinuous Microemulsion Type Cleansing Containing Silicone Oil. II. Characterization of the Solution and Its Application to Cleansing Agent

Abstract

In this study, bicontinuous microemulsions (D phase) was prepared by mixing decamethyl cyclopentasiloxane (DC), which is a good solvent for silicone soils, with cosmetic grade alkyl type surfactant polyoxyethylene (8 mol) glyceryl monoisostearate (PGMI) and ethanol aqueous solution. In the pseudo ternary phase diagram of DC/PGMI/15% ethanol aqueous solution system, a ME region exists from the water corner to the center of the ternary diagram. The ME solution solubilizes at most 15% of DC. However, by replacing half the amount of DC by a polar oil cetyl isooctanoate (CIO), the ME region extended continuously from the aqueous corner to the oil-rich region (60% DC). Self-diffusion coefficient measurement by using NMR and FF-TEM observation indicated a bicontinuous structure that solubilizes a large amount of oil and water for the oil-water ratios between 3/7-7/3. Detergency of cosmetic soils containing polymeric siloxane in the ME solution showed the highest value between the oil-water ratios of 1/1 and 7/3, where the ME with bicontinuous structure exists. These results show that bicontinuous type ME containing DC provides a good solution for cleansing silicone soils.