Highly Concentrated Emulsions Based on the Reverse Micellar Cubic Phase

The phase behavior of commercial lipophilic poly(oxyethylene)-poly(dimethylsiloxane) copolymer (PEOS), Me3SiO(Si(Me)2O)x-(SiMe(C3H6(OCH2CH2)nOH)O)ySiMe3 (x= 50-100, y= 1-5, n= 7-15, HLB value= 5), in water and water + oil systems was investigated by phase study and small angle X-ray scattering (SAXS). The lipophilic PEOS forms a reverse hexagonal liquid crystal (H2) phase in water, and the H2 + excess water phase exists at a low concentration. The H2 phase changes to a reverse micellar cubic (I2) phase with addition of oil. The I2 structure is identified to the Fd3m space group by SAXS. An excess water phase is also coexisted with I2 phase beyond the solubilization limit of water in the I2 phase and a large amount of water can be dispersed in I2 phase as emulsion droplets. As a result, highly viscous or stable gel-emulsion over 96% water as the internal phase could be formulated.