OPTIMAL SURFACTANT STRUCTURES FOR COSURFACTANT-FREE MICROEMULSION SYSTEMS .1. C16 AND C-14 GUERBET ALCOHOL HYDROPHOBES

In most surfactant formulations involving microemulsions, a cosurfactant is generally required in combination with a primary surfactant for several purposes; however, it has previously been shown not to be an absolute requirement and moreover surfactant hydrophobe structure has a profound effect on such requirements. After examining the phase behavior of several industrially feasible surfactants using oil phase composition, temperature, salinity, cosurfactant concentration, ethylene oxide number (EON), and propylene oxide number (PON) as variables, ethoxylated or propoxylated C-14 Guerbet alcohol sulfates are often found to form cosurfactant-free microemulsion systems with acceptable solubilization parameters (sigma*) over a wide variety of system conditions. The C-16 Guerbet alcohol sulfates are much more restricted in application, thus often requiring cosurfactant.