Micellization Behavior of Aerosol OT in Alcohol/Water Systems

This paper examines the effects of solvent composition on the micellization behavior of the surfactant Aerosol OT (AOT). The critical micelle concentrations of AOT in the pure solvents methanol, ethanol, propanol, and isopropanol were measured using conductiometric techniques. These solvents were then mixed with water to create solvent spectra from pure alcohol to pure water in 12 increments. Critical micelle concentrations were measured at each solvent composition. Dynamic light scattering was used to verify the presence or absence of micelles in the solvent mixtures. It was found that inverse micelles exist over a range of solvent compositions where epsilon(eff) < 48 with CMCs increasing with increasing solvent polarity. Micellization was found not to occur when 48 < epsilon(eff) < 80. Regular micelles formed in pure water, with the measured CMC agreeing with the literature value of 2.25 mM.