Behaviour of oil/water microemulsions upon dilution with water

The dilution of series of oil-in-water microemulsions, formulated with Aerosol-OT as surfactant, water, isopropyl myristate as oil and varying amounts of butanol as cosurfactant, was studied. An infinite dilution could be obtained only adding water containing surfactant; the minimum amount of Aerosol-OT required was determined. The behaviour of the microemulsions upon dilution was related to the presence of mixed micelles in the aqueous phase.