Microemulsions with Nonionic Surfactants and Mint Oil

A combination of electrical conductivity, dynamic viscosity, dynamic light scattering and small angle X-ray scattering methods was used to study the properties of the water + propylene glycol/mixed nonionic surfactants/ peppermint oil + ethanol U-type microemulsions which can be diluted with any amount of water. The surfactants were sucrose laurate and ethoxylated mono-di-glyceride. The mixing ratios (w/w) of the mixed surfactants and peppermint oil/ethanol equal unity and that of water/propylene glycol equals to two. The electrical conductivity and periodicity of the microemulsions increases with the aqueous phase content while the dynamic viscosity decreases. The variations in the values of the correlation length with the aqueous phase contents indicate the onset of structural transitions. Structural transitions from the water-in-oil to a bicontinuous phase then inversion to oil-in-water occurs in the system.