Structural transitions in the system water/mixed nonionic surfactants/R (+)-limonene studied by electrical conductivity and self-diffusion-NMR

The system studied is water/sucrose laurate/ethoxylated mono di-glycerides/R (+)-limonene. The types of microstructure formed along the one phase microemulsion channel were examined using self-diffusion-NMR and electrical conductivity. The diffusion coefficients provide an evidence of the transition from oil-in-water to bicontinuous to water-in-oil microstructures. The hydrodynamic radius of the oil-in-water microemulsions increases as a function of temperature. Electrical conductivity was determined as function of temperature and oil content in the mixture of oil and water (i.e., alpha wt%) when the water was replaced by 0.05M NaCl aqueous solution. It varies from 1.8 x 10(-3) S/cm at alpha = 10 wt% to 4.7 x 10(-6) S/cm at alpha = 90 wt%.