Structural Transitions in the System Water/Mixed Nonionic Surfactants/R (+)‐Limonene Studied by Electrical Conductivity and Self‐Diffusion‐NMR

Abstract

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., α wt%) when the water was replaced by 0.05M NaCl aqueous solution. It varies from 1.8 ×10⁻³ S/cm at α=10 wt% to 4.7×10⁻⁶ S/cm at α=90 wt%.

Keywords:

• Microemulsions
• percolation
• microstructure evolution
• hydrodynamic radius (R _H )
• area per head group (a)