Phase behavior and dielectric spectroscopy of the sodium dodecyl trioxyethylene sulfate/n-butanol/water system

The phase diagram of the ternary system of sodium dodecyl trioxyethylene sulfate (SDES)/n-butanol/water is obtained at (30.0 ± 0.1) °C. There exists a clear, isotropic, and low-viscosity L phase, which could be divided into W/O micelle, bi-continuous (B. C.) phase and O/W micelle by conductivity measurements. Dielectric Relaxation Spectroscopy (DRS) measurements are applied to investigate microstructure changes of this system. For samples with a fixed weight ratio, SDES/n-butanol = 3/7, DRS indicates a structure transition from W/O to O/W micelles via B.C. phase with the increase of water content. For the samples with a fixed weight ratio, SDES/H₂O = 4/6, DRS can presents that there exist changes of onefold structure size of W/O micelles as n-butanol content increases. The results obtained from DRS and their analyses are in good agreement with those from phase diagram and conductivity measurements.