Studies on Phase Behavior of CTAB/Octane/1-Butanol/Water Microemulsion

WT5”BZ]:Quaternary microemulsion of a cationic surfactant (cetyltrimethylammonium bromide, CTAB), octane, water, and 1-butanol has been investigated using conductivity and pulsed field gradient spin-echo NMR measurements. Conductivity and self-diffusion measurements were found to be self-consistent. In this system, the conductivity behavior has a distinct percolative phenomenon and a bell-shaped curve, which indicates that the single-phase microemulsion phase changes continuously from water-in oil microemulsion via bicontinuous microemulsion to oil-in-water microemulsion with increasing water contents. At the corner of the 1-butanol, water molecules have a rapid diffusion because the solubility of water in 1-butanol is relatively large. The self-diffusion coefficient of 1-butanol is larger than that of octane in the oil-in-water microemulsion domain due to the same reason.