MICROSTRUCTURE AND DYNAMICS OF THE WATER-IN-OIL CTAB N-PENTANOL/N-HEXANE/WATER MICROEMULSION - A SPECTROSCOPIC AND CONDUCTIVITY STUDY/

Quaternary water-in-oil microemulsion of a cationic surfactant (cetylt rimethylammonium bromide, CTAB), n-hexane, water, and n-pentanol has b een investigated using conductivity, quasi-elastic light scattering, n ear-infrared absorption spectroscopy, and pulsed field gradient spin-e cho NMR measurements. The conductivity behavior shows features charact eristic of the migration of charged droplets. Consequently, using the charge fluctuation model, the conductivity data were correlated with t he droplet radius obtained from self-diffusion coefficients for differ ent obstruction factors. Conductivity and self-diffusion measurements were found to be self-consistent for spherical droplets with hard-sphe re interactions. Comparison between collective diffusion and self-diff usion coefficients fully supports this conclusion. The average head-gr oup area of CTAB, the amount of water free in the organic bulk, and th e fraction of alcohol present into the aggregates were evaluated toget her with the thickness of both the interfacial film and the bound wate r layer providing a full microscopic picture of the system.