Effect of Counterion Substitution on AOT-Based Micellar Systems: Dielectric Study of Cu(AOT)2Reverse Micelles in CCl4

The effect of substituting Na + counterion of Aerosol-OT [sodium bis(2 ethylhexyl) sulfosuccinate] with doubly charged counterion Cu 2+ has been studied for the Cu(AOT) 2 /H 2 O/CCl 4 system by infrared and dielectric spectroscopy as a function of surfactant concentration and water content. A relaxation phenomenon has been observed whose behavior depends strongly on the degree of surfactant hydration W ( W = water-to-surfactant molar ratio). The hydration of Cu(AOT) 2 reverse micelles has also been investigated by means of IR spectroscopy. IR spectra of surfactant-entrapped water show a notable complexity, which could be ascribed to strong interaction between the Cu 2+ counterion and water inside the micellar core. The results of IR and dielectric spectroscopy studies have been compared and discussed with those previously obtained for the corresponding NaAOT and Ca(AOT) 2 reverse micelles.