Critical Micelle Concentrations of Sodium Dodecyl Sulfate and Cetyltrimethylammonium Bromide Mixtures in Binary Mixtures of Various Salts at Different Temperatures and Compositions

Abstract

By conductivity method were examined the aggregation behavior of cationic amphiphile–cetyltrimethylammonium bromide (CTAB) and anionic amphiphile–sodium dodecyl sulfate (SDS) mixtures in binary mixtures of various salts. The values of critical micelle concentration (cmc) of SDS–CTAB mixtures lie between the cmc values of the pure amphiphiles. With temperature increasing the cmc values decrease first and then enhance with further rise of the temperature. The observed cmc of the SDS–CTAB mixed systems in attendance of binary mixture of salts was obviously less as compared to aqueous solution. The degree of counterion dissociation along with cmc value was utilized to evaluate different thermodynamic parameters. The values of interaction parameters and excess free energy were found to be negative in all cases. All results obtained reveal the strong interaction between the studied amphiphiles.