Critical Micelle Concentration and HLB of the Sodium Oleate–Hexadecyltrimethylammonium Bromide Mixed System

Abstract

Abstract The critical micelle concentration of sodium oleate—hexadecyltrimethylammonium bromide mixtures was determined as a function of the mixture composition and analyzed with Rubingh's theory, showing a strong nonideality. The hydrophile–lipophile balance (HLB) of the mixtures was also measured and the validity of the additivity rule for the HLB of surfactants mixtures was tested. Results were compared with the aggregation behavior of that mixture. Both the HLB and the critical micelle concentration dependencies on the mixture composition exhibit a negative deviation when compared with ideal behavior, which is explained on the basis of the interactions between components and surfactant partitioning between the bulk and the interface.