The interaction of isomeric hexanediols with sodium dodecyl sulfate and dodecyltrimethylammonium bromide micelles

The micelle formation process for a typical anionic surfactant. sodium dode cyl sulfate, and a typical cationic surfactant, dodecyltrimethylammonium br omide, has been investigated in a series of mixed solvents consisting of di fferent concentrations of isomeric hexanediols (1,2-hexanediol and 1,6-hexa nediol) in water. The critical micelle concentrations and the degrees of co unterion dissociation of the mixed micelles were obtained from conductance experiments. Luminescence probing experiments have been used to determine t he concentration of micelles in solution and, hence, the micellar aggregati on numbers of the surfactants in the mixed solvent systems. The alcohol agg regation numbers were determined by combining the partition coefficients (o btained using NMR paramagnetic relaxation enhancement experiments) with the micellar concentrations from the luminescence probing experiments. All the se results are interpreted in terms of the difference in the interaction of the isomeric hexanediols with the surfactant as a function of the position of the hydroxyl groups on the six-carbon chain of the alcohol.