CTAB aggregation in solutions of higher alcohols: Thermodynamic and spectroscopic studies

The effect of organic additive, C8-OH and C9-OH (octan-1-ol and nonan-1-ol) on the micellar behavior of aqueous solution of cetyltrimethylammonium bromide, CTAB was examined by thermodynamic (density and speed of sound) measurements. The polar compounds form the additive-CTAB mixed micelles which cause micellar growth. The critical micelle concentration, cmc, and degree of counterion dissociation, α, of aqueous solution of CTAB containing different amounts of monohydric alcohols have been determined at various temperatures by means of electrical conductivity. Fluorescence method has also been used to obtain cmc values as well as the aggregation number, Nagg, of CTAB in the presence of studied alcohols. In general, the experimental results indicate that micelle formation is hindered by a rise in temperature. In addition, alcohols show an inhibitory effect on the formation of micelles of CTAB. The results are well supported by spectral studies viz. fluorescence and NMR.