Self-assembly of tetradecyltrimethyl-ammonium bromide in long chain alcohols

Abstract

The effect of organic additives, C₈-OH and C₉-OH (octan-1-ol and nonan-1-ol), on the micellar behavior of cationic surfactant, tetradecyltrimethylammonium bromide (TTAB) has been studied by fluorescence and NMR techniques. Fluorescence spectroscopy has been used to obtain critical micelle concentration values as well as the aggregation number of TTAB in the presence of the studied alcohols. The decrease in cmc of aqueous TTAB is observed in the presence of long chain alcohols. The alcohols form additive-TTAB mixed micelles and micellar growth takes place. The structural transformation is explained by hydrophobic interactions and electrostatic effects between the additive and TTAB micelle. The locus of solubilization of alcohols and consequent changes in structure of the micelles is inferred from NMR measurements. The unique role of long chain alcohols in changing properties of aqueous surfactant systems is demonstrated.