Micellar properties of tetradecyltrimethylammonium nitrate in aqueous Tsolutions at various temperatures and in water-benzyl alcohol mixtures at T25 °C

The micellar properties of tetradecyltrimethylammonium nitrate (C14TANO3) in aqueous solutions in the temperature range of 10 to 35 °C and in aqueous solutions of benzyl alcohol (BzOH) at 25 °C were studied conductometrically. The specific conductivity data served for the evaluation of critical micelle concentration, cmc, and the degree of ionization of the micelles, , of the surfactant. From the temperature dependence of the cmc the thermodynamic parameters for micellization of C14TANO3 were calculated by applying Mullers modified equation. BzOH was found to affect strongly the cmc and values of the surfactant. The plot of the cmc\cmco ratio (where cmco is for pure water) as a function of BzOH molality, exhibits a characteristic break, which was attributed to the commencement of self-association of BzOH in aqueous solution at a molality of ca. 0.05. By applying the theoretical treatment suggested by Motomura for binary surfactant systems, the molar fraction of BzOH in the micelles at cmc, was estimated as a function of molality of the alcohol. C14TANO3 appears to be slightly more hydrophobic compared to the corresponding bromide.