Effect of 1-alkanoles on the critical micelle concentration of cetyltrimethyl ammonium bromide

The interaction of 1-alkanols (C-3-C-4, C-6 and C-8) with cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was studied by a conductivity method at 25.0 degrees C. The critical micelle concentration (CMC) of CTAB decreased linearly with an increase in the concentration of added I-alkanols within their low concentration regions. The water-micelle partition coefficient, K-x, and the standard free energy change of solubilization, Delta G degrees, of each alcohol from water to micelle were calculated from the limiting slopes, Delta CMC/Delta C,. The free energy of transfer per methylene group; Delta G degrees (CH2) has also been estimated, For 1-alkanols, K-x values increased linearly with the increase in the number of carbon atom, m(n), in the alkyl chain of respective alcohols.