Thermodynamic study on the adsorption and micelle formation of long chain alkyltrimethylammonium chlorides

The surface tension of aqueous solutions of tetradecyl-trimethylammonium chloride (TTAC) and decyltrimethylammonium chloride (DeTAC) were measured as a function of temperature at concentrations below and above the critical micelle concentration under atmospheric pressure. The entropy and energy of adsorption from the monomeric state and from the micellar state and also the entropy and energy of micelle formation for TTAC were evaluated and compared with those of dodecyltrimethylammonium chloride (DTAC). The values of Delta(W)(M)s and Delta(W)(M)u for TTAC and DTAC systems show that the micelle formation is driven by the entropy at low temperatures and by the energy at high temperatures.