Adsorption of dodecyltrimethylammonium chloride from the micellar solution at water/air interface

The surface tension of the aqueous solution of dodecyltrimethylammonium chloride (DTAC) was measured as a function of temperature under atmospheric pressure at concentrations below and above the critical micelle concentration. The thermodynamic quantity changes associated with the adsorption of DTAC from its monomeric and micellar states were evaluated and proved to satisfy the thermodynamic relation derived on the assumption that the micelle formation can be treated as the appearance of a macroscopic bulk phase in the solution. Further their values were compared with those of the aqueous solution of dodecylammonium chloride and the influence of the chemical structure of the head group on the adsorption and micelle formation were discussed from the thermodynamic viewpoint.