Effect of the N-Methylation of Dodecylammonium Chloride on the Adsorption from Its Micellar Solution
The surface tension of the aqueous solution of dodecylmethylammonium chloride (DMAC) and dodecyldimethylammonium chloride (DDAC) was measured as a function of temperature under atmospheric pressure at concentrations below and above the critical micelle concentration (cmc).The entropy and energy of adsorption from the monomeric state in the aqueous solution and the micellar state were evaluated by applying the thermodynamic equations of adsorption to the surface tension values.The thermodynamic quantities were compared with those of the aqueous solutions of dodecylammonium chloride (DAC) and dodecyltrimethylammonium chloride (DTAC).It was found that the successive N-methylation of DAC has a considerable effect on the adsorbed film with changes in its surface density, entropy, and energy brought about by changes in the geometry and the hydrophilicity of the polar head group.
