Interfacial layer properties and foam film drainage kinetics of aqueous solutions of hexadecyltrimethylammonium chloride

Comparative studies of adsorption layer properties at the air/solution interface – dynamic and equilibrium surface tension measurements, surface dilatational rheology – and the drainage behaviour of microscopic foam films of aqueous solutions of hexadecyltrimethylammonium chloride (cetyltrimethylammonium chloride, CTAC), are performed within a broad surfactant concentration range. Two different concentrations of the added electrolyte (sodium chloride, NaCl) are investigated: 0.1 M and 0.5 M. The interfacial layer characteristics are studied using profile analysis tensiometer (PAT-1). The foam film drainage kinetics is investigated by the microinterferometric technique of Scheludko–Exerowa. Concerted onset of specific peculiarities is established for both adsorption layer properties and the foam film parameters. A remarkably good correlation is established between the run of the dynamic and equilibrium surface tension isotherms, the course of the surface dilatational elasticity and the peculiarities of drainage kinetics and film stability against the surfactant concentration within each of these concentration intervals. The obtained results shed additional light on the important role of the surfactant adsorption layers for understanding the details of microscopic foam film drainage and stability characteristics.