Experimental evidences of self-assembly in foam films from amphiphilic solutions

Systematic foam film experiments are performed with amphiphile solutions. Specific film parameters are extracted which are related to the film lifetimes and reflect the coupling of film dynamics and the reorganization of surfactant assemblies present both in the film bulk and in the adsorption layers on its interfaces. A distinct qualitative sign of the above-stated coupling is the onset of peculiar unstable black patterns (black dots and "black spots"). Their occurrence is correlated with the plateau regions of the surface tension isotherms of the initial surfactant systems. The enhanced onset of the unstable black formations results in a sharp increase of the foam film lifetimes. This effect is interpreted as related to the disintegration of the amphiphilic structures in the process of film drainage. These experimental results are viewed as experimental evidences for the presence of amphiphilic structures in the primary surfactant solutions.