Self-assembled structures in thin liquid films

Abstract

A theoretical analysis of the new phenomenon of the so-called “black dots” is proposed. These are miniature non-spreading structures with radius about 5×10 −4 cm and are quite different from the conventional black spots observed in the thin foam films. They appear at low concentrations of the amphiphilic substance. The onset of the dots is explained via the assumption that a series of premicellar entities with various geometries exist at the interfaces and inside the thin film. At particular conditions, when the film becomes unstable, the structures begin to rearrange. This may lead to the outbreak of small-area thinnings with almost closely packed interface coverage that are registered as “black dots”. The proposed treatment is the first attempt to connect the appearance of “black dots” with the presence of the amphiphilic self-assembled structures in thin liquid films. Thus, it is shown that the microscopic thin-film investigations are very suitable for the identification and the study of premicellar species in the vicinity and at fluid interfaces.