Self-assembly of amphiphilic molecules in foam films

The structural reorganizations of smaller self-assembled aggregates (premicelles) in foam films are studied. The micellar entities form at lower amphiphile concentrations below the bulk cmc-value. A general theoretical scheme is proposed that connects the bulk theory of self-assembly with the specific interactions in the thin films. This scheme is used to suggest a model mechanism for the explanation of the following experimental observations: (1) at low surfactant concentration the surface tension/concentration curves (Delta sigma/C-s) display a well-defined Flat:eau sector; (2) in microscopic foam films obtained from a solution whose concentration is in the plateau region, the so-called ''black dots'' are observed. These are miniature nonspreading spots. The foam films that pass through this stage are unstable and break up quickly. The appearance of "black dots" is explained with the existence and the structural reorganization of the self-assembled structures inside the film and on its interfaces.