Effect of film curvature on drainage of thin liquid films

Thin liquid films are considered to be the basic structural elements of foam and emulsion systems. Consequently, the structure and stability of macro-dispersions are highly dependent on the dynamic structure formation and stability of a single, thin, curved film between unequal-sized bubbles and droplets as in a polydispersed foam and emulsion system. A novel experimental technique based on the differential microinterferometric method has been used to investigate the dynamic behavior of such curved foam films. The simple theoretical drainage model of Reynolds was used to calculate the drainage time for both curved and plane-parallel films, and the results were compared with the experimental observations. It was found that for thicker films (i.e., greater than 100 nm), the curved film drained twice as slowly as the plane-parallel film. However, at a film thickness less than 100 nm, the plane-parallel film has a lower rate of thinning compared to the curved film. (C) 2002 Elsevier Science (USA).