A novel method for studying the dynamic behavior of both plane-parallel and curved thin liquid films

A new experimental technique was developed to study the thinning behavior of both flat and curved liquid films with fluid-fluid interfaces. The method uses a specially designed glass cell for forming flat or curved films having different sizes and, thereby, different capillary pressures. Our surface force balance equipped with this new cell in conjunction with differential interference microscopy was used to measure film thickness and disjoining pressure. This method is applicable to both symmetric foam and emulsion films, and asymmetric films such as those between approaching small oil droplets and an oil-water surface, or water droplets and an air-oil surface. The results of the him thickness stability for the curved foam films were compared with those for the plane-parallel films. It was found that, for thicker films (i.e. greater than 100 nm), the curved film drained at a slower rate than the plane-parallel film but, for thinner films (i.e. less than 100 nm), the curved micellar films stratified with a higher rate of thinning and had decreased thickness stability. (C) 1997 Elsevier Science B.V.