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 behav ior of both flat and curved liquid films with fluid-fluid interfaces. The method uses a specially designed glass cell for forming flat or cu rved films having different sizes and, thereby, different capillary pr essures. Our surface force balance equipped with this new cell in conj unction with differential interference microscopy was used to measure film thickness and disjoining pressure. This method is applicable to b oth symmetric foam and emulsion films, and asymmetric films such as th ose between approaching small oil droplets and an oil-water surface, o r water droplets and an air-oil surface. The results of the him thickn ess stability for the curved foam films were compared with those for t he plane-parallel films. It was found that, for thicker films (i.e. gr eater 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), th e curved micellar films stratified with a higher rate of thinning and had decreased thickness stability. (C) 1997 Elsevier Science B.V.