Experimental Investigation of Eletrokinetic Stabilization of Gravitational Drainage of Ionic Surfactants Films

Gravitational drainage of vertical films of ionic surfactants supported on a frame with the upper and lower parts being electrodes is studied experimentally. The electric field introduces three additional physical phenomena: (i) the surface charge redistribution, which eventually changes surface elasticity, (ii) the electroosmotic flow in the diffuse layer, and (iii) pressure build-up near the electrode toward which the electroosmotic flow is directed. It is shown that stabilization of the films is possible either due to the traction imposed by the electroosmotic flow directed upward (against gravity), or due to the pressure build-up near the lower end of the frame, in cases where the electroosmotic flow is directed downward (in the gravity direction) and enters a dead end at the lower electrode.