CHARGE FLUCTUATIONS AND SHEAR-STRESS OF THIN-FILMS

We consider the effects of lateral charge fluctuations on the linear s hear response of thin films. These fluctuations break the in-plane sym metry of the system and at short enough times cause the interaction en ergy to depend on the relative positions of the top and bottom surface s of the film. This gives rise to a shear stress which can be signific ant depending on the time scale of charge reequilibration and on the c harge and thickness of the film. The results have implications for the shear of charged membranes as well as the shear and frictional proper ties of electrolytes between two charged surfaces. [S0031-53007(98)076 69-8].