Combining electrochemistry and direct force measurements: from the control of surface properties towards applications

Direct force measurements contributed in the last years much to our understanding of the diffuse double layer of charged interfaces in electrolyte solutions. Such measurements have been performed with the atomic force microscope or the surface force apparatus. This review gives an overview over the recent studies based on force measurements with electrode surfaces. Not only bare metal electrodes but also electrodes modified by different organic layers, including electroactive films, have been studied by these techniques. Direct force measurements indicate that further effects besides classical Gouy-Chapman-Stern theory have to be taken into consideration in order to describe the force profiles. In addition to the long-range forces also the adhesion between surfaces can be tuned by potentiostatic control. New single-molecule techniques based on the atomic force microscope allow to probe the extension of polymer strands or their desorption from solid interfaces. In combination with electrochemistry, it became now possible to tune the desorption behavior of polymer strands or to measure the electromechanical coupling of motors from single strands of electroactive polymers.