Triggering the Shrinking/Swelling Process in Thin Gel Layers on Conducting Surfaces by Applying an Appropriate Potential.

Negatively charged, pH-sensitive, very thin gel layers with accumulated hexaammineruthenium (II)/(III) were deposited on conducting surfaces. The gel was synthesized by applying an electrochemically induced free-radical polymerization method. This method allowed covering the electrode surface with an uniform and compact layer. The modified electrodes exhibited excellent current switch on/off behavior in response to changes in pH. However, the main goal of this study was to achieve the control of the layer thickness by changing the oxidation state of hexaammineruthenium. The layers could be reversibly swollen/shrinked by applying appropriate potentials.