Analytical Basis of ion separation by use of growth of conducting zones associated with electrochemical switching of conducting polymers

点击翻译按钮获取中文摘要

The electric conductivity of an aromatic conducting polymer film on an electrode can be altered drastically by varying the electrode potential in a dopant solution, because the doping and the undoping processes behave like an electrode reaction. When positive potential is applied to the film, the conducting zone grows and propagates from the electrode toward the solution until the film becomes the fully conducting state. The appearance of the phase boundary is ascribed to the electronic conduction of the oxidized species which works as a metal-like electrode for the electrochemical reaction with the reduced (insulating) species. This property may be sensitive to ionic species because ions are sensitive to the conduction state. This work has been devoted to application of this property to separation on ions. At first, the percolation threshold potential, which is significant for the switching behavior, was determined under quasistatic conditions. The was helpful for estimating potential domains of appearance of the conducting zone. Secondly, the inverse process was investigated with a help of spectroscopy, and was found to include slow relaxation. Thirdly, an interesting technique of evaluating electric conductivity by use of mgnetically induced current was found and developed. This was not predicted in advance, and is new information supported by this project. Forthly, study of the pH dependenae of the switching is going on now, which may lead to analysis of ion separation..