Transport across an electroactive polymer film in contact with media allowing both ionic and electronic interfacial exchange

In this paper, the general theory of coupled electron-ion transport inside a film having a mixed electron-ion coductivity is applied, and the a.c. imp edance expressions have been calculated for the situations where the film c an exchange electrons and/or ions with the surrounding media. Important exa mple of such system is given by a conducting polymer film between two solut ions containing a redox active couple ("redox active solutions") which is s ubjected to a faradaic process at the film surface with the participation o f electronic species inside the film. As particular cases, the general form ula describes also the systems where one or both interfacial boundaries can only be crossed by one type of charged species, electrons or ions. Besides the previously analysed situations, metal/film/ metal, metal/film/backgrou nd solution, or a film between two background solutions, we have obtained e xpressions for impedance of the film between a redox active solution and a background (without redox species) one, or between a metal and a redox acti ve solution. Theoretical predictions for the shapes of complex impedance pl ots in the case of a redox active solution have been demonstrated. (C) 1999 Elsevier Science Ltd. All rights reserved.