Redox Potential Distribution in the Presence of Mechanical Stress. The Case of Electroactive Polymers

Abstract

The current/potential response during the redox switching of electroactive polymers derived from substituted arylamines is analyzed in terms of a sigmoidal distribution of apparent formal potentials. This kind of polymers shows expansion and contraction during the redox switching. A thermodynamic analysis of these systems, including mechanical stresses developed during the oxidation and reduction cycles, leads to a distribution of apparent formal potentials. It is shown that the concept of electron binding can be applied to describe the redox switching of an electroactive polymer. On the basis of this concept, simple statistical thermodynamic models can be applied to describe the distribution of apparent formal potentials during the redox switching of this kind of polymers. In particular, a simple model based on the mean field approximation, including interaction between near neighbors, leads to a linear distribution of the apparent formal potential. On the other hand, a statistical thermodynamical model, including the development of strains during the redox switching, successfully describes the experimental sigmoidal distribution of apparent formal potentials.