ELECTROCHEMOMECHANICAL DEFORMATION OF POLYANILINE FILMS

The deformation of unstretched and stretched polyaniline (PANI) films by the electrochemical cycle has been studied. An anisotropic deformat ion is observed. The largest expansion and contraction upon oxidation and reduction, respectively, are observed for the direction perpendicu lar to the draw axis. The deformation parallel to the draw axis is the smallest for oxidation leucoemeraldine salt to emeraldine salt (ES), and shows even slight contraction upon oxidation from ES to pernigrani line salt. The expansion ratio Delta l/l(D), where Delta l is the incr ement of expansion and eo is the original length, is found to be propo rtional to the degree of oxidation. In the unstretched film, Delta l/l (D) is about -2% at 20% reduction from the ES state. The results are d iscussed in terms of intercalation of dopant ions per repeating unit b etween chains and the conformational change of chains.