REDOX SWITCHING OF POLYANILINE FILMS - LOW-TEMPERATURE STUDIES

Polyaniline films can be switched rapidly between insulating (reduced) and conducting (oxidized) states. The kinetics of the processes invol ved in the redox switching have been studied using ultramicroelectrode s, which have the advantage that iR errors are minimized. The leucoeme raldine/emeraldine transformation has been studied in HClO4.5.5H2O ove r the temperature range 220 - 300 K. The polyaniline films can still b e switched rapidly at the lowest temperature studied. Potentiostatic o xidation transients exhibit a peaked shape characteristic of a nucleat ion and growth process. The monotonic reduction transients, on the oth er hand, are much faster and appear to be controlled by the RC time co nstant. The temperature dependence of the redox switching processes ha s been investigated and related to electron and proton transfer as wel l as to anion transport in the polymer film.