MICROELECTRODE STUDIES OF THE SWITCHING OF POLYANILINE FILMS IN UNBUFFERED AND BUFFERED SOLUTIONS

The oxidation and reduction of electrochemically produced polyaniline (PANI) films on platinum microelectrodes have been studied in unbuffered and buffered solutions at constant ionic strength. Cyclic voltammograms, recorded at a sweep rate of 100 V/s, indicate that the films remain electroactive at pH values as high as 9 provided that the films are only switched between their leucoemeraldine and emeraldine states. The electrochemically active fraction of the film depends on the buffer capacity of the solution and on the timescale of the experiments. The decreasing electroactivity with increasing pH is most likely due to the fast formation but slow reduction of the fully oxidized form of PANI.