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 unbuffer ed and buffered solutions at constant ionic strength. Cyclic voltammog rams, recorded at a sweep rate of 100 V/s, indicate that the films rem ain electroactive at pH values as high as 9 provided that the films ar e only switched between their leucoemeraldine and emeraldine states. T he 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 t he fast formation but slow reduction of the fully oxidized form of PAN I.