LONG-TERM REDOX SWITCHING STABILITY OF POLYPYRROLE

Polypyrrole (PP) films, including poly(pyrrole chloride) (PP-Cl), poly pyrrole/poly(styrenesulfonate) (PP/PSS) and poly(pyrrole p-toluenesulf onate) (PP-TOS), were synthesized from various electrolyte/solvent sys tems. The films were subjected to potential cycling to equilibrate the electroactivity in various switching media. In most cases, the use of a different solvent from the synthesis medium strongly decreased the electroactivity of the PP. The effect of this solvent exchange was str ongest in PP-Cl and relatively small in PP/PSS and PP-TOS. After equil ibration, the films were subjected to multiple potential steps between the reduced and oxidized states while monitoring the charge passed. T he electroactivity changes, measured as the amount of switching charge passed relative to the initial switching charge, were monitored with the number of double potential steps as a probe of the long-term stabi lity. In general, the order of long-term switching stability of PP was determined to be PP-TOS>PP/PSS>PP-Cl, with each system exhibiting uni que responses based on its electrochemical history.