A SIMPLE CHEMICAL PROCEDURE FOR EXTENDING THE CONDUCTIVE STATE OF POLYPYRROLE TO MORE NEGATIVE POTENTIALS

The electronically conductive polymer polypyrrole is an electronic con ductor at potentials positive of ca. - 0.4 V vs. the saturated calomel electrode (SCE) and an electronic insulator at potentials negative of this value. As a result of this potential-dependent conductor/insulat or transition, a polypyrrole film can be used as an electrode for redo x couples with E-degrees positive of ca. - 0.4 V vs. SCE but cannot be used as an electrode for couples with E-degrees negative of this valu e. We have discovered a simple chemical procedure that extends the con ductive state of polypyrrole to ca. -1.1 V vs. SCE. This procedure ent ails treating the polypyrrole film with Aqueous sodium hydroxide. We d emonstrate this extension of the conductive state to more negative pot entials here. We also propose, and test, a chemical model that explain s the extension of the conductive state.