CHEMICAL ATTACK ONPOLYPYRROLE BY ELECTROLYTICALLY GENERATED SOLUTION SPECIES IN AQUEOUS CHLORIDE MEDIUM

This paper describes a new type of polypyrrole film instability brough t about by electrolytically generated solution species. Specifically, electrolytes containing ''aggressive'' anions such as chloride in conj unction with hydroxyl ions emanating from the cathode cause the genera tion of hypochlorite at the corresponding anode in a single-compartmen t cell. These electrolytically generated species then attack the polyp yrrole film causing it to undergo facile dissolution. A variety of tec hniques, including quartz crystal microgravimetry, potentiometry, UV-v isible spectrophotometry, Raman spectroelectrochemistry, and gas chrom atography/mass spectrometry, were used to monitor this process. Remark ably enough, this chemical reaction may be turned ''off'' by maintaini ng a negative potential at the polypyrrole/electrolyte interface such that the migration of OCl- to the polymer film is inhibited.