OXIDATION-REDUCTION INTERACTIONS BETWEEN ELECTROACTIVE POLYMER THIN-FILMS AND AU(III) IONS IN ACID-SOLUTIONS

Polyaniline (PAN) and polypyrrole (PPY) were coated on pristine and ac rylic acid graft copolymerized low-density polyethylene (LDPE) films a nd exposed to chloroauric acid solutions. The reduction of Au(III) ion s in solution was followed using ultraviolet-visible absorption spectr oscopy. The structures of the PAN and PPY films after varying periods of immersion in the chloroauric acid solutions were analyzed using ult raviolet-visible absorption spectroscopy and X-ray photoelectron spect roscopy (XPS). In the process of reducing Au(III) to Au(0), the electr oactive polymers underwent degradation, evidenced by a gradual decreas e in electrical conductivity, ring substitution by chlorine, and a los s of material into solution. The degradation is due to the higher prop ensity of the polymers when existing in a higher oxidation state to un dergo hydrolysis reactions to soluble products.