INTERACTIONS BETWEEN POLYANILINE AND SILVER CATIONS

Polyaniline (PAn) thin films were prepared from aniline solutions in H2SO4 by scanning the potential cyclically between -0.2 and 0.8 V (vs. SCE). Films of different thicknesses, and hence different intrinsic oxidation states, reacted differently with O.1M AgNO3. While redox reactions leading to the deposition of silver metal occurred between Ag+ and PAn in thick films (greater than or equal to 40 deposition cycles), thin films (less than or equal to 20 deposition cycles) favored the formation of a metal cation-polymer complex. The valency of silver in the polymer was determined by electrochemical measurements and x-ray photoelectron spectroscopy. Changes in polymer morphology due to the AgNO3 treatment were examined by scanning electron microscopy. It is suggested that the interactions between PAn and Ag+ could be applied to electrocatalysis and to the recovery of silver from aqueous solutions.