DEPENDENCE OF SWELLING BEHAVIOR AND ELECTROCHEMICAL ACTIVITY OF WATER-SOLUBLE POLYTHIOPHENE FILMS ON THE NATURE OF THE ELECTROLYTE

Electrochemical activity of a cast film of a water-soluble polythiophe ne, poly(3-(3'-thienyl)propanesulphonic acid) (PTS), is examined in va rious electrolyte solutions. The PTS film is electroactive in 0.1 M te tra(n-butyl)ammonium perchlorate (TBAClO(4))+ acetonitrile. In contras t, the film is inactive in 0.1 M LiClO4 + acetonitrile, even in the pr esence of TBA(+), while addition of water (above 0.1 M) activates it. These characteristics are related to the film swelling; the PTS film i s electroactive only when it is swollen. Water swells the film rapidly and TBA(+) swells the film much more gradually. In the 0.1 M TBAClO(4 ) + acetonitrile, potential cycling accelerates the film swelling owin g to break-in behaviour. Well-swollen films do not exhibit break-in.