ELECTROCHEMISTRY OF CONDUCTIVE POLYMERS .17. PREPARATION AND CHARACTERIZATION OF POLYTHIOPHENE IN AQUEOUS-SOLUTIONS

Polythiophene has been prepared in aqueous solutions by repeatedly cyc ling potentials between -0.25 similar to 1.75 V vs, the Ag/AgCl, satur ated KCl reference electrode. The polymer films thus prepared were den ser and more stable than those prepared in nonaqueous solutions. The f ilm could be doped both anodically and cathodically depending on the s olution pH. The films were not destroyed even when they are anodized a t +2.5 V in 0.2 M LiCl solution at pH 3.0 The polymer films have their maximum absorbances observed between 350 nm and 420 nm depending on t he electrolytes used, indicating the band gaps, and therefore chain le ngths, of the polymers could be significantly different in different e lectrolyte solutions. The impedance values of the polymer were affecte d strongly by the pH and applied potential.