Multicolor-expressible ECD materials consisted of polyanilines, and an anionic quinone

Summary form only given. Two polyanilines, polyaniline (PANI) and poly(o-phenylenediamine) (PoPD), were easily prepared onto a transparent indium-tin oxide (ITO) electrode as stable films by electropolymerization of the corresponding monomers. Clear electrochromism was observed for the PANI film (colorless / green) and the PoPD film (colorless / brown). Several anionic quinones such as 1-amino-4-bromo-antraquinone-2-sulfonic acid (BA) have a variety of colors and the colors of their reduced form, dihydroxybenzenes, are different from those of the original quinones. If the quinones are immobilized onto the ITO electrode, they are expected to act as ECD materials with various color changes. The possibility was examined using BA. Unfortunately, however, BA was not adsorbed on the ITO electrode. Besides, the electrode reaction of dissolved BA was found to be very irreversible. In order to immobilize BA on the ITO electrode and to enhance the reversibility of the electrode reaction, the PANI or PoPD films are precoated on the ITO electrode. The PANI- or PoPD-film coated electrode was polarized in an aqueous 0.1 M H/sub 2/SO/sub 4/ solution containing BA by repeated potential scanning. The polarization lead that BA was incorporated into the PANI or PoPD film due to the doping reaction of PANI or PoPD. The redox wave of the BA incorporated was evident in the cyclic voltammogram of the PANI / BA film and the reversibility of the redox reaction was greatly enhanced. As a result, the PANI / BA film showed clear electrochromism with a three-color change.