Studies of controllabe colour change properties of polyaniline film

Summary form only given. It is well known that the colour of polyaniline film can be changed in suitable electrolyte by changing the electrode potential on the polyaniline film. this is the eletrochromic properties of polyaniline film. However, the coulour of polyaniline film in electrolyte is also dependent on the PH value of the electrolyte. this is the chemical sensitivity of polyaniline film. The colour distribution in two dimention space of electrode potential and PH value has been obtained, which describes the controllable colour change properties of polyaniline film in more detail. The dirrect factor of the colour change of polyaniline film is the hydrogen ion density in the film for both electrochromic property and chemical sensitivity mentioned above. It is demonstrated by photoluminescence spectra of PAn film at different presures and impedance spectra of PAn film with different colour that the colour of PAn film is interrelated tightly with the structure of the film. It is aiso well known that there is a forbiden area for controllalbe electrochromic property of PAn film in dark colour area. THe colour of PAn film in the forbiden area can not be changed once more. However, it is demonstrated by making a thorough study that the colour of PAn film in the forbiden area can be still changed at suitable electrochemical condition, then the range of controllable colour change of PAn film has been enlarged.