SCHEME FOR THE ANODIC AND CATHODIC TRANSFORMATIONS IN POLYTHIOPHENES

The unique symmetric voltammetric behavior of anodically and cathodica lly conducting 3'-thienylterthiophenes supports the analogous interpre tation of the anodic and cathodic transformations of thiophene type po lymers. The splitting of the anodic current peak during the reoxidatio n of the cathodically transformed film is connected to the presence of more conjugated segments presumably because of the side-chain thiophe nyl ring. According to the scheme both the anodic and cathodic process es leading to conductive forms start with the electrochemical oxidatio n or reduction of more conjugated segments. This can explain the blue shift in the absorbance of the neutral polymer in the UV-visible spect ra during the insulating-conducting transformation.