CHANGE FROM A BULK TO A SURFACE COUPLING MECHANISM IN THE ELECTROCHEMICAL POLYMERIZATION OF THIOPHENE

The electrochemical polymerization of thiophene has been studied by sp ectrovoltammetric, spectrogalvanostatic and electrochemical quartz-cry stal microbalance (EQCM) techniques. Experimental support was found fo r a change from a bulk to a surface coupling mechanism during the proc ess at weakly adsorbing electrodes like indium-tin oxide (ITO). This c onclusion has gained further proof from experiments in connection with the effect of a strong deprotonating agent (DBN). It was observed tha t the solution phase inhibitor is inefficient when it was added only d uring the process, when the surface had already been covered by a prep olymerized layer. The film formation undisturbed by the late addition of the inhibitor was illustrated by evidence obtained from spectroelec trochemical and EQCM measurements.