Change from a bulk to a surface coupling mechanism in the electrochemical polymerization of thiophene

The electrochemical polymerization of thiophene has been studied by spectrovoltammetric, spectrogal vanostatic and electrochemical quartzcrystal microbalance (EQCM) techniques. Experimental support was found for a change from a bulk to a surface coupling mechanism during the process at weakly adsorbing electrodes like indiumtin oxide (ITO). This conclusion has gained further proof from experiments in connection with the effect of a strong deprotonating agent (DBN). It was observed that the solution phase inhibitor is inefficient when it was added only during the process, when the surface had already been covered by a prepolymerized layer. The film formation undisturbed by the late addition of the inhibitor was illustrated by evidence obtained from spectroelectrochemical and EQCM measurements.