Separation of ionic processes in conducting polymers by fast current transients

Summary form only given. A computer supported pulse measurement system recently developed allows to record current transients between A and nA on a time scale between /spl mu/s and ks. An investigation of the redox process of PANI [1] showed that the oxidation of the reduced, semiconducting polymer is kinetically hindered. At first a conducting phase must nucleate. This formation is rate determining. Now, the redox process in electrochemically formed polyaniline (PANI) and poly-3-methyl-thiophene (P3MT) was investigated in dependence on the nature of the electrolyte anions. Sulphuric, perchloric, trichloroacetic and p-toluenesulphonic acid were used to exclude, the well-known influence of pH and electrolyte resistance on the redox behaviour. The current transients show a high influence of the doping anion on the charging kinetics. For PANI the current maximum shifts to longer times with increasing anion size. In contrast, current transients at P3MT exhibit a less distinct shape, the bigger the anion. Fast current transients were applied additionally to the separation of diffusion and charge transfer processes during the hydrogen evolution at conducting polymer films. The reaction can be located at the metal polymer interface. Thus, the hydrogen and proton transport through the polymer can be evaluated.