A study of polyindole perchlorate (PIP) prepared by electropolymerization

Abstract

AbstractPolyindole perchlorate (PIP) was obtained by electrochemical oxidation using a potential of 0.7 V as anodic precipitates. A cyclic voltammetry was performed in acetonitrile solution containing 0.2M indole and 0.1M tetraethylammonium perchlorate. The result suggested that this electrode reaction was reversible, and the peak width (ΔEp) of the anodic and cathodic peaks obtained was 58 mV. The result of IR measurements clarified that the polyindole was obtained by a 1,3‐polymerized mechanism. As for the ESCA analysis of the PIP pellet, besides a main N1s peak at 399.6 eV, a high binding energy peak at 402.3 eV was observed. Also, in the case of the C1s peak, besides a main peak at 284.6 eV, a shoulder peak at high binding energy was measured. These results suggested that an electropolymerization of indole was performed by the formation of radical cations. A thermogravimetric analysis was performed in a temperature range from 25 to 800°C. The rate of thermal decomposition (R) for the polyindole‐and polyaniline‐based polymers was calculated by a computer connected with a thermal analyzer. From the thermal analysis, it was concluded that the polyindole‐based polymers decomposed at higher temperatures than did the polyaniline‐based samples. The Rmax values of the polyindole systems were not related to the kind of dopants, but in the case of the polyaniline systems, they were seriously affected by the kind of electron acceptors. The electrical conductivity of the PIP pellet was performed in a temperature range from 150 to 25°C. The values of log σ at 25°C and Ea obtained were ‐1.63 s/cm and 0.508 eV, respectively. From the results, we suggested that a possible conduction mechanism and charge carriers for the PIP pellet were hopping conduction and polarons, respectively. The ESR measurements for the PIP powder were performed at room temperature, and the values of various ESR parameters were calculated. © 1992 John Wiley & Sons, Inc.