Effect of various parameters on the conductivity of free standing electrosynthesized polypyrrole films

Electrical characteristics of polypyrrole films electrodeposited in different aqueous electrolyte solutions including p-toluenesulfonate, naphtalenesulfonate, nitrate, tetrafluoroborate, and perchlorate anions were investigated using the Van der Pauw procedure. The polymer films were synthesized by electrochemical oxidation at a fixed potential. Experimental parameters including the pyrrole concentration, electrolyte, applied potential and substrate were shown to affect the electrical conductivity σ of polypyrrole films. Since the substrate contributes significantly to the overall conductivity of polypyrrole-coated electrodes, the results obtained with free standing polymer films appeared more reliable. The results indicated that the p-toluenesulfonate doped PPy film showed the highest average conductivity (σ293 K = 4.5 × 105 S m−1) whereas the perchlorate doped one produced the lowest of all the films prepared (σ293 K = 2 × 104 S m−1).