EFFECT OF MONOMER CONCENTRATION AND SUBSTRATE RESISTANCE ON REDOX BEHAVIOR OF POLYANILINE FILMS

The effect of monomer concentration and substrate resistance on the re dox properties of polyaniline is investigated using cyclic voltammetry . The mechanism of polymerization is found to be affected drastically by the concentration of monomer while the influence of substrate resis tance seems to become a predominant factor only at higher concentratio n. Both these parameters in combination are found to be responsible fo r the flattening of cyclic voltammograms due to a significant contribu tion of the uncompensated ohmic resistance. The extent of reversibilit y is observed to be a strong function of scan rate and the optimum oxi dation-reduction transformation occur at a scan rate of 100 mV s(-1) a t moderate monomer concentrations. Additionally, from the optical spec tra it is observed that 0.2 M monomer concentration is seen to be appr opriate for obtaining selectively the conducting phase of the polymer.