EXTENT OF INCORPORATION OF HYDROLYSIS PRODUCTS IN POLYANILINE FILMS DEPOSITED BY CYCLIC POTENTIAL SWEEP

The ratio of the second anodic current peak at 0.52 V to the first anodic current peak at 0.17 V, I(p, B)/I(p, A), in the voltammogram of cyclic potential sweep (CPS) deposition of polyaniline (PANi) is used to measure the extent of incorporation of products of polymer degradation by hydrolysis during electropolymerization. In CPS deposition from HClO4 solutions, the ratio depends on such deposition conditions as the scan rate, the rotation speed of the electrode. the number of deposition cycles and the aniline concentration. The competitive reaction of aniline and water with an intermediate generated by PANi oxidation to the bipolaronic state, and the solubility of the resulting products, determine the amount of hydrolysis products to be incorporated in the polymer deposit. The presence of hydrolysis products in PANi inhibits fibrous growth and gives rise to a powdery film morphology. The ratio I(p, B)/I(p, A) is therefore useful as an index of film quality in practical applications.