Effect of electrolysis factors on the formation of poly(2-vinylpyridine) coatings electropolymerized on Zn

The effects of electrolysis factors on the formation of poly(2-vinylpyridine) coatings electropolymerized on Zn substrate have been investigated by cyclic voltammetry technique. The amount of poly(2-vinylpyridine) coatings electropolymerized by cyclic voltammetry was significantly dependent on the pH of the bath and the maximum amount of coating was obtained at pH 5. This result suggested that the specific amount of proton in the bath should play an important role in the electropolymerization of 2-vinylpyridine. The morphology of the coatings was evidently affected by the hydrogen evolution. Under the electrolysis conditions where the hydrogen evolution rate was increased, the coatings contained many pits and streaks caused by vigorous hydrogen evolution. The poly(2-vinylpyridine) coatings produced by cyclic voltammetry were fine in the bath of pH 5 at 20 to 30°C. On the other hand, the current density for polymerization by chronoamperometry was abruptly decreased in the initial stage of two-dimensional coating formation, then it was subsequently decreased with an increase in the thickness of sound coating. The anode and cathode current density of Zn plate in 3% NaCl solution was decreased by poly(2-vinylpyridine) coating formation on it.