Effects of reaction conditions on the formation of poly(2-vinylpyridine) coatings by electropolymerization

The effects of reaction conditions on the formation of poly(2-vinylpyridine ) coatings on mild steel by electropolymerization have been investigated. O ver the ranges studied, the relative effects of these reaction conditions o n the weight of the coating produced is found to decrease as follows: monom er concentration > solution pH > methanol concentration > solution temperat ure. The optimum conditions for coating formation are to use a solution wit h a composition of 0.25 M 2-vinylpyridine, 15 vol% methanol, and pH 5.0 at a temperature of 20 degrees C. If the monomer concentration is too high, th e coating formed is soft and tacky; if it is too low, a thin and non-unifor m coating is produced. Methanol concentrations between 15 and 25 vol% are r equired to produce uniform and thick films. Coating weights decrease at ele ctropolymerization temperatures above 40 degrees C, presumably due to an in crease in polymer solubility. The polymer films become thicker and more uni form as electrolysis continues up to two hours. Ammonium perchlorate is fou nd to be the most suitable electrolyte for the process, although its actual concentration has little impact on film quality.