Effect of benzotriazole (BTA) addition on Polypyrrole film formation on copper and its corrosion protection

Benzotriazole (BTA) was added in a conducting Polypyrrole (PPy) film prepared on copper in oxalic acid aqueous solution containing pyrrole monomer to improve corrosion protection by the PPy film and reduce copper corrosion. When BTA was added in the preparation solution, the copper surface was covered by a BTA–Cu complex layer before the anodic polymerization of PPy was started. On the copper surface with the BTA layer, the initial dissolution of copper was inhibited and the PPy polymerization-deposition was started immediately after the anodic current was imposed. The PPy film thus formed was doped with oxalic ions and ionized BTA and was homogeneous in thickness and strongly adhesive. The PPy film containing BTA protected the copper from corrosion in 3.5 wt.% NaCl solution. In 400 h of immersion, copper dissolution was inhibited with 80% protection efficiency relative to that of bare copper.