Surface engineering: corrosion protection using conducting polymers

Adherent and homogenous polyaniline and polypyrrole films were electropolymerized onto iron from aqueous oxalic acid and phosphoric acid solutions, respectively, while copolymers of polyaniline and polypyrrole were formed on aluminium from a tosylic acid solution. In all cases, the polymers exhibited good corrosion-protection properties. In the case of iron, the polypyrrole–phosphate system showed more superior corrosion-protection properties than the corresponding polyaniline–oxalate system. This was attributed to the greater stability of the phosphate layer deposited at the iron electrode.