Conventional coatings act as temporary barriers to environmental assaults.
Rust and corrosion occur when a metal donates some of its electrons to oxygen, causing the formation of impurities that weaken the structure. This can be delayed by painting a metal or plating it with zinc or another, more reactive metal. Zinc, which is a good electron donor, reacts with oxygen, leaving the metal underneath unaffected. But there is a limit to how long paint and zinc coatings can last. Polyaniline works differently.