Polyaniline has been electrosynthesized on mild steel in a two-step process
from aqueous electrolytes.:The first step, which acts as a pretreatment of
the surface, is the deposition of a thin polypyrrole film. It can be achie
ved in less than 3 seconds. It is followed by the electrodeposition of a PA
NI film of controllable thickness. Bilayer systems are thus generated. They
show electroactivity in acidic electrolyte similar to that of PANI deposit
ed on platinum, which indicates that the underlying oxidizable metal is ful
ly protected.