  In this research, corrosion properties of water-based epoxy coating is
improved by adding self-doped nano polyaniline (SPAni) synthesized using
supercritical carbon dioxide (ScCO2) medium. The modified ScCO2-synthesized
self-doped nano polyaniline (SPAni) using water-based polyamidoamine hardener
results formation of the water-based SPAni composite (Sc-WB). To obtain the
water-based polyaniline epoxy coating (SP-WBE), the Sc-WB was mixed with epoxy
resin in stoichiometric ratio. The formation of oxide layers and adhesion
properties of SP-WBE at corrosive medium was evaluated using scanning electron
microscopy (SEM) studies. The transmission electron microscopy (TEM) was used
to observe the distribution and particles size of nanopolyaniline in the final
dried film. The anti-corrosion performance of water-based epoxy coated sample
(blank coated sample) and SP-WBE coated sample was studied using salt spray
standard test according to ASTM B-117, electrochemical impedance spectroscopy
(EIS) and adhesion tests. The results indicate protective performance of
water-based epoxy coating is improved by adding self-doped polyaniline
synthesized at ScCO2 situation. The electrical resistance of the coatings
containing nanopolyaniline and the blank sample was 1.8778E+7 {\Omega}.cm2 and
2.512E+5 {\Omega}.cm2 after 1800 hours of immersion in 3.5 Wt% NaCl aqua
corrosive solutions.
