Highly protective performance of water-based epoxy coating loaded with self-doped nanopolyaniline synthesized under supercritical CO2 condition

Abstract

Abstract In this study corrosion properties of water-based epoxy coating on carbon steel (CS) are improved by adding self-doped nano-polyaniline (SPAni) synthesized under supercritical carbon dioxide (ScCO 2 ) condition. The modified ScCO 2 -synthesized SPAni using water-based polyamidoamine hardener results in 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. Applying SP-WBE on CS substrate resulted in high improvement in corrosion properties compared to the similar coating without SPAni. Formation of oxide layers and adhesion properties of SP-WBE at corrosive medium were evaluated using scanning electron microscope (SEM). The transmission electron microscope (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 coating (blank sample) and SP-WBE coating on CS substrates were studied using salt spray standard test according to ASTM B-117, electrochemical impedance spectroscopy (EIS) and adhesion tests. EIS studies, after 1800 hrs of exposure to corrosive solutions, result in charge transfer resistance of 1.816E9 Ω and 8.64E7 Ω for SP-WBE and blank samples, respectively.