Anticorrosion properties of smart coating based on polyaniline nanoparticles/epoxy-ester system

In this study, the anticorrosive effect of dodecylbenzenesulfonicacid-doped polyaniline nanoparticles [n-PANI (DBSA)] as a conductive polymer was investigated using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques. Initially, the n-PANI (DBSA) were successfully synthesized via inverse microemulsion polymerization leading to the spherical nanoparticles with an average diameter less than 30 nm. Two coating systems including 1 wt% n-PANI(DBSA) blended epoxy ester (n-PANI(DBSA)/EPE) and neat epoxy ester (EPE) were coated on the carbon steal substrate. The anticorrosion performance of the prepared coatings was studied using EIS measurement in 3.5% NaCl solution during 77 days. The experimental data was modeled using Zview software according to the appropriate equivalent circuit model. The results clearly showed the better corrosion protection of the n-PANI(DBSA)/EPE coating compared to the EPE coating. This behavior was attributed to the ability of n-PANI(DBSA) in releasing dopant anion when the corrosion process is initiated on the metal substrate emphasizing the smart protection of n-PANI(DBSA)/EPE coating. Accordingly, the released dopant anions along with the iron cations provide a secondary barrier layer, which passivates the substrate.

► We study the influence of PANI nanoparticles on anticorrosion behavior of EPE.
► Corrosion behavior was investigated carefully by EIS technique.
► We model the corrosion mechanisms using appropriate ECM.
► PANI nanoparticles increases greatly the anticorrosion properties of EPE coating.
► PANI/EPE coating protects the substrate through the smart mechanism.