Designing a smart epoxy anti-corrosion coating loaded with molybdate-doped polythiophene nano-hybrid self-assembled multi-walled carbon nanotube

Abstract

Novel epoxy (EP) composite coatings having high anti-corrosion durability were designed using multi-walled carbon nanotube (MWCNT) tailored with molybdate (Mo) anions doped polythiophene (Thp) nano-hybrid. The morphology, as well as structure of the oxidized MWCNT (MWC) with and without inhibitors, was characterized by various identification techniques. Using electrochemical tests, the nano-hybrid's ability to release inhibitors in the solution and its inhibition impact were investigated. The steel plate immersed in the saline solution containing MWC.Thp.Mo extract showed a high corrosion mitigation index, so its total resistance (RT) after 48 h reached 2671 Ω.cm2, while its resistance in the saline solution without extract was 930 Ω.cm2. The log |Z| (10 mHz) of the EP coating modified with MWC.Thp.Mo nano-hybrid is reported to be 10.78, which displays significant improvement in the barrier resistance of the EP coating after nano-hybrid inclusion (Log |Z| (10 mHz) = 9.46). The ability of active protection by the creation of a stable protective layer at the scratched area of the MWC.Thp.Mo.EP coating has been demonstrated with electrochemical impedance spectroscopy (EIS). Adsorption of inhibitors on the MWCNT surface led to a better distribution of nano-hybrid, resulting in the mechanical properties improvement of the epoxy coating. Also, the strong interaction between the coating and the metal has led to better adhesion and prevented the progress of corrosive agents at the interface, leading to lower loss of adhesion.