Molybdate-doped sulfonated-polyaniline (SPni.Mo) grafted CNT nano-particles for fabrication of a dual-functional epoxy composite coating with durable corrosion resistance function

Carbon nanotubes nano-particles modified with organic-inorganic hybrid inhibitors, i.e., sulfonated polyaniline doped with molybdate (OMC.SPni.Mo) was designed to improve the anti-corrosion capability of carbon nanotubes for application in an epoxy polymer coating. The ability to release the inhibitors from the OMC.SPni.Mo surface in the saline solution at different pHs was demonstrated by EIS and ICP techniques. Epoxy resin reinforced with this nanohybrid, (OMC.SPni.Mo.EPoxy) was applied to the steel plate. EIS test outcomes revealed that after 90 days of immersion, the OMC.SPni.Mo.EPoxy sample did not show a significant change in the Log| Z|10mHz (≥10.5 Ωcm2). The OMC.SPni.Mo.EPoxy coating active corrosion mitigation after scratching was evaluated by the EIS technique and accelerated salt spray test. In this case, the total resistance reached 106.200 Ωcm2, which is 118% more than the pure coating. The improvement of the coating resistance is due to the film development in the scratched area and the prevention of corrosive agents from reaching the metal surface. The enhancement of the barrier protection against the progress of harmful ions in the coating-substrate interface and the adhesion of the OMC.SPni.Mo.EPoxy coating to the substrate compared to the sample coated with epoxy was presented by cathodic delamination and pull-off tests.