Designing of smart coatings of conducting polymer poly(aniline-co-phenetidine)/SiO2 composites for corrosion protection in marine environment

•Synthesis of poly(aniline-co-phenetidine)/SiO2 composite is carried out.•Coating formulation is made with different wt.% loading of copolymer composite.•Copolymer composite coating improves corrosion resistance by many orders.•High corrosion rate is maintained for long duration of exposure in marine environment.

Present study is focused on the development of conducting polymer based copolymer composite coating materials for corrosion protection of mild steel. Copolymer composites were synthesized by chemical oxidative copolymerization of an equimolar mixture of aniline and phenetidine. Coatings were developed by loading of these copolymer composites in epoxy resin. The electrochemical behavior of the coatings was studied in 3.5% NaCl solution by measuring the OCP variation with time, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The corrosion resistance of the coatings was observed to be improved remarkably on the incorporation of copolymer composites in the epoxy system. The EIS results explained the mechanism of the corrosion protection offered by the copolymer composites. The electrochemical results clearly demonstrated that the composite coatings with stand in 3.5% NaCl solution for even longer duration of immersion. Corrosion test results under accelerated conditions (as per ASTM B117 standards), of the composite coatings revealed almost no extended corrosion and blistering along the scribe mark.