A CO2-responsive anti-corrosion ethyl cellulose coating based on the pH-response mechanism

•A thiourea@PHMs nanoparticle is developed and the cumulative release of thiourea in the thiourea@PHMs changed with the content of CO2 in solution.•The ethyl cellulose coating with thiourea@PHMs addition obtains the self-healing property in NaCl solution with CO2 based on the pH-response mechanism.•The corrosion resistance of the ethyl cellulose based smart coating is enhanced in CO2 corrosion. A CO2-responsive coating has been developed by adding a thiourea-containing nanocontainer with pH-response release property into an ethyl cellulose coating. The cumulative release of thiourea in the nanocontainer changes with the pH of aqueous solution, which enabled the release rate of thiourea from the nanocontainer in coating to adapt to the change in corrosiveness of 3.5 wt. % NaCl with different dissolved CO2 content. The results of EIS and immersion experiments showed that this environmental responsive nanocontainer can significantly improve the corrosion resistance of the coating in 3.5 wt. % NaCl solution with and without CO2.