Self-assembly anchored film of two modified polyamide as promising cost-effective inhibitor for protecting carbon steel in neutral medium

Compared with small organic molecules, polymer corrosion inhibitors have more active adsorption centers and stronger self-assembly film-forming ability, which has become a research hotspot in the field of corrosion in recent years. In this study, two modified polyamides (MPA-1 and MPA-2) based on two low-cost materials (adipic acid and citric acid) self-assembled on steel substrate as polymer corrosion inhibitors, which were synthesized by facile condensation polymerization. The anti-corrosion performance of MPA-1 and MPA-2 was investigated by gravimetric and electrochemical methods, surface analysis and molecular dynamic simulations. Modified polyamide MPA as polymeric inhibitor exhibited remarkable performance (inhibition efficiency IE=86.68 % for 150 mg/L MPA-2) for Q235 carbon steel. Surface morphology results prove the degree of corrosion of Q235 steel with the addition of MPA-1 and MPA-2 was obviously reduced by self-anchored polymeric film. In addition, theoretical methods including quantum chemistry calculations and molecular dynamic simulations provide evidence at the microscopic scale level. [Display omitted] •Two cost-effective polymers are developed as corrosion inhibitor for steel.•Comprehensive evaluation of anti-corrosion performance of two polymers.•Self-anchored film is formed by polymers with multiple adsorption sites.•Theoretical calculations are used to reveal the mechanism of inhibition.