Anti-corrosive mechanism of poly(N-ethylaniline)/sodium silicate electrochemical composites for copper:Correlated experimental and in-silico studies

Poly(N-ethylaniline)(PNEA)composites with varying silicate content were fabricated on copper through a novel electropolymerized strategy in acidic solution.Thickness,compactness,conductivity and adhesive strength of the composite(PNEA-10 Si)were optimized as silicate content reached 10 m M.Electrochemical,morphological and solution analyses were employed to evaluate the protective performance of PNEA and PNEA-10 Si coatings for copper in 3.5%Na Cl solution.Results of electrochemical analyses indicated that as-prepared coatings retarded the oxygen reduction process efficiently for copper in 3.5%Na Cl solution,drained corrosion current density and elevated interfacial charge transfer resistance.Due to favorable barrier effect,compact structure and low porosity index,PNEA-10 Si composite exhibited superior anti-corrosive performance,which was more tolerant than PNEA during long-time immersion.PNEA-10 Si coated sample exhibited a stable topography after 144 h immersion with the minimum concentration of released ions revealing the improved protection capacity.Electronic/atomic-multiscale calculations were conducted to clarify the deposition and protection mechanism of as-prepared coatings.Outcomes of density functional theory corroborated that silicate is stabilized in the PNEA layer via electrostatic force;and immobile silicate positively contributed to the charge transfer barrier of the composite.Molecular dynamics simulations evidenced that the favorable compatibility between PNEA and silicate facilitated polymer deposition and confined in-situ ions diffusion.