An imide-based organic polymer as an inhibitor for HRB400 steel in simulated concrete pore solution: Experimental and theoretical calculations

An organic nitrogen/oxygen-rich polymer (PFN-NDIN) was prepared via Suzuki reaction between 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-bis(3-N,N- dimethylaminopropyl)-9H-fluorene (FNB) and 4,9-dibromo-2,7-bis(3-(dimethyl-amino)propyl)naphthalenediimide (NDINBr 2 ) and utilized as a new inhibitor for HRB400 steels corrosion in alkaline medium of simulated concrete pore solution. The inhibition efficiency of this inhibitor was evaluated by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) results showed that the protective capacity of PFN-NDIN on HRB400 steel increased with increasing concentration to attain 92.85% efficacy with 400 ppm at 288 K. Potentiodynamic polarization (PDP) plots indicated that PFN-NDIN is effective and acts as a hybrid inhibitor. The adsorption behavior of PFN-NDIN was fitted and found to follow the Langmuir isothermal adsorption line, with discussion of the relevant thermodynamic parameters. The effect of temperature on this inhibitor's the rust-inhibiting effect was investigated. The surface was then studied, showing that the interfacial corrosion of HRB400 steel was inhibited by PFN-NDIN molecules. The relationship between PFN-NDIN molecules’ structure and the inhibition efficiency was investigated by quantum chemical calculations. Several parameters were calculated, the findings revealed that the prepared materials correlated well with their electronic contribution capability.