Advanced synthesis and multifaceted characterization of a 4,4-diaminodiphenylmethane-melamine-formaldehyde terpolymer: anti-corrosion performance and antimicrobial potential in 1 M hydrochloric acid

Abstract

Herein, a 4,4-diaminodiphenylmethane-melamine-formaldehyde (DMF) terpolymer was synthesized and characterized to investigate its anti-corrosion properties for mild steel in a 1 M hydrochloric acid electrolyte. The DMF terpolymer produced through condensation polymerization was characterized using FTIR, ¹H NMR, ¹³C NMR, and gel permeation chromatography. Electrochemical tests showed that it achieved 94% inhibition efficiency at 100 ppm, functioning as a mixed-kind inhibitory agent. The adsorption phenomenon conformed to the paradigms delineated by the Langmuir adsorption isotherm, indicating strong binding through physical and chemical interactions. AFM confirmed the creation of a protective barrier on the steel substrate, while DFT studies supported its molecular adhesion. Additionally, the terpolymer exhibited antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis.