Anticorrosive performance of thiophene-based inhibitor-reinforced PVB coating on mild steel: an inclusive approach to the structural advantage of corrosion inhibitors

Abstract

Corrosion is a relentless adversary that undermines the integrity of critical infrastructures and industrial assets worldwide, leading to substantial economic losses and posing severe safety hazards. In this research, thiophene-based corrosion inhibitors such as DTT, DTP, and DTB were designed, developed, and characterized using standard techniques. The efficacy of these materials against corrosion on mild steel (MS) was evaluated by determining global reactivity descriptors through density functional theory (DFT), followed by potentiodynamic polarization studies. In a preliminary theoretical investigation, a lower band gap (2.54–2.69 eV) was observed for the synthesized inhibitors, and DTB exhibited higher electrical conductivity and chemical stability, indicating satisfactory corrosion-resistance properties. For effective binding and enhanced corrosion inhibition, the inhibitors were reinforced with polyvinyl butyral (PVB). Furthermore, potentiodynamic polarization measurements of the inhibitor-PVB combinations showed a significant positive shift in corrosion potential (E_corr) and a reduction in current density (I_corr), indicating effective inhibition of anodic and cathodic corrosive reactions. The DFT and potentiodynamic polarization results demonstrated that these thiophene-based inhibitors with an N-heterocyclic system can significantly reduce corrosion rates and enhance the durability of coatings due to structural advantages such as ortho substitution, the presence of nitrile groups, and the electron-donating capacity of the materials on the MS surface. Thus, the inhibition efficiency follows the order: DTB (97.68%) > DTT (91.94%) > DTP (91.67%). Finally, the research progress was in alignment with sustainable development goals for resilient infrastructure and sustainable industrialization.