A novel trans-esterified water soluble hyperbranched polymer for surface protection of X60 steel: Experimental and theoretical approach

The corrosion of metals remains a worldwide scientific challenge, as it affects the metallurgical, chemical, oil and gas industries and causes damages worth billions of dollars of economic loss annually. An ideal corrosion inhibitor should diminish the metal dissolution and provide an appropriate solution to mitigate or halt structural damage. For this purpose, trans-esterified water-soluble hyperbranched-carboxylate terminated polyamido-thioether (HCPATE) was designed, synthesized, and characterized by ¹HNMR, FTIR, and TGA analysis. HCPATE was evaluated as a new corrosion inhibitor for X60 steel in acidic medium through gravimeteric and corrosion inhibition analysis. The obtained results demonstrated that this polymer displays excellent inhibition against acid-induced corrosion on steel in the tested HCl solution. The corrosion inhibition efficiency improved with the concentration and attained a maximum of 94.86% at a 1000 ppm. The Tafel curves revealed that HCPATE performed as a mixed-type corrosion inhibitor with predominantly anodic efficacy. The impedance data illustrate a rise in polarization resistance with inhibitor concentration owing to the attachment of polymeric inhibitor macromolecules at the steel/acid interface. Moreover, structural analysis of steel surface after immersion indicates that HCPATE primarily performs as an inhibitor by forming thin inhibitor film over the steel substrate. Surface morphological and topographical results with contact angle measurements proved that the HCPATE produced a thin inhibitive film with hybrophobic surface. Theoretical simulations were also performed to corroborate the obtained experimental results.