The novel polythiadiazole polymer and its composite with α-Al(OH)₃ as inhibitors for steel alloy corrosion in molar H₂SO₄: Experimental and computational evaluations

Polymer/composite materials have been commonly used as corrosion inhibitors in different fields such as marine, oil field, and engineering industry due to their self-healing and thermal stability features. Herein, novel polythiadiazole, namely poly[(2,6-dicarbonylpyridine)(2,5-dihydrazinyl-1,3,4-thiadiazole)] (AMTP) via the interaction of 2,5-dihydrazinyl-1,3,4-thiadiazole with pyridine-2,6-dicarbonyl dichloride and its composite with α-Al(OH)₃-gel were designed in a good yield. The structures of the fabricated materials are characterized by FT-IR, NMR, SEM, and UV–Vis analyses. The protective action of AMTP and α-Al(OH)₃@AMTP on the C1018-steel corrosion in molar-sulphuric acid was evaluated by potentiodynamic-polarization (PDP) and electrochemical impedance spectroscopic (EIS) methods. PDP findings presented that the AMTP polymer and α-Al(OH)₃@AMTP composite performed as mixed-type inhibitors. The protection capacities of 90.3 and 97.6% were obtained in the presence of optimum dose 100 mg/L of AMTP polymer and α-Al(OH)₃@AMTP composite, respectively. The compound's adsorption on C1018-steel follows the Langmuir isotherm model. The SEM/EDX outcomes reveal that the C1018-steel interface is inhibited by AMTP polymer and α-Al(OH)₃@AMTP composite. DFT calculations exhibited that the efficiency of the prepared materials correlates well with their electron contributing capability, whereas simulations of Monte Carlo exposed that the favorability and extent of adsorption of additive molecules metal interface establish their corrosion protection routines.