A novel phthalocyanine based discotic liquid crystal for efficient corrosion inhibition of mild steel

Abstract

ABSTRACT Discotic liquid crystals have been extensively investigated for their applications in electro-optical devices. Very recently their potential as corrosion inhibitor has been realised. Effective methods for the prevention of corrosion of mild steel (MS) are still challenging research for industrial chemists. In the present work, MS samples in 1.0 M HCl medium were used to test the corrosion inhibition capacity of a metal-free phthalocyanine (Pc)-based discotic liquid crystal (DLC) using potentiodynamic and electrochemical impedance parameters. The phthalocyanine discotic liquid crystal (PcDLC) exhibited an excellent corrosion inhibition with a maximum inhibition efficiency of 89.61%. This superior ability was attributed to the strong adsorption of PcDLC on to the surface of mild steel as confirmed from the potentiodynamic polarisation data that fit into the cathodic inhibitor category. The protective layer of inhibitors generated on the MS surface was examined using scanning electron microscopy (SEM) and FTIR. The density function theory (DFT) approach was used to investigate the relationship between molecular structures and inhibitory efficacy, which indicated a strong interaction between the inhibitor and the surface iron atoms.