Synthesis of novel photosensitive polymers for the protection of mild steel from acid corrosion

Abstract

Novel photosensitive polymers, namely poly((E)-(1-(10-(4-(3-(biphenyl-4-yl)-3-oxoprop-1-enyl)phenoxy)pentyl)-1H-1,2,3-triazol-4-yl)methyl propionate) (BI-5), poly((E)-(1-(10-(4-(3-(biphenyl-4-yl)-3-oxoprop-1-enyl)phenoxy)hexyl)-1H-1,2,3-triazol-4-yl)methyl propionate) (BI-6) and poly((E)-(1-(10-(4-(3-(biphenyl-4-yl)-3-oxoprop-1-enyl)phenoxy)decyl)-1H-1,2,3-triazol-4-yl)methyl propionate) (BI-10), were synthesized and the structure of the products were confirmed by ¹H NMR, FT-IR and UV-Visible spectral analysis. The rate of photo-cross-linking was evaluated by UV-Visible spectroscopic technique and the results revealed the efficient cross linking behavior of the synthesized polymers. For the first time in literature, these photo-cross-linkable polymers were investigated as inhibitors against the corrosion of mild steel (MS) in 1.0 M hydrochloric acid solution (HCl) by means of Tafel polarization and electrochemical impedance measurements. The polymers showed higher activity even at very lower concentrations (5 to 15 ppm). Potentiodynamic polarization studies revealed the mixed-type inhibiting nature of the inhibitors. The adsorption of inhibitors on the MS surface obeys the Langmuir adsorption isotherm model. The standard free energy of adsorption (ΔG_ads) value confirmed that physisorption as well as chemisorption takes place on the MS surface. The protection of MS by inhibitors was further well supported by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) analysis.