Synthesis, characterization and corrosion protection property of terpolymers derived from poly(MAn-co-MMA) containing benzimidazole derivative as pendant group

In this study the potential of the terpolymer synthesized from poly(maleic anhydride-co-methyl methacrylate) and hydroxymethylbenzimidazole as corrosion protective coating for 60–40 brass was evaluated using dip coating technique. The copolymer, poly(maleic anhydride-co-methyl methacrylate) synthesized using free radical solution polymerization was reacted with different feed ratios of hydroxymethylbenzimidazole (HMBD) to obtain terpolymers containing maleic anhydride, MMA and mono benzimidazolylmethyl ester of maleic acid (MBMEMA) units. Both the copolymer and the terpolymers were characterized using FT-IR, 1H NMR and 13C NMR spectroscopy. The thermal stability of the polymers was studied using thermogravimetric analysis (TGA) and the molecular weight of the polymer was analyzed using gel permeation chromatography (GPC). The effect of different concentrations of MBMEMA in the polymer for corrosion protection of brass in 3.5% NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Effective corrosion protection was obtained when the mole fraction of MBMEMA was 0.24 in the terpolymer. The surface morphology of the polymer coated specimens was studied by scanning electron microscopy (SEM). Solution analysis was used to calculate the dezincification factor.

► Synthesis of poly(MAn-co-MMA-co-MBMEMA).
► Terpolymer coating enhances the corrosion protection of brass in sea water.
► Retards dezincification of brass.
► Suitable for open cooling water systems.