Diallylammonium salts containing nitrogen, ethyl ester and sulfide, sulfoxide or sulfone motifs of amino acid residues of methionine polymer as green corrosion inhibitors

摘要

A series of new specialty diallylammonium salt as monomers containing trivalent nitrogen, ethyl ester and sulfide, sulfoxide and sulfone motifs of amino acid residues of methionine were synthesized in excellent yields using cyclopolymerization process. Under the influence of pH, the polyelectrolyte-zwitterions could then be converted into cationic, zwitterionic and zwitterionic/anionic polymers with tremendous scientific and technological interest. The polyelectrolytes were characterized by various spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (NMR) and thermal gravimetric analysis (TGA). The solution properties of these polymers were investigated by viscometric techniques. These polyelectrolytes possess dual type of structural character and it is the electrolytic portion of the structure that dictates the solubility and viscosity behavior of the polymers. Corrosion inhibition efficiency of these synthesized compounds on mild steel have been determined by gravimetric method, Tafel extrapolation, linear polarization method, and electrochemical impedance spectroscopy in acid media. Different adsorption isotherms were also explored to find the best fit, and the X-ray photoelectron spectroscopy (XPS) confirms that the inhibitor molecules form a film at the metal surface. The surface coverage data demonstrated that the inhibitor molecules undergo adsorption onto the metal surface. The plethora of pH-responsive polymers containing essential amino acid residues of methionine demonstrated superb corrosion inhibition behavior in arresting corrosion in oil and gas industries.