Research On The Corrosion Inhibition Performance Of Functionalized Imidazole-based Polymers On Carbon Steel In Acidic Media

Due to good mechanical strength and low cost,carbon steel is widely used in various engineering and industrial applications,such as chemical industry,transportation,machinery,construction,etc.Carbon steel is inevitably subjected to pickling during the processing process,which usually results in severe metal corrosion and a large amount of metal being dissolved resulting in huge losses.The addition of organic inhibitors is a costeffective and easy-to-operate anticorrosive measure,because compared with traditional non-agent corrosion inhibitors,organic corrosion inhibitors do not cause environmental pollution and cause less harm to humans.They often form a protective film on the metal surface by physical or chemical means,thereby inhibiting metal corrosion.Studies have shown that compounds with heteroatoms such as oxygen(O),nitrogen(N),and sulfur(S)and ? electron structures can be used as good corrosion inhibitors.From the perspective of molecular design,a polymerizable imidazolyl amphoteric salt VIPS containing a sulfonic acid group is selected in this research.Its structure contains a polymerizable carbon-carbon double bond,and the polyampholyl salt PVIPS can be obtained by radical polymerization.Therefore,this study compared the effect of the amphoteric salt on the corrosion inhibition effect before and after polymerization.In addition,poly-amphoteric salts can be acidified to obtain poly-ionic liquids(PIL).Polyionic liquids can not only obtain good corrosion inhibition effects,but also overcome the leakage of ionic liquids(IL)during use and transportation after polymerization.Difficult to transfer and other issues.Based on the previous research,we redesigned the synthetic route,synthesized a series of polyionic liquids with different degrees of polymerization,and explored the relationship between the degree of polymerization and the corrosion inhibition rate.The specific contents of this study are as follows:1)The imidazolyl amphoteric salt and polyionic liquid were synthesized,and their structures were characterized by FT-IR and 1H NMR,which proved that the product was consistent with the target compound.2)The kinetic inhibition of 45 # steel in 0.5 M HCl medium by the amphoteric salts and polyionic liquids with different polymerization degrees was evaluated by means of potentiostatic polarization and electrochemical impedance spectroscopy.The results show that the corrosion inhibition effect of the amphoteric salt after polymerization is significantly better than that of the amphoteric salt monomer,and the corrosion inhibition rate can reach 97% at a concentration of 500 ppm.For polyionic liquids with different degrees of polymerization,the best corrosion inhibition performance is obtained when the polymerization degree is 21,and the highest corrosion inhibition rate can reach 92.67%.It can be seen that the corrosion inhibition rate and the polymerization degree are not simply positive(negative)correlation,and there is an optimal polymerization degree range for the polymer's corrosion inhibition effect.In this study,both amphoteric salts and polyionic liquid corrosion inhibitors conform to the Langmuir isothermal adsorption model.3)Molecular dynamics simulations show that VIPS is adsorbed on the surface of carbon steel in parallel,and most of the repeating units of PVIPS are parallel to the surface of carbon steel.This arrangement is beneficial to obtain greater coverage and thus better corrosion inhibition.In addition,due to the many adsorption sites in the PVIPS molecule,it has stronger adsorption capacity.