Self-aggregate nanoscale copolymer of new synthesized compounds efficiently protecting copper corrosion in sulfuric acid solution

Abstract

Unilateral and bilateral substitution compounds named 4-((1H-indol-3-yl)methyl)phenol (IMP) and 4-(di(1H-indol-3-yl)methyl)phenol (DIMP) have been synthesized, basing on the preparation of copolymer. The morphology images show that the target molecules can aggregate and organize spontaneously in sulfuric acid solution at room temperature with the formation of spherical or ellipsoidal nano-copolymers. And the effects of structure of synthesized compounds on copper corrosion inhibition are analyzed. The XPS study indicates that the organization of copolymers on the copper surface is mainly forced by the chemical adsorption, that is, the N heteroatom contained lone pair electrons can give electrons to the vacant orbital of copper as a result of forming the adsorbed protection layer. The electrochemical tests suggest that target copolymers show excellent corrosion protection performance for copper in 0.5 M H2SO4 solution. The corrosion inhibition efficiency of DIMP aggregates (DIMPs, 99.3%) is better than the IMP aggregates (IMPs, 97.5%) at the concentration of 2 mM, which is attributed to the effects of the stronger intermolecular hydrogen bonding and π-π intermolecular forces of bilateral donated groups of DIMPs than that of IMPs. In addition, the improvement of hydrophobicity of target-modification is also in favor of inhibition performance. Theoretical calculations further reveal the active sites of inhibitor molecules and their adsorption configurations on the copper surface.