Synthesis and anticorrosive application of biomimetic dopamine-based cationic polyelectrolytes derived from diallylammonium salts

Dopamine hydrochloride was converted to monomer N,N-diallyldopamine hydrochloride [(3,4-(HO)2C6H4CH2CH2NH+(CH2CH--CH2)2 Cl-] (I). Polymerization of monomer diallydimethylammonium chloride (II) gave homocyclopolymer III, while its copolymerization with 5-20 mol% I afforded copolymers IV. Likewise, II/SO2 copolymerization and I/II/SO2 terpolymerization gave respective alternate copolymer V and terpolymers VI. Copolymer IV (containing 20 mol% dopamine motifs) imparted excellent inhibitions of mild steel corrosion in 1 M HCl as well as synergistic inhibition in the presence of iodide ions in 15% HCl at 60 degrees C. Increasing mol% of dopamine motifs in IV resulted in increasing corrosion protection and demonstrated better efficiency than monomer II and its homopolymer III. Cationic polyelectrolyte IV has been shown to form polyelectrolyte complex/coacervate with three model anionic polyelectrolytes.

Automated summary

In this study, dopamine hydrochloride was successfully converted to monomer N,N-diallyldopamine hydrochloride and then polymerized to form homocyclopolymer and copolymer. The copolymer exhibited excellent corrosion inhibition properties, especially when iodide ions were present. The presence of dopamine motifs in the copolymer resulted in increasing corrosion protection.