A comprehensive study of highly soluble cationic polyfluorene as a polymer anticorrosive coating: Anticorrosion mechanisms and performance evaluation.

When using HCl to remove oxidation from metal surfaces, there is a risk of significant corrosion to the metal substrate. As a common industrial practice, organic or polymer coatings in corrosive environments protect metals from corrosion by providing a barrier on the metal surface within the corrosive medium. However, the limited solubility of polymers in aqueous corrosive mediums restricts their effectiveness. Herein, a highly water-soluble polyfluorene derivative, Poly(9,9-bis{3′-[(N , N -dimethyl)- N -ethylammonium}-propyl]-2,7-fluorene dibromide) (PFDN-Br), was synthesized as a HCl corrosion inhibitor to solve the corrosion problem of Q235 steel. The protective performance of the synthesized coatings was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) curves. The results of electrochemical testing demonstrate that the addition of PFDN-Br significantly reduces the corrosion rate of mild steel compared to the results without PFDN-Br. The average inhibition efficiency is 92.7 %. Additionally, the results of PDP indicate that PFDN-Br acts as a mixed-type corrosion inhibitor, with its adsorption on the surface of carbon steel following the Langmuir adsorption isotherm model. Quantum chemistry calculations (QC) and molecular dynamics simulations (MD) were employed to investigate the interaction mechanism between PFDN-Br and the surface. The excellent inhibitory performance of PFDN-Br may be attributed to its high-density side chains. This study provides insights into the development of polymer coatings with high water solubility and superior corrosion resistance. • Synthesized a highly water-soluble cationic Polyfluorene PFDN-Br. • PFDN-Br coating protects metals from acid corrosion. • After 10 h of immersion, PFDN-Br maintains a corrosion inhibition rate of 93 %. • The adsorption mechanism of PFDN-Br was elucidated through theoretical calculations. [ABSTRACT FROM AUTHOR]