A Self-Healing Acrylic Coating with Local pH Adjustment and Chloride Trapping for Corrosion Protection of Steel Reinforcement

Steel reinforcement in concrete is prone to corrosion in a chloride environment. The resulting structural damage is the primary factor shortening the service life. Applying acrylic coatings to steel surfaces provides excellent protection. However, resin is vulnerable to alkali hydrolysis and physical damage under the harsh conditions in reinforced concrete. To address this issue, a composite coating of poly (methyl methacrylate-co-butyl acrylate-co-tannic acid-glycidyl methacrylate)/L-lysine-modified graphene oxide (PMBT/L-GO) is successfully prepared on the reinforcing steel. The active hydroxyl groups on tannic acid-glycidyl methacrylate (TA-GMA) enable the coating to neutralize OH - . The localized reduction in pH inhibits the saponification hydrolysis reaction of the resin. The incorporation of L-lysine-modified graphene oxide (L-GO) enhances barrier performance through a labyrinth effect. Modification of L-lysine creates active sites within the coating to capture Cl - . This potentially prevents the passive film formed on the surface of the reinforcing steel from being damaged. The combination of tannic acid (TA) and L-Lysine has a synergistic effect on corrosion inhibition, enhancing the anti-corrosion performance of the coating. Moreover, multi-level reversible hydrogen-bond networks are constructed in the coating matrix to achieve self-healing of micro-damage. The PMBT/L-GO coating exhibits a corrosion current density ( i corr ) of 3.84 × 10 -9 A·cm -2 in simulated concrete pore solution (SCPS). The low-frequency impedance modulus (|Z| f=0.01 Hz ) can recover to 2.94 × 10 8 Ω·cm 2 following 24 h of room-temperature self-healing after damage. This outstanding corrosion resistance and self-healing behavior indicates that it is a promising solution for protecting concrete reinforcement against corrosion.