A self-healing polyurethane-based composite coating with high strength and anti-corrosion properties for metal protection

The self-healing ability of the organic coating is of pivotal importance to restore its protection functionality in case of a coating defect to ensure durable performance under demanding corrosive conditions. In this work, a novel NIR-triggered self-healing anti-corrosion coating is fabricated by cross-linking the PU prepolymer with furan modified CeO2 via Diels-Alder (DA) bonds, which could effectively protect mild steel from corrosion upon damage. The synthesized nanoparticles and PU films were detailly characterized using a range of tools. The developed coating (PU-DA-d@CeNPs5) had excellent mechanical property (38.89 ± 0.52 MPa), notable adhesion performance (12 MPa), and also exhibited an impedance modulus at 0.01 Hz of 1.29 × 109 Ω cm2. The impedance modulus at 0.01 Hz can still exceed 107 Ω cm2 after 100 days of continuous immersion. In addition, the photothermal conversion ability of dopamine enables the coating to self-heal rapidly within 20 s under near-infrared light. The mechanical and corrosion protection of the coating before and after self-healing were virtually unaffected. This work will provide an effective strategy for the preparation of anti-corrosion polyurethane coating with excellent mechanical performance and high self-healing efficiency. •Mechanically robust composite coating can be used as an excellent metal protection layer.•CeO2-PU composite coating shows ideal self-healing performance depended on DA dynamic bonds under NIR.•The corrosion protection of PU-DA-d@CeNPs5 after self-healing is almost the same as original (above 109 Ω cm2).