Tailoring an epoxy-polyurethane self-healing coating for anticorrosion performance

Marine corrosion is a critical threat to the world's maritime infrastructure. While conventional epoxy coatings are widely used for corrosion protection, their inherent brittleness, microcrack propagation and limited self-healing capabilities remain unresolved challenges. To address these issues, this study proposes a synergistic strategy integrating reactive diluents (1,4-butanediol diglyceryl ether), hydrogen bond and flexible polyurethane (PU) segments to develop an advanced self-healing hybrid resin. Molecular structure screening revealed that increased epoxy equivalent weight (EEW) directly improved self-healing efficiency by facilitating chain mobility. Systematic investigation of the epoxy resins with different epoxy equivalents have demonstrated its critical role in balancing crosslink density, mechanical properties and glass transition temperature. Crucially, a novel polyurea prepolymer was synthesized and incorporated into the epoxy matrix to form a semi-interpenetrating polymer network (semi-IPN), achieving simultaneous toughening and enhanced self-healing. Comprehensive characterization using FT-IR spectroscopy, confocal laser scanning microscopy (CLSM), 3D profilometry and electrochemical tests confirmed the structural integrity, morphology and performance of the hybrid resin. The optimized material exhibited exceptional mechanical strength, high corrosion resistance (|Z|_0.01Hz > 10⁹ Ω·cm²), and remarkable self-healing efficiency (>90 % recovery after thermal activation at 60 °C for 6 h). This work provides a transformative approach to the design of multifunctional epoxy coatings for marine applications, bridging the gap between durability and adaptive protection.