Design of Thermoplastic and Few‐Layer Graphene Modified Epoxy Coatings With Semi‐Interpenetrating Polymer Networks for Hydrogen‐Bond Mediated Self‐Healing and Mechanical Performance Enhancement

ABSTRACT The growing demand for durable protective coatings in harsh environments has intensified interest in self‐healing epoxy systems, which autonomously repair damage and extend service life. However, conventional epoxy coatings lack intrinsic self‐healing functionality and are prone to damage. Thermoplastic modification, though effective in imparting self‐healing, often compromises the mechanical strength, limiting broader applicability. In this study, epoxy is modified with polycaprolactone (PCL) and polyethylene glycol (PEG), facilitating the formation of a semi‐interpenetrating network (semi‐IPN), enabling reversible hydrogen bonding and shape memory behavior. The coating demonstrates a healing efficiency of 87% after 1 h of heat treatment. To overcome the associated decline in stiffness, graphene synthesized by microwave expansion is introduced as a nanofiller. The optimized Epoxy/Polycaprolactone/Polyethylene glycol/Graphene composite system with 0.075 wt% graphene achieved improved tensile strength (48.9 MPa) and outstanding healing efficiency (~92% at 80°C for 1 h). Electrochemical Impedance spectroscopy further confirmed the self‐healing and anti‐corrosive performance, with an outstanding inhibition efficiency ( P i ) of 96.13%, charge transfer resistance of 8.73 × 10 5 Ω·cm 2 , and an impedance modulus of 8.2 × 10 8 Ω·cm 2 . These results establish the synergistic combination of thermoplastic modifiers and graphene as a promising route to design robust, multifunctional durable coatings with self‐healing and corrosion resistance.