Heterostructured Graphene@Silica@Iron Phenylphosphinate for Fire‐Retardant, Strong, Thermally Conductive Yet Electrically Insulated Epoxy Nanocomposites

Abstract The portfolio of extraordinary fire retardancy, mechanical properties, dielectric/electric insulating performances, and thermal conductivity (λ) is essential for the practical applications of epoxy resin (EP) in high‐end industries. To date, it remains a great challenge to achieve such a performanceportfolio in EP due to their different and even mutually exclusive governing mechanisms. Herein, a multifunctional additive (G@SiO 2 @FeHP) is fabricated by in situ immobilization of silica (SiO 2 ) and iron phenylphosphinate (FeHP) onto the graphene (G) surface. Benefiting from the synergistic effect of G, SiO 2 and FeHP, the addition of 1.0 wt% G@SiO 2 @FeHP enables EP to achieve a vertical burning (UL‐94) V‐0 rating and a limiting oxygen index (LOI) of 30.5%. Besides, both heat release and smoke generation of as‐prepared EP nanocomposite are significantly suppressed due to the condensed‐phase function of G@SiO 2 @FeHP. Adding 1.0 wt% G@SiO 2 @FeHP also brings about 44.5%, 61.1%, and 42.3% enhancements in the tensile strength, tensile modulus, and impact strength of EP nanocomposite. Moreover, the EP nanocomposite exhibits well‐preserved dielectric and electric insulating properties and significantly enhanced λ . This work provides an integrated strategy for the development of multifunctional EP materials, thus facilitating their high‐performance applications.