Current states and future challenges of multifunctional flame-retardant polyurethane coatings

Polyurethane (PU) coatings are widely utilized in fields such as construction, electronics, transportation, and aerospace due to their excellent mechanical properties, resistance to chemical corrosion, and tunable molecular structure. However, their inherent flammability significantly restricts their application in environments with high fire safety requirements. Moreover, single-functionality is no longer sufficient to meet the demands of complex application environments. In recent years, researchers have developed multifunctional flame-retardant PU coatings that combine flame retardancy with additional functionalities, such as corrosion resistance, self-healing, and hydrophobicity, through the application of nanocomposites, surface modification techniques, and synergistic flame-retardant systems. This paper systematically reviews the flame-retardant mechanisms and functional design strategies of advanced polyurethane coatings, with the aim of providing valuable references for the design and development of next-generation high-performance flame-retardant materials.