MXene–Soy Protein–Hydroxyapatite Fire-Retardant Hybrid Nanocomposite Coating for Wood Protection and Forest Fire Prevention

The development of environmentally friendly and highly effective fire-retardant coatings is essential for wood protection and forest fire prevention. Traditional flame retardants often rely on halogenated or phosphorus-based chemicals, which pose toxicity and environmental concerns. To address this, we introduce a novel soy protein–MXene–hydroxyapatite (SP-MXene-CHA) hybrid nanocomposite designed as a sustainable, sprayable coating to enhance fire resistance. This study proposes an application-driven approach to fire inhibition, utilizing practical and simplified evaluation methods. The composite was synthesized by integrating SP, MXene, and hydroxyapatite (HA) modified with caffeic acid (CA), forming a stable dispersion. Structural characterization using FTIR, XPS, EDX, TGA, and contact angle measurements confirmed the successful incorporation and physicochemical stability of all components. FE-SEM imaging demonstrated a uniform distribution on the wood surface. Fire-retardant performance was assessed at three concentrations (50, 100, and 150 mg in 5.0 mL), showing a dose-dependent reduction in the flame spread and burning rate. The treatment resulted in 8, 46, and 56% decreases in fire propagation compared to untreated wood, respectively. The optimal concentration (150 mg) also exhibited fire migration suppression and maintained partial fire resistance after two cycles of simulated rain, with 21 and 42% reductions in effectiveness after the first and second cycles, respectively. These findings highlight SP-MXene-CHA as a highly effective, sustainable alternative to conventional flame retardants, offering potential applications in fire-resistant coatings for construction materials and wildfire prevention.