Biomimetic Nanocomposite Coatings With Flame Retardancy, Mechanical Strength, and Water Resistance via Physicochemical Dual Cross‐Linking

ABSTRACT Plant fiber materials are cost‐effective and widely used, but they face significant challenges related to flammability and safety, particularly in high‐temperature and dry environments. This study presents an innovative layered biomimetic strategy that employs a physical–chemical double‐crosslinking approach using low‐cost polyvinyl alcohol (PVA), montmorillonite (MMT), ammonium polyphosphate (APP), and boric acid (BA) to create high‐modulus flame‐retardant nanocomposite coatings. The layered insulation structure formed by MMT and PVA, along with the synergistic effect between APP and MMT, results in an impressive ultimate oxygen index of 39.6, allowing the treated plant fiber materials to withstand exposure to fire for 7 min without igniting. The nanocomposite coating features a layered cross‐linked structure, with physical cross‐linking between PVA and MMT, and chemical cross‐linking between PVA and BA. Additionally, organic modification methods enhance the contact area between MMT and PVA, achieving a tensile strength of 145.92 MPa. The formation of ester bonds through chemical cross‐linking also improves the hydrolysis resistance of the coating. These unique properties make the nanocomposite coatings suitable for applications in construction, home, and other fields, significantly enhancing the safety and durability of plant fiber materials.