Nanocomposite based ceramicizable functional coating with simultaneous flame retardancy and UV resistance for wood building material protection

Epoxy resin coatings are widely applied to wood structures and wood product protection. Therefore, the development of epoxy resin nanocomposites with high flame retardancy and UV resistance is of great significance for their widespread application. In this study, Nanocomposite based functional coating was prepared by introducing nanoparticle carbon nitride (g-C₃N₄), aluminum phytate (PA-Al), and nanoparticle tetramethylammonium caged polysilsesquioxanes (POSS) to create a hybrid covering of organic and inorganic materials. The coating effectively protects wood from flame damage by forming a ceramic like structure carbon layer of P-O-Si when exposed to flames. Results showed that epoxy coatings with PA-Al, g-C₃N₄ and POSS constituents achieved UL-94 V-0 rating. The limiting oxygen index (LOI) was 27.4 %, while THR and HRR values were reduced by 81.9 % and 84.3 %, respectively. Since g-C₃N₄ had exhibited a strong absorption peak in the ultraviolet (UV) region, the epoxy resin (EP) coating could achieve a blocking rate of 78.41 % and 84.16 % for the ultraviolet A (UVA) and ultraviolet B (UVB) bands, respectively. Meanwhile, the hardness and adhesion of EP coating were as high as 4 H and 5B. Thus, present work provides an optional route for the preparation of nanocomposite UV-resistant and flame retardant epoxy coatings, which can be applied to sustainable wood structural products.