Research Progress in Micronano Interface Coating Modification of Wood Porous Scaffolds for High-Value Utilization in Flame Retardancy and Acoustics

Natural wood possesses a hierarchically porous and anisotropic structure, which provides a foundation for functional utilization, but its flammability and hygroscopicity limit its applications. Conventional bulk impregnation modification involves introducing functional agents throughout the entire pore system. This approach can enhance performance, but inevitably leads to lumen occlusion and increased density. To address this trade-off, researchers have recently developed micronano coating strategies based on interfacial decoration rather than bulk deposition within the lumina. These strategies confine functional components to cell wall surfaces while preserving the natural porous scaffold. Two fabrication routes have been developed, namely liquid-phase methods and gas-phase methods, which differ in coating precision, penetration depth, and interfacial bonding. In flame retardancy, interfacial coatings act as physical barriers and promote chemical charring. Inorganic layers suppress oxygen diffusion and heat transfer, while phosphorus or nitrogen components catalyze cellulose dehydration. In acoustics, conformal coatings regulate pore wall roughness and acoustic impedance, enhancing viscous and thermal dissipation without blocking channels. Challenges for practical application include mass transfer limitations in large logs, conflicts between high-precision processes and industrial economics, and interfacial durability under service conditions. This narrative review summarizes fabrication strategies, flame-retardant mechanisms, and acoustic regulation principles, providing guidance for coating strategy selection and process optimization. It is noted that this review focuses on wood species with open, permeable pore structures suitable for functional modification, rather than species whose pores are occluded by heartwood extractives.