Phytic acid-based smart coatings for enhanced passive-active fire protection of wood

Wood is abundant and has a high specific strength, but its practical applications are limited by its susceptibility to fire. In this study, a novel preparation process was introduced, in which Cu²⁺-exchanged ZSM-5 molecular sieves were chelated with phytic acid via a dynamic hydrothermal method and then coated onto the wood surface. The composite material, Cu-Z-P@W, with passive-active fire protection properties, was successfully prepared. Thermal stability tests showed that, compared to unmodified wood, the residual carbon ratio of Cu-Z-P@W increased from 0.99 % to 35.10 %, demonstrating excellent thermal insulation properties. In vertical combustion UL-94 tests, Cu-Z-P@W achieved a V-0 rating, with a limiting oxygen index (LOI) of 37.1 %. Additionally, the time to ignition (TTI) was extended to 113 s, while the total heat release (THR) was reduced by 41.76 %. The composite also effectively adsorbs and oxidizes carbon monoxide generated during combustion, thereby reducing smoke toxicity and improving flame retardancy. Moreover, Cu-Z-P exhibits good thermoelectric properties, responding at a low temperature (180 ℃) in just 0.6 s and providing over 20 repetitions of real-time alarms for more than 3 min, demonstrating excellent overall performance. As a result, Cu-Z-P@W shows great potential for applications in furniture manufacturing, interior decoration, building materials, and other fields.