Abstract

Simultaneously realizing active early fire-warning and passive flame-retardant functions of wood represents a pressing yet formidable global challenge for densely populated applications. A novel nano-clay intumescent flame retardant (IFR) HAM was successfully synthesized and incorporated into the microchannels and cell walls of wood substrate for effectively achieving robust mechanical properties, intelligent early fire-warning and prevention via a vacuum pressure impregnation and densification strategy. Typically, compared to pure wood, results showed that the bending and compressive strength of SmartPyro-FortisWood (SPFW) W-GO/HAM-20 were enhanced by 269.0% and 199.1% because of the construction of an internally nanohybrid densified structure via hydrogen bonding and π-π stacking interactions. Besides, by coupling the thermal reduction property of GO with the catalytic carbonization effects of HAM, W-GO/HAM-20 presented a supersensitive fire-warning response of ~1.3 s and ultralong alarm time of 77 min, which also enabled real-time current monitoring through a remote wireless system to activate multi-level alerts. Meanwhile, the limiting oxygen index (LOI) of W-GO/HAM-20 was significantly enhanced from 23.1% of pure wood to 44.2%, achieving a UL-94 V-0 level. Cone calorimetry test demonstrated a 46.6% reduction in peak smoke production rate (PSPR) and a 43.4% reduction in total smoke production (TSP) in the W-GO/HAM-20 relative to pure wood; the corresponding peak heat release rate (PHRR) and total heat release (THR) were also reduced by 29.6% and 39.0%, respectively. The multilevel synergistic flame-retardant and smoke-suppression mechanisms including heat/oxidative transfer obstruction, radical quenching, catalytic char formation and adsorptive decomposition were systematically elucidated in both gas and condensed phases. This work proposes an innovative design-fabrication strategy for multifunctional densified wood, which exhibits promising applications in sus