Micro-Rebar Architecture Enable Fire-Safety and Tough PVA/AG Aerogels

Modern lightweight polymers and aerogels are ubiquitous in construction, transport, and energy storage, yet high flammability and smoke toxicity persist. To address these limitations, we construct a strongly reinforced and interlocked network within a Poly(vinyl alcohol)/Agarose (PVA/AG) dual network, where tannic-acid (TA) modulated MIL-88B@hydroxyapatite (MH) is uniformly anchored and intimately integrated to the polymer pore walls via interfacial coassembly. At an ultralow loading of 2 wt %, this composite exhibits exceptional fire safety performance, with reductions of 42.26% in total heat release, 36.11% in peak heat release rate, 63.65% in total smoke release, and 23.81% in peak smoke production rate, compared to the pure PVA/AG aerogel. Analysis of the flame-retardant mechanism reveals a targeted multiphase synergy: Fe³⁺ from MIL-88B catalyzes char graphitization; hydroxyapatite (HAP) decomposes to a calcium-phosphate ceramic, coalescing with carbon into a compact protective layer; and TA acts as a radical scavenger in the gas phase. The homogeneous distribution of the components collectively suppresses heat and mass transport. This work demonstrates that the precise hybridization and interfacial integration of established components can achieve superior flame retardancy at minimal loading, providing a promising design strategy for safety-critical applications in aerospace, construction, and energy storage.