In-situ polymerization engineered anisotropic biomass fire-resistant aerogels: Triple-functional integration of thermal insulation, mechanical robustness, and fire-warning performance

Biomass aerogels have emerged as promising green building insulation materials owing to their unique porous structure and sustainability. Nevertheless, their practical applications are constrained by poor fire resistance and mechanical stability. In this study, lightweight biomass aerogels (CS) based on sodium carboxymethyl cellulose (CMC) and sodium alginate (SA) were constructed, and graphene oxide (GO) was further introduced to reinforce the framework (CSG). Subsequently, polyaniline (PANI) was coated on the surface of the aerogel as a conductive shell layer by in situ polymerization to form a core-shell aerogel (CSGP) with fire safety and intelligent fire warning capability. Benefiting from the multiple interactions between biomass components, GO, PANI and Ca²⁺, CSGP core-shell aerogel exhibits a hierarchical porous crosslinked network, and at the same time possesses higher compressive strength (8.36 MPa), thermal insulation property (31.36 mW/(m·K)) and water resistance (32 days) than CS and CSG aerogels. In fire simulation tests, CSGP aerogel displays excellent flame retardancy (limiting oxygen index up to 49%, peak heat release rate as low as 31.37 kW/m²), owing to the dense physical barrier created by the PANI/GO composite layer. Furthermore, leveraging thermal reduction behavior of GO coupled with charge transport enhancement of PANI enable an ultra-fast fire warning response (1.3 s), crucial for emergency evacuation. This work establishes an innovative strategy for the integrated multifunctional design of biomass aerogel for mechanics-fire protection-smart warning, while promoting their potential application in the field of intelligent buildings.