Truss-inspired ultra-high strength, fire-safe, and thermal insulating double-crosslinked wood aerogels

Abstract

• A multifunctional wood aerogel (TSP@Ca) is prepared by a dual cross-linking strategy; • TSP@Ca aerogel features superior mechanical and flame-retardant performance; • TSP@Ca aerogel exerts gas- and condensed-phase flame-retardant effects during combustion; • The thermal conductivity of TSP@Ca is 46.4% lower than that of wood. Bio-based wood aerogel is one of the most promising materials to replace traditional petrochemical-based insulation materials. However, the flammability and poor mechanical strength of bio-based wood aerogels limit their applications in emerging fields. Inspired by a truss-supporting system, this study prepared a multifunctional bio-based cross-linked wood aerogel (TSP@Ca) by a dual hydrogen-ionic bonding strategy involving an oxidized wood cellulose framework, sodium alginate, phytic acid (PA), and Ca 2+ . Finite element simulation and mechanical analysis indicated that the multi-point support structure, resembling a truss framework, formed in the oxidized wood template significantly improved the strength of TSP@Ca aerogel (9.99 MPa), with a 154.84% enhancement relative to that of oxidized delignified wood (TODW). The limiting oxygen index of TSP@Ca3 aerogel was as high as 43.3%, and it can extinguish immediately when the fire was removed. The introduction of PA and Ca 2+ promoted the dehydration, cross-linking, and charring of TSP@Ca aerogel, while the produced phosphorus-containing free radicals played an inhibitory role in the gas phase. Therefore, the peak of heat release rate of TSP@Ca aerogel was 80.66% lower than that of TODW, showing excellent fire safety. Benefiting from the complex heat conduction path and enhanced interface resistance, the thermal conductivity of TSP@Ca was 46.4% lower than that of TODW. The resulting aerogel combines ultra-high mechanical strength, excellent fire resistance, and thermal insulation, aligning with “green” development goals and offering broad application potential in construction, rail transport, and new energy sectors.

The authors' abstract, as published at the source. Journal of Material Science and Technology, 2025 · DOI ↗