Superelastic and thermal insulating multilayer organic-inorganic hybrid aerogel built from boron nitride nanoribbons and aramid nanofibers

Thermally insulating aramid nanofiber (ANF) aerogels enable a wide range of applications but are limited by their low mechanical elasticity. Efficient design of aerogels' components and microstructures is crucial yet remains highly challenging for effectively improving the flexibility of ANF aerogels. Here, for the first time, we report the incorporation of boron nitride nanoribbons (BNNRs) into ANF aerogel to form a multilayer BNNR/ANF hybrid aerogel, which is prepared by suspension mixing of BNNRs and ANFs followed by a vacuum-assisted and directional solidification process. Flexible BNNRs with a high aspect ratio are uniformly embedded in the ANF networks, giving the ANF aerogel an extremely high mechanical deformability (up to 60 % compressive strain), capable of retaining its elasticity even after 100 compression cycles or in liquid N2 (−196 °C). Moreover, the introduction of BNNRs does not reduce the thermal insulation capacity of ANF aerogels, while significantly improving their thermal stability and fire resistance. These excellent multifunctionality benefits from the synergistic effect of organic–inorganic components and the multilayer structure of aerogel. This work paves the avenue for developing next-generation elastic and thermal insulating materials with great potential for widespread applications.