Flexible and Compressible Nanostructure-Assembled Aramid Nanofiber/Silica Composites Aerogel.

The Applications of silica aerogel are limited due to its brittleness and low strength. As a result, it is essential to strengthen and toughen it. Organic nanofibers are one of the preferred reinforcement materials. In this work, we designed and fabricated flexible and compressible nanostructure-assembled aramid nanofiber/silica composites aerogel (ANF/SiO2 aerogel) to improve the mechanical strength and flexibility of silica aerogel without compromising thermal insulation properties. The aramid nanofiber/silica composite aerogels were prepared by immersing the aramid nanofiber wet gel into the silica sol for a certain period of time followed by freeze drying without solvent replacement. The surface modifier 3-aminopropyltriethoxysilane (APTES) was used as a coupling agent to form chemical linkage between the ANF fiber and silica gel. It was observed that APTES can effectively drive the silica sol to infuse into ANF hydrogel, promoting the assembly of silica gel onto the fiber surface and a uniform distribution in the network of ANF. The compressive resilience, thermal stability, and thermal insulation properties of the composite aerogels were evaluated by inducing the silica aerogel into the ANF network to form a protective layer on the fiber and change the pore structure in the ANF network.