Flexible Aerogel Materials: A Review on Revolutionary Flexibility Strategies and the Multifunctional Applications

The design and preparation of flexible aerogel materials with high deformability and versatility have become an emerging research topic in the aerogel fields, as the brittle nature of traditional aerogels severely affects their safety and reliability in use. Herein, we review the preparation methods and properties of flexible aerogels and summarize the various controlling and design methods of aerogels to overcome the fragility caused by high porosity and nanoporous network structure. The mechanical flexibility of aerogels can be revolutionarily improved by monomer regulation, nanofiber assembly, structural design and controlling, and constructing of aerogel composites, which can greatly broaden the multifunctionality and practical application prospects. The design and construction criterion of aerogel flexibility is summarized: constructing a flexible and deformable microstructure in an aerogel matrix. Besides, the derived multifunctional applications in the fields of flexible thermal insulation (flexible thermal protection at extreme temperatures), flexible wearable electronics (flexible sensors, flexible electrodes, electromagnetic shielding, and wave absorption), and environmental protection (oil/water separation and air filtration) are summarized. Furthermore, the future development prospects and challenges of flexible aerogel materials are also summarized. This review will provide a comprehensive research basis and guidance for the structural design, fabrication methods, and potential applications of flexible aerogels.