Advances in multiple reinforcement strategies and applications for silica aerogel

Aerogels offer outstanding characteristics such as lightweight, high porosity, large specific surface area, and low density. For silica aerogels, because of the particular network containing -Si-O-Si-, it has low thermal conductivity, excellent sound insulation and small index of refraction, as well as numerous applications in areas of aerospace, biomedical, construction industry and sensing. Although silica aerogel research is relatively established, as with other aerogels, the poor mechanical properties limit their practical application. At present, the disadvantages of aerogel can be mitigated by altering the preparation process or incorporating the improved mechanical properties of other materials. The modification of silica aerogel by polymers, inorganics, and fibers, as well as the application of silica aerogel composites, have been discussed in this review. All three methods can significantly improve the mechanical properties of aerogel. In addition, inorganic reinforcement has superior thermal qualities over polymer reinforcement due to the great heat resistance of inorganic materials. At last, we briefly outline the current challenges and limitations of adding complexes to enhance silica aerogels. A road map pointing towards a future direction in modified silica aerogel will be discussed.