A review on polysaccharide based aerogel synthesis and their applications

Aerogels are highly porous solid materials with density even less than air. Various materials such as cellulose, chitosan, titanium oxide, chitin, pectin, silica oxide, starch, carrageenan, and mucilage have been used till date to synthesize the aerogels. However, these aerogels can be brittle, toxic, non-biodegradable, and can add environmental load on degradation. Since last few decades, polysaccharide-based aerogels owing to their various advantageous properties such as high porosity, biocompatibility, biodegradability, and ease of tailoring, have gained more interest. Similar to inorganic-based aerogels, organic or polysaccharide-based aerogels are also being synthesized using the sol-gel technique. However, based on the drying process used, a gel can be transformed into xerogel, cryogel, and xerogel. This article focuses on the synthesis of aerogels using sol-gel process and the classification of gels on the basis of drying processes adopted such as supercritical carbon dioxide (SCO2) drying, freeze-drying, and ambient pressure drying. Various sources of polysaccharides that can be extracted from plants, animals, and microorganisms have been mentioned in detailed. Additionally, applications of aerogels such as medical, air filtration, packaging thermal insulators, and construction have also been discussed.