Chitosan aerogels

Chitosan is derived from chitin, the second most abundant biopolymer on earth and a critical component of the mushroom, insects and crustaceans. Chitosan is produced available in large quantities from waste shrimp and crab shells from food production. Chitosan differs from other polysaccharides because of its amino groups, which open up new applications and provide a highly reactive anchoring point for cross-linking [1]. In our group, we developed a new type of chitosan aerogels through the use of a non-toxic urea cross-linker [2]. These aerogels have excellent thermal and mechanical properties and, unique among biopolymer aerogels, can be produced by ambient pressure drying. In later work, we were able to prepare transparent chitosan aerogels with the same cross-linker [3].

We also use the chitosan system as a model system to investigate the sol-gel and aerogel production process of biopolymer aerogels in detail. In situ SAXS measurements on chitosan solutions, hydrogels, organogels and aerogels indicate that, contrary to the current paradigm, the supercritical CO2 drying process is not always an inert process, but the key structure formation step during chitosan aerogel production [4-5].
[1] Takeshita, Satoru, et al. "Chemistry of chitosan aerogels: three‐dimensional pore control for tailored applications." Angewandte Chemie International Edition 60.18 (2021): 9828-9851. [2] Guerrero-Alburquerque, Natalia, et al. "Strong, machinable, and insulating chitosan–urea aerogels: toward ambient pressure drying of biopolymer aerogel monoliths." ACS Applied Materials & Interfaces 12.19 (2020): 22037-22049. [3] Takeshita, Satoru, Shanyu Zhao, and Wim J. Malfait. "Transparent, aldehyde-free chitosan aerogel." Carbohydrate Polymers 251 (2021): 117089. [4] Takeshita, Satoru, et al. "Formation of nanofibrous structure in biopolymer aerogel during supercritical CO2 processing: The case of chitosan aerogel." Biomacromolecules 20.5 (2019): 2051-2057. [5] Takeshita, Satoru, et al. "Solvents, CO2 and biopolymers: Structure formation in chitosan aerogel." Carbohydrate Polymers 247 (2020): 116680.