110th Anniversary: High Molecular Weight Chitin and Cellulose Hydrogels from Biomass in Ionic Liquids without Chemical Crosslinking

Cellulose, chitin, and composite 3D hydrogels and membranes were fabricated without any chemical modification from high molecular weight chitin and cellulose rich material (CRM) extracted from shrimp shell or pine wood, respectively, using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). The hydrogels were prepared by re-dissolution of the extracted biopolymers in the same IL, or in a one-pot process directly from a solution of the biomass after extraction, followed by molding/gelation (‘3D gels’) or casting (membranes), and then washing. For comparison, the preparation of gels was attempted using commercial microcrystalline cellulose or chitin. From all the sources, the regenerated CRM or chitin required significantly lower load. Hydrogels were also converted into aerogels by transforming to alcogels and then Sc-CO2 drying giving materials of low density, high porosity, favorable compressibility, high water uptake, and moderate antioxidant activity. Air-dried membranes were dense...