Comparison of Hydrogels Prepared with Ionic-Liquid-Isolated vs Commercial Chitin and Cellulose

Abstract

Physical and/or covalently linked (chemical) hydrogels were prepared from chitin and cellulose extracted with ionic liquid from shrimp shells and wood biomass, respectively, and compared with hydrogels prepared from commercially available biopolymers, practical grade chitin, and microcrystalline cellulose. The highly porous aerogels were formed by initial dissolution of the biopolymers in NaOH/urea aqueous systems using freeze/thaw cycles, followed by thermal treatment (with or without epichlorohydrin as a cross-linker) and supercritical CO2 drying. The ionic-liquid-extracted cellulose pulp and chitin, as well as practical grade chitin could form both stable physical and chemical hydrogels, whereas biopolymers of lower apparent molecular weight such as microcrystalline cellulose required a covalent cross-linker for hydrogel formation and commercially available pure chitin was not suitable for the preparation of hydrogels of either type. Hydrogels prepared from the ionic-liquid-extracted biopolymers exhibi...