Cellulose aerogels from aqueous alkali hydroxide-urea solution

Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2 Their morphology, pore structure, and physical properties were characterized by scanning and transmission electron microscopy, X-ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected fibrils of about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400-500 m(2)g(-1)) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors.