Preparation of nanoporous cellulose foams from cellulose-ionic liquid solutions

Nanoporous cellulose foams have been successfully prepared by a procedure in three steps: (i) dissolving in a room temperature ionic liquid (1-butyl-3-methylimidazolium chloride); (ii) coagulation in water; (iii) rapid freeze drying using liquid N2. The results show that the foam had a 3D open fibrillar network structure with the specific surface area as high as 186.0 m2/g and a porosity of 99%. Moreover, the cellulose foam shows cellulose II crystalline structure. Cellulose concentration in hydrogel as well as drying methods influences upon the structure and pore size of cellulose foams.