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Nanofibrillar cellulose aerogels |
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| Authors: | Hao Jin Yoshiharu Nishiyama Masahisa Wada and Shigenori Kuga |
| Institution: | a Chemical Engineering College, East China University of Science and Technology, Shanghai 200237, PR China b Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi1-1-1,Bunkyo-ku, Tokyo 113-8657, Japan |
| Abstract: | Highly porous aerogels consisting of cellulose nanofibrils were prepared by dissolution/regeneration of cellulose in aq. calcium thiocyanate followed by regeneration and carefully controlled drying. The influence of drying method (regular freeze drying, rapid freeze drying, and solvent exchange drying) on resulting porosity was studied by electron microscopy and nitrogen adsorption. While regular freeze drying caused significant coalescence of microfibrillar units, solvent exchange drying gave highly porous aerogel composed of approx. 50 nm-wide cellulose microfibrils. Correspondingly, specific surface area of the solvent-exchange-dried aerogels ranged 160–190 m2/g, in contrast to 70–120 m2/g of regular freeze-dried materials. Rapid freeze technique using liquid nitrogen-cooled metal plate gave aerogel sheets with asymmetrical porosity, with the face contacted by copper having porous structure similar to those of solvent-exchange dried material. |
| Keywords: | Cellulose hydrogel/aerogel Freeze drying Solvent-exchange drying Surface area |
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