Aerogels from unaltered bacterial cellulose: application of scCO2 drying for the preparation of shaped, ultra-lightweight cellulosic aerogels.
Bacterial cellulose produced by the gram-negative bacterium Gluconacetobacter xylinum was found to be an excellent native starting material for preparing shaped ultra-lightweight cellulose aerogels. The procedure comprises thorough washing and sterilization of the aquogel, quantitative solvent exchange and subsequent drying with supercritical carbon dioxide at 40 degrees C and 100 bar. The average density of the obtained dry cellulose aerogels is only about 8 mg x cm(-3) which is comparable to the most lightweight silica aerogels and distinctly lower than all values for cellulosic aerogels obtained from plant cellulose so far. SEM, ESEM and nitrogen adsorption experiments at 77 K reveal an open-porous network structure that consists of a comparatively high percentage of large mesopores and smaller macropores.
Liebner
Falk
F
Institute of Organic Chemistry, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, A-1190 Vienna, Austria. falk.liebner@boku.ac.at
Haimer
Emmerich
E
Wendland
Martin
M
Neouze
Marie-Alexandra
MA
Schlufter
Kerstin
K
Miethe
Peter
P
Heinze
Thomas
T
Potthast
Antje
A
Rosenau
Thomas
T
D000327:Adsorption; D002245:Carbon Dioxide / Q000737:chemistry*; D002482:Cellulose / Q000096:biosynthesis / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry; D005782:Gels; D041822:Gluconacetobacter xylinus / Q000378:metabolism; D020100:Hydrogels / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000737:chemistry; D016062:Porosity; D013046:Specific Gravity; D014867:Water / Q000737:chemistry
D005782:Gels; D020100:Hydrogels; D014867:Water; D002245:Carbon Dioxide; D000431:Ethanol; D002482:Cellulose; D009584:Nitrogen