Cellulose aerogels: Highly porous, ultra-lightweight materials

Abstract

Cellulosic aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. From Nmethylmorpholine-N-oxide (NMMO) solutions with cellulose contents between 1 and 12%, dimensionally stable cellulose bodies are produced, in which the solution structure of the cellulose is largely preserved and transferred into the solid state, the material having densities down to 0.05 g cm -3 and surface areas of up to 280 m 2 g -1 . In this study, several aspects of cellulosic aerogel production are communicated: the stabilization of the cellulose solutions against degradation reactions by agents suitable for later extraction and drying, a reliable extraction and drying procedure by supercritical carbon dioxide, the advantages of DMSO/NMMO in this procedure as a solvent/non-solvent pair, and some data on the physical properties of the materials.

Aerocellulose based on all‐cellulose composites

“…8 Several researchers have also reported successful production of nonderivatized cellulose aerogels (also referred to as aerocellulose). 6,[9][10][11][12][13][14] The preliminary step in creating an aerogel is to dissolve the cellulose. This is followed by precipitation in a suitable liquid media that acts to penetrate the structure and displace the solvent.…”

Cellulosic materials as biopolymers and supercritical CO2as a green process: chemistry and applications

“…By this method, materials of 0.06 g/cm 3 have been obtained. Liebner et al (2007Liebner et al ( , 2008 have reported the cellulose aerogels produced by scCO 2 drying of regenerated cellulose obtained by solvent exchange of a solution of cellulose in N-methylmorpholine-N-oxide; these materials showed surface areas of 172-284 m 2 /g. In another study, cellulose aerogels have been prepared by scCO 2 drying of the bacterial cellulose produced by the gram-negative bacterium Gluconacetobacter xylinum, resulting in highly porous dry cellulose aerogels showing a density of 8 mg/cm 3 (Figures 5 and 6;Haimer et al 2010, Liebner et al 2010.…”

Untersuchungen zur Regeneration und Trocknung bei der Herstellung von Cellulose‐Aerogelen

“…Abb. ); und zum anderen die Neutralisierung von CO 2 -Emissionen aus fossilen Energiequellen durch Vergrößerung der Biosphäre (Off-setting von CO 2 -Emissionen) [1].…”