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

Haimer, Emmerich; Liebner, Falk; Rosenau, Thomas; Neouze, Marie Alexandra; Wendland, Martin

doi:10.1002/cite.200750497

Cited by 2 publications

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“…In principle, both derivatization (covalent reagent bonding) and coating (reagents are just physically attached) are suitable strategies for BCAG modification. Because of the fragile nature of BCAGs, techniques based on supercritical carbon dioxide (scCO 2 ) have to be applied for appropriate drying to largely avoid changes of the natural BC structure (Liebner et al 2010;Haimer et al 2008;Liebner et al 2009Liebner et al , 2007Liebner et al , 2008; Gavillon and Budtova 2008). Due to its intrinsically low viscosity and special dissolution properties, scCO 2 can be used as multi-functional medium for processing of (bacterial) cellulose aerogels: drying, chemical reactions, and solvent for impregnation or fixation of various substances within the porous material without altering the natural morphology (Liebner et al 2010;Russler et al 2011).…”

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confidence: 99%

AKD-Modification of bacterial cellulose aerogels in supercritical CO2

et al. 2012

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Different approaches towards hydrophobic modification of bacterial cellulose aerogels with the alkyl ketene dimer (AKD) reagent are presented. If AKD modification was performed in supercritical CO 2 , an unexpectedly high degree of loading was observed. About 15 % of the AKD was bound covalently to the cellulose matrix, while the other part consisted of re-extractable AKD-carbonate oligomers, which are novel chemical structures described for the first time. These oligomers contain up to six AKD and CO 2 moieties linked by enolcarbonate structures. The humidity uptake from environments with different relative humidity by samples equipped with up to 30 % AKD is strongly reduced, as expected due to the hydrophobization effect. Samples above 30 % AKD, and especially at very high loading between 100 and 250 %, showed the peculiar effect of increased humidity uptake which even exceeded the value of unmodified bacterial cellulose aerogels.

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