Carbon aerogels, cryogels and xerogels: Influence of the drying method on the textural properties of porous carbon materials

Carbon materials with tailored texture can be obtained from drying and pyrolysis of resorcinol–formaldehyde gels. The pore texture of both dried and pyrolyzed material depends on the drying process. Several more or less expensive methods (supercritical drying, freeze-drying, evaporative drying) were...

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Bibliographic Details
Published in:	Carbon (New York) Vol. 43; no. 12; pp. 2481 - 2494
Main Authors:	Job, Nathalie, Théry, Alexandre, Pirard, René, Marien, José, Kocon, Laurent, Rouzaud, Jean-Noël, Béguin, François, Pirard, Jean-Paul
Format:	Journal Article Web Resource
Language:	English
Published:	Oxford Elsevier Ltd 01-10-2005 Elsevier Science
Subjects:	Carbon aerogels Carbon xerogels Chemical engineering Chemistry Colloidal gels. Colloidal sols Colloidal state and disperse state Cross-disciplinary physics: materials science; rheology Engineering, computing & technology Exact sciences and technology Fullerenes and related materials; diamonds, graphite General and physical chemistry Ingénierie chimique Ingénierie, informatique & technologie Materials science Materials science & engineering Physics Porous materials Science des matériaux & ingénierie Specific materials Texture Texture Carbon aerogels Carbon xerogels Aerogels Xerogel Carbon Porous materials Drying
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Summary:	Carbon materials with tailored texture can be obtained from drying and pyrolysis of resorcinol–formaldehyde gels. The pore texture of both dried and pyrolyzed material depends on the drying process. Several more or less expensive methods (supercritical drying, freeze-drying, evaporative drying) were tested in order to determine which process is the most suitable for the synthesis of a porous carbon with a definite texture. Supercritical drying leads to the highest pore volume and the widest texture range, but residual surface tensions and shrinkage are not avoided when the pore size is small or when the material density is low; this hampers to fix both the pore volume and the pore size easily. Monoliths are very difficult to obtain by freeze-drying, and the appearance of huge channels due to ice crystal growth at high dilution ratio hinders the fabrication of low density materials. Moreover, gels with small pores do not remain frozen throughout drying, which leads to surface tensions and shrinkage. Although generally replaced by more complicated techniques, evaporative drying is suitable when dense carbons are needed or when the only selection criterion is the pore size: all pore sizes are reachable, but this parameter is in this case strongly correlated to the pore volume.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 scopus-id:2-s2.0-23144451634
ISSN:	0008-6223 1873-3891 1873-3891
DOI:	10.1016/j.carbon.2005.04.031