title: Systematic studies of tannin-formaldehyde aerogels: preparation and properties.
abstract: Gelation of tannin-formaldehyde (TF) solutions was systematically investigated by changing pH and concentration of TF resin in water. In this way we constructed the TF phase diagram, from which chemical hydrogels could be described, and also synthesized thermoreversible tannin-based hydrogels. Conditions of non-gelation were also determined. Hydrogels were dried in supercritical CO2, leading to a broad range of TF aerogels. The latter were investigated for volume shrinkage, total porosity, micro-, meso- and macropore volumes, Brunauer-Emmett-Teller (BET) surface area, microscopic texture, mechanical and thermal properties. All these properties are discussed in relation to each other, leading to an accurate and self-consistent description of these bioresource-based highly porous materials. The conditions for obtaining the highest BET surface area or mesopore volume were determined and explained in relation to the preparation conditions. The highest BET surface area, 880 m2g-1, is remarkably high for organic aerogels derived from a natural resource.
authors.affiliation: Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France; Institut Jean Lamour-UMR CNRS 7198, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France.
authors.forename: Gisele
authors.initials: G
authors.lastname: Amaral-Labat
authors.affiliation: Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France; Institut Jean Lamour-UMR CNRS 7198, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Szczurek
authors.affiliation: Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France; Institut Jean Lamour-UMR CNRS 7198, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Fierro
authors.affiliation: Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France; LERMAB-EA 4370, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pizzi
authors.affiliation: Université de Lorraine, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France; Institut Jean Lamour-UMR CNRS 7198, ENSTIB, 27 rue Philippe Séguin, BP 1041, F-88051 Épinal Cedex 9, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Celzard
keywords: 10.01; 10.13; 20.09; aerogel; mechanical strength; porosity; surface area; tannin; thermal conductivity