Article (Scientific journals)
Preparation of low-density xerogels through additives to TEOS-based alcogels
Alié, Christelle; Pirard, René; Lecloux, A. J. et al.
1999In Journal of Non-Crystalline Solids, 246 (3), p. 216-228
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Abstract :
[en] A new process for preparing silica xerogels with similar textural properties to silica aerogels by drying under vacuum has been studied. The xerogels are produced by adding, before gelation, 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) to tetraethylorthosilicate (TEOS)-based alcogels, synthesised in a single base-catalysed (NH3) step. It is hypothesized that EDAS acts as a nucleation agent leading to silica particles with a hydrolysed EDAS core and a shell principally made of hydrolysed TEOS. The EDAS concentration and the basicity of the aqueous NH3 solution are important parameters influencing the resistance of the gel to drying stress. A decreasing EDAS/TEOS ratio or an increasing concentration of NH3 at constant EDAS content leads to less shrinkage during drying and so the final pore volume is larger. Gels prepared with a low EDAS/TEOS ratio (about 0.03) contain large particles (similar to 20 nm) due to the nucleation process by EDAS, thus the pores between those particles are also large and the drying stress is reduced. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Disciplines :
Materials science & engineering
Chemical engineering
Author, co-author :
Alié, Christelle ;  Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Chimie physique appliquée
Pirard, René ;  Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Chimie physique appliquée
Lecloux, A. J.
Pirard, Jean-Paul ;  Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Chimie physique appliquée
Language :
English
Title :
Preparation of low-density xerogels through additives to TEOS-based alcogels
Publication date :
1999
Journal title :
Journal of Non-Crystalline Solids
ISSN :
0022-3093
Publisher :
Elsevier Science, Amsterdam, Netherlands
Volume :
246
Issue :
3
Pages :
216-228
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
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