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DLS and SAXS investigations of organic gels and aerogels
- Source :
- Journal of Non-Crystalline Solids, Journal of Non-Crystalline Solids, Elsevier, 2001, 285 (1-3), pp.Pages 154-161. ⟨10.1016/S0022-3093(01)00447-1⟩
- Publication Year :
- 2001
- Publisher :
- Elsevier BV, 2001.
-
Abstract
- 6th International Symposium on Aerogels (ISA-6) Albuquerque, New Mexico, October 08-11, 2000; International audience; Recent investigations have shown that the structure of organic aerogels can be significantly modified by changing the precursors, the solvent and the nature of the catalyst involved in the sol-gel reaction. It is therefore highly desirable to investigate the sol-gel mechanism. For this purpose, dynamic light scattering (DLS) measurements have been performed at different stages of the reaction for base- or acid-catalyzed gelation of resorcinol-formaldehyde (RF) using water or acetone as solvents. The structure of aged gels was investigated by small-angle X-ray scattering (SAXS) and compared to that of the aerogels obtained after exchange of solvent by supercritical CO2 and drying of the aged gels. It is shown that acid-catalyzed gelation of RF in acetone can be described by percolation, which explains that this series of aerogels consists of mass fractal aggregates (Dm = 2.5). The partial collapse of this polymeric gel yielding colloidal particles in the aerogel can be attributed to deswelling in supercritical CO2. DLS indicates that gelation of RF with a base catalyst yields a colloidal gel whose structure remains practically unchanged in the aerogel, as shown by SAXS.
- Subjects :
- Gelation
X ray scattering
02 engineering and technology
010402 general chemistry
01 natural sciences
Catalysis
Acetone
Colloid
[SPI.ENERG]Engineering Sciences [physics]/domain_spi.energ
Dynamic light scattering
Formaldehyde
Sol-gels
Materials Chemistry
Organic chemistry
Drying
Sol-gel
Supercritical fluids
Chemistry
Small-angle X-ray scattering
Agglomeration
Percolation (solid state)
Light scattering
Water
Aerogel
021001 nanoscience & nanotechnology
Condensed Matter Physics
Supercritical fluid
0104 chemical sciences
Electronic, Optical and Magnetic Materials
Organic solvents
Solvent
Aging of materials
Carbon dioxide
Chemical engineering
Alcohols
Percolation
Ceramics and Composites
0210 nano-technology
Subjects
Details
- ISSN :
- 00223093
- Volume :
- 285
- Database :
- OpenAIRE
- Journal :
- Journal of Non-Crystalline Solids
- Accession number :
- edsair.doi.dedup.....55c0ba6e9fcb2bde64ac58f7e73cdd68