Carbon aerogels and xerogels
The aqueous polycondensation of resorcinol with formaldehyde proceeds through a sol-gel transition and results in the formation of highly crosslinked, transparent gels. If the solvent is simply evaporated from the pores of these gels, large capillary forces are exerted and a collapsed structure known as a xerogel is formed. In order to preserve the gel skeleton and minimize shrinkage, the aforementioned solvent or its substitute must be removed under supercritical conditions. The microporous material that results from this operation is known as an aerogel. Because resorcinol-formaldehyde aerogels and xerogels consist of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths. The resultant porous materials are black in color and no longer transparent, yet they retain the ultrafine cell size (< 50 nm), high surface area (600--800 m[sup 2]/g), and the interconnected particle morphology of their organic precursors. The thermal, acoustic, mechanical, and electrical properties of carbon aerogels/xerogels primarily depend upon polymerization conditions and pyrolysis temperature. In this paper, the chemistry-structure-property relationships of these unique materials will be discussed in detail.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6668983
- Report Number(s):
- UCRL-JC-108830; CONF-920402-67; ON: DE93009248
- Resource Relation:
- Conference: 1992 Material Research Society (MRS) spring meeting, San Francisco, CA (United States), 27 Apr - 2 May 1992
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON
FOAMS
PHYSICAL PROPERTIES
PRODUCTION
POROUS MATERIALS
FORMALDEHYDE
POROSITY
PRECURSOR
PYROLYSIS
RESORCINOL
ALDEHYDES
AROMATICS
CHEMICAL REACTIONS
COLLOIDS
DECOMPOSITION
DEVELOPERS
DISPERSIONS
ELEMENTS
HYDROXY COMPOUNDS
MATERIALS
NONMETALS
ORGANIC COMPOUNDS
PHENOLS
POLYPHENOLS
THERMOCHEMICAL PROCESSES
360601* - Other Materials- Preparation & Manufacture
360602 - Other Materials- Structure & Phase Studies
360606 - Other Materials- Physical Properties- (1992-)