Source:http://linkedlifedata.com/resource/pubmed/id/16852369
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
22
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| pubmed:dateCreated |
2006-7-20
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| pubmed:abstractText |
In this article, we report a detailed study of resorcinol-formaldehyde (RF) aerogels prepared under different processing conditions, [resorcinol]/[catalyst] (R/C) ratios in the starting sol-gel solutions, using continuous flow hyperpolarized (129)Xe NMR in combination with solid-state (13)C and two-dimensional wide-line separation (2D-WISE) NMR techniques. The degree of polymerization and the mobility of the cross-linking functional groups in RF aerogels are examined and correlated with the R/C ratios. The origin of different adsorption regions is evaluated using both coadsorption of chloroform and 2D EXSY (129)Xe NMR. A hierarchical set of Xe exchange processes in RF aerogels is found using 2D EXSY (129)Xe NMR. The exchange of Xe gas follows the sequence (from fastest to slowest): mesopores with free gas, gas in meso- and micropores, free gas with micropores, and, finally, among micropore sites. The volume-to-surface-area (V(g)/S) ratios for aerogels are measured for the first time without the use of geometric models. The V(g)/S parameter, which is related both to the geometry and the interconnectivity of the pore space, has been found to correlate strongly with the R/C ratio and exhibits an unusually large span: an increase in the R/C ratio from 50 to 500 results in about a 5-fold rise in V(g)/S.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Jun
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| pubmed:issn |
1520-6106
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
9
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| pubmed:volume |
109
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
11215-22
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| pubmed:year |
2005
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| pubmed:articleTitle |
Nuclear magnetic resonance studies of resorcinol-formaldehyde aerogels.
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| pubmed:affiliation |
Steacie Institute for Molecular Sciences, National Research Council, Ottawa, Ontario, Canada K1A 0R6.
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| pubmed:publicationType |
Journal Article
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