Title
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Non-ideality in systems containing inverted micelles of anionic surfactants in apolar solvents, corrections for vapour pressure osmometric data
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Author
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Abstract
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Small angle X-ray scattering (SAXS) and vapour pressure osmometry (VPO) are interesting methods in order to obtain, respectively, the number and weight average aggregation number of the inverted micelles of surfactants in apolar solvents. Both methods are however affected by non-ideal behaviour within the system, resulting in a difference between the observed and true aggregation numbers. Relations are proposed which allow to calculate nwtrue and nntrue from the observed values using the concept of the volume excluded by the inverted micelles. In the case of anionic surfactants in apolar solvents this quantity can experimentally be obtained from SAXS measurements as a function of concentration. The system di-iso-hexadecyl zinc sulfonate in isododecane is discussed. The weight and number average aggregation numbers are almost identical and equal to 1718 after correction for non-ideality. This confirms the idea that the large inverted micelles are characterized by a rather narrow size distribution function. The experimental value for the excluded volume agrees rather well with that predicted for a hard sphere ensemble occupying the same volume fraction. |
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Language
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English
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Source (journal)
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Bulletin de la Société chimique de Belgique. - Bruxelles, 1904 - 1944
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Publication
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Bruxelles
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Société chimique de Belgique
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1980
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ISSN
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0374-6585
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DOI
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10.1002/BSCB.19800890801
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Volume/pages
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89
:8
(1980)
, p. 579-588
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ISI
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A1980KM85800001
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Full text (Publisher's DOI)
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