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Are Hydrotropes Distinct from Surfactants?
- Source :
- Langmuir. 27:12346-12353
- Publication Year :
- 2011
- Publisher :
- American Chemical Society (ACS), 2011.
-
Abstract
- The physicochemical properties of a homologous series of sodium p-n-alkylbenzoates have been investigated. The objective was to determine whether there is a clear transition point from hydrotropic to surfactant-like behavior with increasing alkyl chain length n, so as to shed clear light on the aggregation mechanism of so-called "hydrotropes". Electrical conductivity measurements were used for a first estimation of the critical aggregation concentrations (cac). As for classical surfactants, log(cac) depends on alkyl chain length n, but two branches of behavior were observed: one having a gradient typical of long chain fatty acid salts and the other with a more shallow dependence. Surface tension (γ) measurements of high purity aqueous solutions were used to generate limiting headgroup areas A(cac), which were in the range (40-50 Å(2)) being consistent with monolayer formation. Small-angle neutron scattering conclusively shows that the lower chain length homologues (classed as hydrotropes) exhibit sharp transitions in aggregation as a function of bulk concentration, typical of regular surfactants. As such, there is little to suggest from this study that hydrotropes differ in association behavior from regular surfactants.
- Subjects :
- chemistry.chemical_classification
Aqueous solution
Surfaces and Interfaces
Neutron scattering
Condensed Matter Physics
Surface tension
Homologous series
chemistry.chemical_compound
chemistry
Transition point
Monolayer
Electrochemistry
Physical chemistry
Organic chemistry
General Materials Science
Long chain fatty acid
Spectroscopy
Alkyl
Subjects
Details
- ISSN :
- 15205827 and 07437463
- Volume :
- 27
- Database :
- OpenAIRE
- Journal :
- Langmuir
- Accession number :
- edsair.doi.dedup.....faf8eeb68c1b9f94da49a659902ddd5d
- Full Text :
- https://doi.org/10.1021/la2025846