Carbon-13 nuclear magnetic resonance study of mixed micelles. Variation of interchain distances and conformational equilibria
Observed /sup 13/C NMR chemical shift changes with respect to their single micelles upon mixed-micelle formation of potassium dodecanoate and short-chain potassium carboxylates (hexanoate up to and including decanoate) are described in all but one case to increasing distances between the apolar ends of the long amphiphile chains as compared with its single micelle. Only for dodecanoate-hexanoate micellar systems can a different conformational equilibrium of the dodecanoate chain not be excluded. Furthermore, recently observed solvent effects upon mixing of n-alkanes of different chain lengths are compared with both the decanoate and nonanoate chemical shift changes upon mixing with the dodecanoate amphiphiles. This leads to the conclusion that the former detergents are mainly subject to increased intermolecular chain packing. Observed effects for the octanoate and heptanoate are not as pronounced, and these surfactants should be considered as borderline cases, while the hexanoate undergoes conformational changes toward more extended forms. 46 references.
- OSTI ID:
- 5932223
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:13; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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CARBON 13
CARBON ISOTOPES
COLLOIDS
DISPERSIONS
EMULSIONS
EQUILIBRIUM
EVEN-ODD NUCLEI
FLUID INJECTION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MICELLAR SYSTEMS
MICROEMULSIONS
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
PHASE STUDIES
RESONANCE
STABLE ISOTOPES
SURFACTANTS
TESTING
THERMODYNAMICS
WATERFLOODING