Kinetics of the self‐assembly of gemini surfactants

A stopped‐flow technique combined with pulsed‐field‐gradient spin‐echo nuclear magnetic resonance (NMR) measurements was used to study the kinetics of exchange, size, and shapes in micellar systems of cationic surfactant dimers of the alkanediyl‐α‐ω‐bis(dodecyldimethylammonium bromide) type, with al...

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Bibliographic Details
Published in:Journal of surfactants and detergents 2004-07, Vol.7 (3), p.247-255
Main Authors: Groth, C., Nydén, M., Holmberg, K., Kanicky, J. R., Shah, D. O.
Format: Article
Language:English
Subjects:
Dimeric
gemini surfactants
Kinetics
kinetics of micellization
lifetime of micelles
Molecules
NMR
Nuclear magnetic resonance
self‐diffusion
slow relaxation time
stopped flow
Surfactants
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Summary:A stopped‐flow technique combined with pulsed‐field‐gradient spin‐echo nuclear magnetic resonance (NMR) measurements was used to study the kinetics of exchange, size, and shapes in micellar systems of cationic surfactant dimers of the alkanediyl‐α‐ω‐bis(dodecyldimethylammonium bromide) type, with alkanediyl being 1,2‐ethylene, 1,3‐propylene, and 1,4‐butylene. By measuring the slow relaxation time for micelles, τ2, the micelle lifetime as a function of spacer length was obtained and was further confirmed by micelle exchange measurements by NMR diffusometry. The micelle lifetimes for the gemini surfactants were found to be in orders of magnitude longer than for the corresponding conventional surfactants. All three cationic surfactant dimers showed an increase in micelle size in one direction, i.e., became prolates, as the concentration was increased. The growth of the micelles was most pronounced for the gemini surfactants with the shortest linker unit, i.e., ethylene.
ISSN:1097-3958
1558-9293
DOI:10.1007/s11743-004-0308-8