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Kinetics of the self‐assembly of gemini surfactants
Author(s) -
Groth C.,
Nydén M.,
Holmberg K.,
Kanicky J. R.,
Shah D. O.
Publication year - 2004
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-004-0308-8
Subject(s) - micelle , chemistry , pulmonary surfactant , cationic polymerization , bromide , kinetics , ethylene oxide , relaxation (psychology) , proton nmr , polymer chemistry , organic chemistry , aqueous solution , copolymer , polymer , psychology , social psychology , biochemistry , physics , quantum mechanics
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, τ 2 , 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.