DOI: 10.1140/epje/i2002-10124-y
Synergistic effects in mixed wormlike micelles of dimeric and single-chain cationic surfactants at high ionic strength
C. Oelschlaeger1, E. Buhler2, G. Waton1 and S.J. Candau11 Laboratoire de Dynamique des Fluides Complexes, U.M.R. n° 7506, Université Louis Pasteur, C.N.R.S., 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France
2 Groupe de Dynamique des Phases Condensées, U.M.R. n° 5581, Université Montpellier 2, cc 26, 34095 Montpellier, Cedex 5, France
candau@fresnel.u-strasbg.fr
(Received 18 November 2002 and Received in final form 18 March 2003 / Published online: 27 May 2003)
Abstract
The mixed micellization between the cationic gemini surfactant
[
(
)
2N
+(
) N
+
(
)
2
] and the cationic
cetyltrimethylammonium bromide (CTAB) in 150 mM KBr solutions has been
investigated. The variation of the cmc of the mixtures, measured by surface
tension experiments, with composition revealed synergism in micelle
formation. T-Jump and light scattering experiments performed in the vicinity
of the crossover volume fraction showed the existence of two micellar
populations, possibly linear and toroidal micelles. Rheological and
dynamic light scattering experiments allowed to fully characterize the
linear viscoelasticity of the mixtures. These measurements revealed
synergistic gains in viscoelastic properties with a maximum of the
stress-relaxation time around the equimolar composition. These effects are
ascribed to a progressive intermicellar crosslinking resulting from a
continuous increase of the end-cap energy with the 12-2-12 content in the
mixture.
82.70.Uv - Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems, (hydrophilic and hydrophobic interactions).
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.
83.60.Bc - Linear viscoelasticity.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003