title: Synergistic effects in mixed wormlike micelles of dimeric and single-chain cationic surfactants at high ionic strength.
abstract: The mixed micellization between the cationic gemini surfactant [C12H25(CH3)2N+(C2H4)N+(CH3)2C12H25*2Br-] 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.
authors.affiliation: Laboratoire de Dynamique des Fluides Complexes, UMR n 7506, Université Louis Pasteur, CNRS, 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Oelschlaeger
authors.forename: E
authors.initials: E
authors.lastname: Buhler
authors.forename: G
authors.initials: G
authors.lastname: Waton
authors.forename: S J
authors.initials: SJ
authors.lastname: Candau
mesh_terms: D001665:Binding Sites; D002412:Cations / Q000737:chemistry; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D045424:Complex Mixtures / Q000737:chemistry*; D003198:Computer Simulation; D019281:Dimerization; D004548:Elasticity; D007473:Ion Channels / Q000737:chemistry*; D046911:Macromolecular Substances; D008823:Micelles; D008956:Models, Chemical; D008968:Molecular Conformation; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity
chemical_list: D002412:Cations; D002593:Cetrimonium Compounds; D003102:Colloids; D045424:Complex Mixtures; D007473:Ion Channels; D046911:Macromolecular Substances; D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C046112:didodecyldimethylammonium; D000077286:Cetrimonium