Aqueous Two-Phase Systems of the Aqueous Mixtures of Cationic–Anionic Surfactants

Stomatosomes, blastula vesicles and bilayer disks: Morphological richness of structures formed in dilute aqueous mixtures of a cationic and an anionic surfactant

“…Zhao and Xiao carefully studied the formation of two liquid aqueous phases in dilute mixtures of anionic and cationic surfactants [15]. For mixtures of DTEB and an excess SDS without salt they observed phase separation within a narrow concentration area from a total concentration of 0.05 to 0.1 M; higher concentrations were not explored.…”

“…What prompted us to undertake the present study was two issues: the nature of the two liquid phases that separate within a narrow composition region, and the evolution of perforated bilayer structures. With respect to the liquid-liquid phase separation, a surprising conclusion from the investigations by Zhao et al of the DTEB/SDS system [15][16][17] was that both phases contained appreciable amounts of aggregates formed from mixtures of the two surfactants, as evidenced by the surface tension and peculiar rheological properties. In mixtures of DTEB and sodium dodecanoate it was even reported that both phases contained vesicles.…”

“…An interesting liquid-liquid phase coexistence occurs in many systems within a narrow composition region, often starting within the vesicle lobe and extending to higher total surfactant concentrations. A well-studied example is SDS and dodecyltriethylammonium bromide, DTEB [15,16]. Both phases display a complex rheological behavior [17].…”

Interfacial tension in phase-separated aqueous cationic/anionic surfactant mixtures

“…According to literature [4], for some aqueous two-phase cationic/anionic surfactant systems, the phase separation phenomenon is likely due to the coexistence of different kinds of micelles, for example, Table 1 The compositions of the top and bottom phases in some ATPS-C (m G = 0. 10 [23].…”

“…When two oppositely charged ionic surfactants are mixed forming an aqueous solution at certain concentrations and molar ratios, phase separation may occur, one phase is concentrated in the ions of both surfactants and the other one is dilute. It is a kind of aqueous two-phase system [1][2][3][4][5][6][7].…”