Studies on formation and percolation in ionic liquids/TX-100/water microemulsions

• Published in: Journal of molecular liquids 2014-11, Vol.199, p.552-558
• Main Authors: Łuczak, Justyna, Hupka, Jan
• Format: Article
• Language: English
• Subjects: Conductivity; Ionic liquids; Microemulsions; Percolation; Viscosity
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2014.08.028

Ternary microemulsion systems of H2O/Triton X-100/[BMIM][Tf2N], and H2O/Triton X-100/[BMIM][PF6] were prepared, compared and characterized for phase behavior for different water/surfactant ratios, at 25°C. It was found that a change of an anion structure in the ionic liquids determines the total monophasic area of the systems. A liquid crystalline mesophase was detected in H2O/Triton X-100/[BMIM][PF6]. The microemulsion domains were identified by means of conductivity, viscosity and dynamic light scattering measurements. An increase in water mass fraction resulted in an increase of electrical conductivity of both systems, however not as rapid as in typical microemulsion systems. The conductivity data were analyzed in terms of percolation theory, and it was revealed, that the theory may be adopted only partially. The variations of the dynamic viscosity of surfactant/IL mixtures, as a function of water mass fraction along the experimental dilution lines, differ significantly from typical solvent based microemulsions. The size of water/IL microemulsion droplets, measured by dynamic light scattering, is nearly independent on the content of water. •Ternary ionic liquids microemulsions of H2O/Triton X-100/[BMIM][Tf2N], and H2O/Triton X-100/[BMIM][PF6] are described.•The microemulsion region in [BMIM][Tf2N] phase diagram is larger than for [BMIM][PF6] system.•Conductivity and viscosity studies reveal the thresholds indicating structural transitions of the microemulsion systems.•The percolation theory may be adopted only partially to describe ionic liquid microemulsion systems.