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The liquid–liquid coexistence curves for the binary solutions of the room temperature ionic liquid (RTIL) 1-methyl-3-octylimidazolium tetrafluoroborate ([C 8 mim][BF 4 ]) in 1-pentanol and 1-hexanol were measured in the critical region. The critical exponent β and the critical amplitude B were deduced and the former was found to be consistent with the 3D-Ising value. The complete scaling theory was applied to describe the asymmetry of the diameters of the coexistence curves. Moreover, the dependences of the critical temperature, the critical mole fraction, the reduced critical temperature and the reduced critical density on the permittivity of alcohol for a series of binary solutions of RTIL in alcohols were discussed. [ABSTRACT FROM AUTHOR]

Mixedsurfactant solutions are studied to understand their synergisticeffects. Here we report the micellization properties of mixed surfactantsolutions of the gemini surfactant N,N′-bis(dimethyldodecyl)-1,2-ethanediammoniumdibromide (12–2–12)with the imidazolium ionic liquid 1-dodecyl-3-methylimidazolium bromide(C12mimBr) investigated by isothermal titration calorimetry(ITC), conductometry, fluorimetry, and dynamic light scattering (DLS).A two-parameter Margules model was successfully used to correlatethe cmc values and calculate the compositions and activity coefficientsof the two components in the mixed micelle phase for 12–2–12/C12mimBr aqueous solutions with different overall surfactantcompositions. The dissociation degree of counterion, the thermodynamicquantities of micellization, and the excess thermodynamic quantitiesfor the mixed micelle were calculated and discussed. The ITC experimentin the low overall surfactant composition region showed a second phasetransition. A thermodynamic model was proposed to explore phase behaviorsof two different types of micelle and their solution, which was furtherconfirmed by fluorescence and DLS studies. [ABSTRACT FROM AUTHOR]