Solubilization of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, in a surfactant-water system

The amphiphilic association structures were determined in the system; water , Laureth 4 (approximately C-12(EO)(4)), and the ionic liquid 1-butyl-3-met hylimidazolium hexafluorophosphate ([bmim][PF6]), using visual observation and small angle x-ray diffraction. The system showed a lamellar liquid crys tal solubilizing the ionic liquid ([bmim][PF6]) to a maximum of 15%, an iso tropic surfactant solution dissolving the ionic liquid to a maximum of 39%, an isotropic ionic liquid solution with less than 0.5% of water and surfac tant and finally, an aqueous solution with only traces of surfactant and io nic liquid. The small angle x-ray diffraction results showed the ionic liqu id to be solubilized into the lamellar liquid crystal without changing the dimensions of the amphiphile layer or the interlayer spacing dependence on the water content.