Vesicles in ionic liquids.

The formation of vesicles from 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) in several room-temperature ionic liquids, namely, 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4), 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2), and N-benzylpyridinium bis(trifluoromethylsulfonyl)imide (BnPyNTf2), as well as in a water/BmimBF4 mixture, was investigated. In pure ionic liquids, observations by staining transmission electron microscopy demonstrated clearly the formation of spherical structures with diameters of 200–400 nm. The morphological characteristics of these vesicles in ionic liquids, in particular, the membrane thicknesses, were first investigated by small-angle neutron scattering measurements. The mean bilayer thickness was found to be ∼63 ± 1 A in a deuterated ionic liquid (BnPyNTf2-d). This value was similar to that observed in water. The effect of ILs on the modification of the phase physical propert...