  Ionic liquids (ILs), also known as room-temperature molten salts, are
composed of pure ions with melting points usually below 100 degrees centigrade.
Because of their low volatility and vast amounts of species, ILs can serve as
"green solvents" and "designer solvents" to meet the requirements of various
applications by fine tuning their molecular structures. A good understanding of
the phase behaviors of ILs is certainly fundamentally important in terms of
their wide applications. This review intends to summarize the major conclusions
so far drawn on phase behaviors of ILs by computational, theoretical, and
experimental studies, illustrating the intrinsic relationship between their
dual ionic and organic nature and the crystalline phases, nanoscale segregation
liquid phase, ionic liquid crystal phases, as well as phase behaviors of their
mixture with small organic molecules.
