Ionic liquids: Simple or complex electrolytes?

Abstract

Ionic liquids belong to the most investigated systems in the recent years and this field is still significantly growing with an increased focus on developing ionic liquids for specific applications, along with fundamental research. In the present featured paper the similarity and differences between common, “classical” electrolytes and common surfactants and ionic liquids along with the surface-active ionic liquids are discussed in order to stress their significance and point out on their weak points. A short survey of the literature data reveals namely that ionic liquids in solutions behave like “classical” electrolytes and can be described by existing models in the range of their validity. There is still a lack of models describing well the concentrated electrolyte solutions and here ionic liquids, less limited by solubility as common electrolytes, can serve as model systems. The micellization of surface-active ionic liquids in aqueous solutions can be described in the same way as for common surfactants, but surface-active ionic liquids offer more possibilities to study specific ion and isomer effects. They are also quite promising systems to study the aggregation processes in non-aqueous solutions.