Aim of the proposed project is the investigation of solvent-solvent, solute-solvent and solute-solute interactions in mixtures of archetypal imidazolium-based ionic liquids (ILs) with polar liquids using dielectric relaxation spectroscopy (DRS). The common solvents ethanol, methanol, acetonitrile, dimethyl sulfoxide, propylene carbonate and water will serve as examples for polar compounds. The entire mixing range from the pure IL to dilute solutions will be studied. DRS is especially powerful in monitoring cooperative motions and in the detection of weak ion pairing. Therefore, special attention will be paid to the association and solvation of the ions constituting the IL as a function of the concentration and polarity of the added polar compound and of the structure of the IL. The projects aims at a quantitative description of the speciation pattern in such mixtures as a function of IL concentration. The second focus will be on the transition of the cooperative mixture dynamics from the behaviour typical for IL to that of ¿normal¿ electrolyte solutions. This transition is probably connected with the loss of many solvent properties which make IL interesting for technical applications and therefore of fundamental interest.
