Tim GROVES1, Susan PERKIN1
1University Of Oxford Chemistry Department, Oxford, United Kingdom
Ion dense fluids are vital in applications ranging from electrochemical energy storage and carbon capture, to catalysis and pharmaceutical synthesis; while ion dense media also occur naturally, in cytoplasm within cells, and in salt lakes and brine basins. However, these high concentration electrolyte systems remain relatively poorly understood in comparison with low ion density electrolytes. Several recent findings have shown that ion dense systems are capable of separating on the nano-scale into segregated domains, driven by hydrophobic forces. Such nano-structuring is well known in long-chain ionic liquids, but has also recently been observed in water-in-salt electrolytes. Here, we present surface force experiments probing the structure of ion dense electrolytes and mixtures, and measure the effect of dilution of long-chain ionic liquids with shorter chain ionic liquids on this nano-structure. These results will have consequences for the understanding of ion dense mixtures, and provide a pathway for the greater tuning of ionic liquid properties through mixing.