Mesoscale ordering in binary aqueous solvents induced by ion size asymmetry.
Surprising weak assembly behavior has lately been found in binary aqueous solvents containing antagonistic salt. The underlying mechanism is still under debate, particularly the role of ion size asymmetry. Here we use small-angle X-ray scattering to study the effect of ion size asymmetry on the mesoscale ordering in a binary solvent composed of water and 2,6-dimethylpyridine with added symmetrical quaternary ammonium salt. By systematically elongating the hydrocarbon side-chain lengths, and hence developing cation-to-anion size asymmetry, we provide the first experimental evidence of a gradual build-up of the solvent's mesoscale ordering. These results are in qualitative agreement with model-independent theoretical predictions.
Department of Chemistry and Molecular Biology, University of Gothenburg, SE-41296 Gothenburg, Sweden. kim.nygard@chem.gu.se.
Monika
M
Witala
MAX IV Laboratory, Lund University, PO Box 118, SE-22100 Lund, Sweden.
Sebastian
S
Lages
Department of Chemistry and Molecular Biology, University of Gothenburg, SE-41296 Gothenburg, Sweden. kim.nygard@chem.gu.se.
Kim
K
Nygård