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Ionic Liquids (ILs) are a subset of molten salts, distinguished by having melting points below 100 °C. Neutron diffraction measurements modelled with reverse Monte Carlo simulations will be used to show that ILs have a sponge-like (bicontinuous) nanostructure; IL cation alkyl chains and ionic groups are segregated into domains that percolate throughout the bulk liquid.1-3 A snapshot of the simulation box for ethylammonium nitrate (EAN, a protic IL) is shown in Figure 1 (left). Varying the structure of the ions changes way inter-ionic forces are expressed, which leads to changes in nanostructure. The effect of dissolved water, glycerol and octanol on bulk IL nanostructure will be examined.4,5
High resolution amplitude modulated atomic force microscope images (c.f. Figure 1) will be used to demonstrate how IL nanostructure changes at a solid surface with the ion structure, and the effect of dissolved solutes.6-8 A 20 nm x 20 nm topographic AM-AFM images of the 1-Ethyl-3-methylimidazolium bis(trifluoromethyl- sulfonyl) imide – graphite Stern layer is shown in Figure 1 (middle), with the position of the ions shown in the magnified area in Figure 1 (right). The effect of applying a potential to a conducting solid surface on the IL interfacial nanostructure will also be discussed with reference to nanolubrication.
References
(1) Atkin, R.; Warr, G. G. J. Phys. Chem. B 2008, 112, 4164.
(2) Hayes, R.; Imberti, S.; Warr, G. G.; Atkin, R. Physical Chemistry Chemical Physics 2011, 13, 3237.
(3) Hayes, R.; Imberti, S.; Warr, G. G.; Atkin, R. Angewandte Chemie International Edition 2013, 52, 4623.
(4) Hayes, R.; Imberti, S.; Warr, G. G.; Atkin, R. Angewandte Chemie International Edition 2012, 51, 7468.
(5) Murphy, T.; Hayes, R.; Imberti, S.; Warr, G. G.; Atkin, R. Physical Chemistry Chemical Physics 2014, 16, 13182.
(6) Elbourne, A.; Voitchovsky, K.; Warr, G. G.; Atkin, R. Chemical Science 2015, 6, 527.
(7) Page, A. J.; Elbourne, A.; Stefanovic, R.; Addicoat, M. A.; Warr, G. G.; Voitchovsky, K.; Atkin, R. Nanoscale 2014, 6, 8100.
(8) Elbourne, A.; McDonald, S.; Voïchovsky, K.; Endres, F.; Warr, G. G.; Atkin, R. ACS Nano 2015, 9, 7608.