Ionic liquids nanoscale properties make them potentially excellent lubricants: as the ions interact strongly with oppositely charged surfaces, they resist 'squeeze out' as surfaces are compressed, meaning a lubricating film will remain in place up to higher forces than for a comparable molecular liquid. The lubricating properties of ionic liquids can be controlled by varying the molecular structure of the ions1-4 and by applying an electric potential to the sliding contact.3,5 In this work the lateral structure of the graphite ionic liquidinterface is elucidated using combined high resolution amplitude modulated atomic force microscopy (AFM) imaging combined with quantum mechanical simulations as a function of potential. AFM nanotriblogical measurements will be rationalised in light of the surface and near surface ionic liquid nanostructure, and the molecular structure of the ions, to elucidate energy dissipation pathways. As the composition of the ion layer in contact with the graphite substrate changes as the potential is varied (anion rich at positive potentials and cation rich at negative potentials) this means that the relative contribution to each ion to lubrication can be commented upon. The variation in shear force with changes in the structure of the ions will be described, which enables the most lubricating ion morphologies to be identified.References(1) Werzer, O.; Cranston, E. D.; Warr, G. G.; Atkin, R.; Rutland, M. W. Physical Chemistry Chemical Physics 2012 , 14, 5147.(2) Asencio, R.; Cranston, E. D.; Atkin, R.; Rutland, M. W. Langmuir 2012 , 28, 9967.(3) Li, H.; Rutland, M. W.; Atkin, R. Physical Chemistry Chemical Physics 2013 , 15, 14616.(4) Elbourne, A.; Sweeney, J.; Webber, G. B.; Wanless, E. J.; Warr, G. G.; Rutland, M. W.; Atkin, R. Chemical Communications 2013 , 49, 6797.(5)  Sweeney, J.; Hausen, F.; Hayes, R.; Webber, G. B.; Endres, F.; Rutland, M. W.; Bennewitz, R.; Atkin, R. Physical Review Letters 2012 , 109, 155502.

Effect of surface nanostructure and ion structure on the nanotribology of the graphite: Ionic liquid interface

248th National Meeting (2014)

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