[SY-O3] Impact of ionic liquid ordering on their triborheological properties
The development of novel lubrication concepts is a multi-scale challenge that requires the correlation of nano- and meso-scale features, such as molecule structure and their ordering, with macro-scale properties such as observed friction. Ionic Liquids (ILs) are interesting lubricants that are shown to have a positive impact on friction reduction. A feature that plays an important role in their behaviour is the Coulombic interaction between ions leading to layering in the transverse direction to the sliding and to a near-wall solidification, as seen both experimentally [1] and numerically [2]. At the same time, in-plane crystalline structures are also formed [3, 4, 5].
In this contribution, we quantify the impact of the internal structure on the triborheological properties of ILs. More precisely, both structure factors and bond-orientational order parameters will be calculated on coarse grain MD models of ILs in order to describe the ion ordering and formation of crystalline structures under bulk and confined conditions. Then an attempt will be made to correlate the detected ordering with internal (ion shapes and sizes), external (wall structure, pressure and shearing velocity) and constitutive (e.g., coefficient of friction) system parameters. Through such quantification, we expect an improved understanding of the underlying physico-chemical mechanisms, guiding us towards the design of optimised tribological systems.
1. A. M. Smith, K. R. J. Lovelock, N. N. Gosvami, P. Licence, A. Dolan, T. Welton, and S. Perkin, J. Phys. Chem. Lett. 4, 378 (2013).
2. K. Gkagkas, and V. Ponnuchamy, Model. Simul. Mater. Sci. Eng. 25 (6), 064004 (2017).
3. K. Gkagkas, V. Ponnuchamy, M. Dašić, and I. Stanković, Tribol. Int. 113, 83 (2016).
4. R. Capozza, A. Vanossi, A. Benassi and E. Tosatti, J. Chem. Phys. 142, 064707 (2015).
5. O. Fajardo, F. Bresme, A. Kornyshev, and M. Urbakh, Sci. Reports 5, 7689 (2015).
In this contribution, we quantify the impact of the internal structure on the triborheological properties of ILs. More precisely, both structure factors and bond-orientational order parameters will be calculated on coarse grain MD models of ILs in order to describe the ion ordering and formation of crystalline structures under bulk and confined conditions. Then an attempt will be made to correlate the detected ordering with internal (ion shapes and sizes), external (wall structure, pressure and shearing velocity) and constitutive (e.g., coefficient of friction) system parameters. Through such quantification, we expect an improved understanding of the underlying physico-chemical mechanisms, guiding us towards the design of optimised tribological systems.
1. A. M. Smith, K. R. J. Lovelock, N. N. Gosvami, P. Licence, A. Dolan, T. Welton, and S. Perkin, J. Phys. Chem. Lett. 4, 378 (2013).
2. K. Gkagkas, and V. Ponnuchamy, Model. Simul. Mater. Sci. Eng. 25 (6), 064004 (2017).
3. K. Gkagkas, V. Ponnuchamy, M. Dašić, and I. Stanković, Tribol. Int. 113, 83 (2016).
4. R. Capozza, A. Vanossi, A. Benassi and E. Tosatti, J. Chem. Phys. 142, 064707 (2015).
5. O. Fajardo, F. Bresme, A. Kornyshev, and M. Urbakh, Sci. Reports 5, 7689 (2015).