Période de stage : Février 2020-juin/juillet 2020

Encadrement : Guillaume Mériguet (équipe MEM) Anne-Laure Rollet, J. Sirieix-Plénet (équipe ELI)

A 3-year funding for a PhD position is associated to this project in PHENIX in 2020 (ANR Move Your Ion)

Description of the project

Ionic liquids are often called ‘designer solvents’ thanks to the wide range of accessible properties and the tuning afforded by the change of the nature of the constituent ions. The mixtures of ionic liquids with other ionic solutes open even newer and innovative opportunities but they are still far from being understood despite their potential use in the enhancement of the performance of battery electrolytes or the leaching/extraction processes in the recycling of valuable metals. In addition, from a more fundamental point of view, in the perspective of their incorporation into devices, the optimization of the structure- transport relationship according to their use has to be carried out. Only a detailed knowledge of the key ion-driven transport mechanisms and their scale-dependent efficiency will enable the user to design the constraints imposed by the structure to the selected ionic species. Ion transport is expected to correlate intimately to the morphology of self-organized ionic systems across a range of length-scales, typically from molecular to nano-, meso- and macroscales.

To investigate these complex systems, we intend to take profit from the many advantages of Nuclear Magnetic Resonance (NMR) and especially its dynamic methods, including diffusion and relaxation. This non-invasive and isotope-selective technique is a tool of choice to investigate the dynamics in ionic media. Combining multiple methods, an impressive timescale range from a few ns up to 1 s can be covered, accessing efficiently the different dynamic mechanisms at play in the system. The outline of this Master project is the following :

1. Investigation of the effect of mixing ions in bulk ionic liquids on their dynamics using the aforementioned NMR dynamic methods.
2. Investigation of ion dynamics in thermotropic ionic liquid crystals (TILCs). The patented TILCS will be provided by our partner SyMMES (CEA Grenoble) in the larger framework of the ANR project Move Your Ion (start date January 2020).

Specific techniques or methods

NMR spectroscopy (including diffusion coefficient determination by PFG-NMR) and relaxometry on the two devoted experimental platforms of Sorbonne University.

References

• M. Giesecke, G. Mériguet, F. Hallberg, Y. Fang, P. Stilbs, I. Furó, Ion association in aqueous and non- aqueous solutions probed by diffusion and electrophoretic NMR, Phys. Chem. Chem. Phys. 17 (2015) 3402– 3408.
• J.-P. Korb, Multiscale nuclear magnetic relaxation dispersion of complex liquids in bulk and confinement, Prog. Nucl. Magn. Reson. Spectrosc. 104 (2018) 12–55.
• A.-L. Rollet, C. Bessada, NMR Studies of Molten Salt and Room Temperature Ionic Liquids, Annu. Reports NMR Spectrosc. 78 (2013) 149–207.
• D. Kruk, M. Wojciechowski, Y.L. Verma, S.K. Chaurasia, R.K. Singh, Dynamical properties of EMIM-SCN confined in a SiO₂ matrix by means of ¹H NMR relaxometry, Phys. Chem. Chem. Phys. 19 (2017) 32605–32616.