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Stage de M2 : Dispersions of nanoparticles in ionic liquids

par Emilie Secret - 17 novembre 2020

Ionic liquids are a new family of solvents only made of cations and anions. Many of their properties, like high thermal stability, low vapour pressure, large electrochemical window, electrical conductivity, wetting properties, solubilization properties, refractive index...can be tuned and adapted changing the design of the ions. These liquids are of interest for numerous fields of applications and in particular for the production of green energy. The dispersion of nanoparticles (NPs) in these new media can further improve the system’s properties and provides new possibilities of applications [1].

However the dispersions of NPs is a challenge in these non-conventional solvents. Indeed, since these solvents appear as very concentrated electrolytes, the classical DLVO theory cannot be used and the interparticular forces actually responsible for colloidal stability are to be elucidated. In the last years, we explored the dispersion of magnetic iron oxide NPs first in ethylammonium nitrate (EAN) [2] then in numerous other ionic liquids [3]. These works showed that long lasting stable dispersions can be obtained depending on the details of the interface between the solid NP and the liquid which appeared crucial. In particular, the value of the charge of the NP, the nature of the counterions of these charged NP and the molecules close to the interface govern the nanostructure obtained : dispersions of single NPs, aggregates, flocculation.

In this context, the aim of the internship is to develop the dispersion of other types of NPs. In a first step, we will focus on titanium oxide. We will vary the size of the particles and the nature of the surface coating that controls colloidal aggregation. The ionic liquids will be chosen for their potential applications.

[1] Z. He and P. Alexandridis, « Ionic liquid and nanoparticle hybrid systems : Emerging applications » Adv. Colloid Interface Sci., 2017, 244, 54–70, doi : 10.1016/j.cis.2016.08.004 [2] M. Mamusa, J. Sirieix-Plénet, R. Perzynski, F. Cousin, E. Dubois, et V. Peyre, « Concentrated assemblies of magnetic nanoparticles in ionic liquids », Faraday Discuss., vol. 181, p. 193-209, 2015, doi : 10.1039/C5FD00019J [3] J. C. Riedl et al., « Colloidal dispersions of oxide nanoparticles in ionic liquids : elucidating the key parameters », Nanoscale Advances, p. 15, 2020, doi : 10.1039/C9NA00564A

Internship period : February – June 2021. Dates can be adapted around this period. The internship will be adapted to the sanitary conditions and home working will be implemented if necessary.

Specific techniques or methods : Dynamic Light Scattering (DLS), Thermogravimetric analysis (TGA), Ultracentrifugation, UV/IR spectroscopy, Karl Fisher titrations for water, Small Angle X-Ray Scattering (outside PHENIX)