<p><b>This work presents a novel and comprehensive approach to predict and understand the stabilisation mechanisms of dispersions of nanoparticles in ionic liquids which </b><b>is at present unpredictable. This opens up applications with new materials combining the properties of both nanoparticles and ionic liquids.</b></p>

<p><b>This work presents a novel and comprehensive approach to predict and understand the stabilisation mechanisms of dispersions of nanoparticles in ionic liquids which </b><b>is at present unpredictable. This opens up applications with new materials combining the properties of both nanoparticles and ionic liquids.</b></p>

<div> <div> <div> <p>The use of ionic liquid-based colloids at elevated temperatures is one of their most promising fields of application. However long term stability on the whole range of temperature is mandatory. First a detailed study on colloidal dispersions of iron oxide nanoparticles in EMIM TFSI is performed at room temperature in order to determine the best solid/liquid interface. The previously identified key parameters are tuned: the surface charge density and the nature of the counterions. Here a sulfonate based imidazolium ion is chosen. In a second step, the thermal stability of these nanoparticle dispersions is analysed on the short and long term up to 473 K (200◦C) combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA). Ionic liquid-based colloidal dispersions of iron oxide nanoparticles in EMIM TFSI stable in the long term can be obtained at least up to 473 K and nanoparticle concentrations of 12 vol% (≈30wt%) </p> </div> </div> </div>

Some of the most promising fields of application of ionic liquid-based colloids imply elevated temperatures. Their careful design and analysis is therefore essential. The system studied are iron oxide nanoparticles (NPs) dispersed in ethyl-methylimidazolium bistriflimide (EMIM TFSI). The key parameters of the solid-liquid interface, tuned at room temperature, are the surface charge density and the nature of the counterions. The thermal stability of these nanoparticle dispersions is then analysed on the short and long term up to 473 K. A multiscale analysis is performed combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA). With a careful choice of the species at the solid-liquid interface, ionic liquid-based colloidal dispersions of iron oxide NPs in EMIM TFSI stable over years at room temperature can be obtained, also stable at least over days up to 473 K and NPs concentrations up to 12 vol% (30 wt%).

Hypothesis: Some of the most promising fields of application of ionic liquid-based colloids imply elevated temperatures. Their careful design and analysis is therefore essential. We assume that tuning the structure of the nanoparticle-ionic liquid interface through its composition can ensure colloidal stability for a wide temperature range, from room temperature up to 473 K. Experiments:The system under study consists of iron oxide nanoparticles (NPs) dispersed in ethylmethylimidazolium bistriflimide (EMIM TFSI). The key parameters of the solid-liquid interface, tuned at room temperature, are the surface charge density and the nature of the counterions. The thermal stability of these nanoparticle dispersions is then analysed on the short and long term up to 473 K. A multiscale analysis is performed combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA).Findings: Following the proposed approach with a careful choice of the species at the solid-liquid interface, ionic liquid-based colloidal dispersions of iron oxide NPs in EMIM TFSI stable over years at room temperature can be obtained, also stable at least over days up to 473 K and NPs concentrations up to 12 vol% (˘30 wt%) thanks to few near-surface ionic layers.