Physical Chemistry

Design of Long-Term Stable Concentrated Colloidal Dispersions in Ionic Liquids up to 473 K


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%)

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