Effect of mild nanoscopic confinement on the dynamics of ionic liquids*

Ionic liquids, i.e. molten salts without an additional solvent, are discussed as innovative solvents and electrolytes in chemical processing and electrochemistry. A thorough microscopic understanding of the structure and ionic transport processes is essential for tailored applications. In this contribution, we study the influence of ‘‘mild’’ nanoscopic confinement on the structure and diffusion properties of an ionic liquid, 1-ethyl-3- methylimidazolium acetate, using neutron and x-ray scattering techniques. The structure is analyzed by X-ray diffraction, while neutron backscattering spectroscopy is used for the study of the diffusion processes in these systems. Interpreting the diffusion processes in terms of a jump-diffusion model allowed us to deduce the confinement effects on the jump length and residence time, both increased at elevated temperatures in confinement. The applied ‘‘mild’’ confinement, which leaves room for 10–25 times the domain spacing, allows us to observe in great detail how the onset of domain distortion decelerates the dynamics.