Surprisingly high, bulk liquid-like mobility of silica-confined ionic liquids

Ronald Göbel (1) , Peter Hesemann (2) , Jens Weber , Eléonore Möller (1) , Alwin Friedrich (1) , Sabine Beuermann (1) , Andreas Taubert (1, 3)

1 Institut für Chemie [Universität Potsdam] | Institute of Chemistry [University of Potsdam]
2 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 Max Planck Institute of Colloids and Interfaces

Mesoporous silica monoliths were prepared by the sol-gel technique and filled with 1-ethyl-3-methyl imidazolium [Emim]-X (X = dicyanamide [N(CN)2], ethyl sulfate [EtSO4], thiocyanate [SCN], and triflate [TfO]) ionic liquids (ILs) using a methanol-IL exchange technique. The structure and behavior of the ILs inside the silica monoliths were studied using X-ray scattering, nitrogen sorption, IR spectroscopy, solid-state NMR, and thermal analysis. DSC finds shifts in both the glass transition temperature and melting points (where applicable) of the ILs. Glass transition and melting occur well below room temperature. There is thus no conflict with the NMR and IR data, which show that the ILs are as mobile at room temperature as the bulk (not confined) ILs. The very narrow line widths of the NMR spectra suggest that the ILs in our materials have the highest mobility reported for confined ILs so far. As a result, our data suggest that it is possible to generate IL/silica hybrid materials (ionogels) with bulk-like properties of the IL. This could be interesting for applications in, e.g., the solar cell or membrane fields.

Domaines: Matériaux

Ronald Göbel, Peter Hesemann, Jens Weber, Eléonore Möller, Alwin Friedrich, et al.. Surprisingly high, bulk liquid-like mobility of silica-confined ionic liquids. Physical Chemistry Chemical Physics, 2009, 11, pp.3653 - 3662. ⟨10.1039/b821833a⟩. ⟨hal-00371073⟩