Dynamic and Structural Properties of Room-Temperature Ionic Liquids near Silica and Carbon Surfaces
S Li and KS Han and G Feng and EW Hagaman and L Vlcek and PT Cummings, LANGMUIR, 29, 9744-9749 (2013).
The dynamic and structural properties of a room. temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium-(trifluoromethanesulfonimide) (C(4)mimTf2N) confined in silica and carbon mesopores were investigated by molecular dynamics (MD) simulations and nuclear magnetic resonance (NMR) experiments. The complex interfacial microstructures of confined C(4)mim Tf2N are attributed to the distinctive surface features of the silica mesopore. The temperature-dependent diffusion coefficients of C(4)mimTf2N confined in the silica or carbon mesopore exhibit divergent behavior. The loading fraction (f = 1.0, 0.5, and 0.25) has a large effect on the magnitude of the diffusion coefficient in the silica pore and displays weaker temperature dependence as the loading fraction decreases. The diffusion coefficients of mesoporous carbon-confined C(4)mimTf2N are relatively insensitive to the loading faction and exhibit a temperature dependence that is similar to the bulk dependence at all loading levels. Such phenomena can be attributed to the unique surface heterogeneity, dissimilar interfacial microstructures, and interaction potential profile of RTILs near silica and carbon walls.
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