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DY: Fachverband Dynamik und Statistische Physik

DY 47: Complex Fluids and Soft Matter I (joint session DY/CPP)

DY 47.1: Vortrag

Donnerstag, 23. März 2017, 15:00–15:15, ZEU 160

All-Atom Molecular Dynamics Simulation of Ionic Liquid films on Silica Surface — •Tamisra Pal and Michael Vogel — Institut für Festkörperphysik,Technische Universität Darmstadt,Hochschulstraße 6 64289 Darmstadt , Germany

Room temperature ionic liquid (RTIL) films in confined geometries have been recognized for their significant interfacial properties in electrochemical and electronic devices. Depending on the hydrophobicity of the anions, we chose IL 1-butyl-3-methylimidazolium cation with hexafluorophosphate ([Bmim][PF6]) and tetrafluoroborate ([Bmim][BF4]) counterparts. Here, the dynamical and structural properties of these ILs confined between amorphous silica slabs have been investigated by all-atom molecular dynamics simulation studies at 300 K. Relative number densities of the ions are calculated near the surface, as well as in the middle of the slit. The more hydrophilic [BF4]- ions tend to stay closer to the slab wall than symmetric [PF6]-, whereas the [Bmim]+ ions always resides in the next layer forming a bi-layered arrangement from the wall. A preferred orientation has been observed for the cations with their methyl groups pointing towards the slab surface and butyl tail projected inwards. The middle of the slit displays more of a bulk behavior in terms of density and ion diffusivities. Spatially-resolved analyses of the mean square displacement (MSD) and incoherent intermediate scattering function (ISF) reveal very sluggish and heterogeneous dynamics of these ILs in the vicinity of the silica surface, which need to be considered when designing applications.