title: Thermophysical Properties of Homologous Tetracyanoborate-Based Ionic Liquids Using Experiments and Molecular Dynamics Simulations.
abstract: Thermophysical properties of low-viscosity ionic liquids (ILs) based on the tetracyanoborate ([B(CN)4]-) anion carrying a homologous series of 1-alkyl-3-methylimidazolium ([AMIM]+) cations [EMIM]+(ethyl), [BMIM]+(butyl), [HMIM]+(hexyl), [OMIM]+(octyl), and [DMIM]+(decyl) were investigated by experimental methods and molecular dynamics (MD) simulations at atmospheric pressure and various temperatures. Spectroscopic methods based on nuclear magnetic resonance and surface light scattering were applied to measure the ion self-diffusion coefficients and dynamic viscosity, respectively. In terms of MD simulations, a nonpolarizable molecular model for [EMIM][B(CN)4] developed by optimization to experimental data was transferred to the other homologous ILs. For the appropriate description of the inter- and intramolecular interactions, precise and approximate force fields (FFs) were tested regarding their transferability within the homologous IL series, aiming at reducing the computational effort in molecular simulations. It is shown that at comparable simulated and experimental densities, the calculated and measured data for viscosity and self-diffusion coefficients of the ILs agree well mostly within combined uncertainties, but deviate stronger for longer-chained ILs using an overly coarse FF model. For the [B(CN)4]--based ILs studied, a comparison with literature data, the influence of varying alkyl chain length in the cation on their structural and thermophysical properties, and a correlation between self-diffusivity and viscosity are discussed.
authors.affiliation: Department of Chemical and Biological Engineering (CBI) and Erlangen Graduate School in Advanced Optical Technologies (SAOT), University of Erlangen-Nuremberg , Paul-Gordan-Straße 6, 91052 Erlangen, Germany.
authors.forename: Thomas M
authors.identifier: 0000-0003-4917-3079
authors.initials: TM
authors.lastname: Koller
authors.affiliation: Departamento de Física Macromolecular, Instituto de Estructura de la Materia, CSIC, BIOPHYM , Serrano 113bis, 28006 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Ramos
authors.affiliation: Department of Chemical and Biological Engineering (CBI), Institute of Chemical Reaction Engineering, University of Erlangen-Nuremberg , Egerlandstraße 3, 91058 Erlangen, Germany.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Schulz
authors.affiliation: National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Molecular Thermodynamics and Modelling of Materials Laboratory ,15310 Aghia Paraskevi Attikis, GR, Greece.|Chemical Engineering Program, Texas A&M University at Qatar , Education City, PO Box 23874, Doha, Qatar.
authors.forename: Ioannis G
authors.identifier: 0000-0002-2409-6831
authors.initials: IG
authors.lastname: Economou
authors.affiliation: Department of Chemical and Biological Engineering (CBI) and Erlangen Graduate School in Advanced Optical Technologies (SAOT), University of Erlangen-Nuremberg , Paul-Gordan-Straße 6, 91052 Erlangen, Germany.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Rausch
authors.affiliation: Department of Chemical and Biological Engineering (CBI) and Erlangen Graduate School in Advanced Optical Technologies (SAOT), University of Erlangen-Nuremberg , Paul-Gordan-Straße 6, 91052 Erlangen, Germany.
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Fröba