Effect of the flexibility and the anion in the structural and transport properties of ethyl-methyl-imidazolium ionic liquids
Data de publicació2007
MetadadesMostra el registre d'unitat complet
This work summarizes some results obtained through equilibrium molecular dynamic simulations regarding the structure and transport properties of several ionic liquids (ILs). The Green–Kubo relationships were employed to evaluate the cation/anion diffusion coefficients, electrical conductivity and shear viscosity at 400 K. The ILs investigated were 1-ethyl-3-methylimidazolium salts of Cl−, NO3 − and PF6 − using two different force fields for the cation: a rigid ion model of 1-ethyl-3-methylimidazolium, studied in a previous work [C. Rey-Castro, L.F. Vega, J. Phys. Chem. B 110 (2006) 14426–14435] and the flexible model of Urahata and Ribeiro [S.M. Urahata, M.C.C. Ribeiro, J. Chem. Phys. 120 (2004) 1855–1863]. Regarding the anions, the most evident difference between the local structures in the three ILs is the position of the first peak of the radial distribution function, reflecting the differences in anion sizes and shapes. The velocity autocorrelation functions are particularly sensitive to the relative weights of anion and cation, although the integrated self-diffusion coefficients do not show significant differences between the Cl−, NO3 − and PF6 − salts. The electric conductivity predicted by the rigid ion model of [emim]Cl is lower than the experimental value, whereas the model overestimates the viscosities. In contrast, the flexible model leads to diffusion rates and conductivities that are one order of magnitude higher at the same temperature. The shear viscosities obtained from simulations of the flexible model are in very good agreement with experimental data. The calculated conductivities are compared with values obtained from the diffusion coefficients through the Nernst–Einstein relation in order to determine the importance of cross-correlation among ions. The stress tensor and the distinct van Hove correlation functions indicate that the dynamics of the local structure of the fluid relaxes faster in the flexible model.
És part deFluid Phase Equilibria, 2007, vol. 256, núm. 1-2, p. 62-69
Projectes de recerca europeus
Mostrant elements relacionats per títol, autor i matèria.
Transport Properties of the Ionic Liquid 1-Ethyl-3-Methylimidazolium Chloride from Equilibrium Molecular Dynamics Simulation. The Effect of Temperature Rey Castro, Carlos; Vega, Lourdes F. (American Chemical Society, 2006)We present here equilibrium molecular dynamics simulation results for self-diffusion coefficients, shear viscosity, and electrical conductivity in a model ionic liquid (1-ethyl-3-methylimidazolium chloride) at ...
Accumulation of Mg to Diffusive Gradients in Thin Films (DGT) devices: Kinetic and thermodynamic effects of the ionic strength Altier Infantes, Alexandra; Jiménez-Piedrahita, Martín; Rey Castro, Carlos; Cecilia Averós, Joan; Galceran i Nogués, Josep; Puy Llorens, Jaume (American Chemical Society, 2016-09-23)Availability of magnesium is a matter of concern due to its role in many environmental and biological processes. Diffusive Gradients in Thin Films (DGT) devices can measure Mg availability in situ. This work shows that Mg ...
Dealing with long‐range interactions in the determination of polyelectrolyte ionization properties. Extension of the transfer matrix formalism to the full range of ionic strengths Garcés, Josep Lluís; Madurga, Sergio; Rey Castro, Carlos; Mas i Pujadas, Francesc (Wiley, 2016-11-14)The ionization state of charged macromolecules in solution is usually determined by the extent of the binding processes. These processes are very sensitive to the ionic strength of the medium, which are of long-range nature. ...