A MD Study of Mixture of a Room-temperature Ionic Liquid and CO2: Solvation Structure and Dynamics, Reorientational Dynamics, Dielectric Relaxation
소속 :
연사 : Research Prof. Youngseon Shim
일시 : 2009-10-28 14:30 ~
장소 : 500동 L306호
일시: 2009년 10월 28일 오후 2:30
장소: 500동 L306호
-Abstract-
Solvation structure and dynamics in a mixture solvent consisting of 1-buthyl-3-methylimidazolium hexafluorophosphate (BMI+PF6-) and carbon dioxide (CO2) are investigated via molecular dynamics computer simulations by employing a model diatomic solute. Comparison with pure solvents BMI+PF6- and CO2 indicates that the extent of preferential solvation in the mixture varies with the solute charge distribution. BMI+PF6- in the mixture shows a strong structure-making around the dipolar solute analogous to the neat ionic liquid. The effective polarity of the mixture, measured as solvation-induced stabilization of a dipolar solute, is substantially maintained from that of the neat BMI+PF6-, consonant with a solvatochromic measurement. Solvent dynamic response of the mixture is dramatically distinguished according to the solute charge distribution, governed by their preferential solvation structure. We also study reorientational dynamics, dielectric and related conductivity behaviors of the mixture and compare with those in the neat BMI+PF6-. CO2 molecules in the mixture make solvent reorientations dramatically accelerated, approaching in the regular diffusion regime. As for both the systems, the anti-correlated ion translational motions are found to enhance the static dielectric constant with generation of a peak in the ion conductivity and strong dielectric absorption, both in the far-IR region. The hindered librational character of ionic current becomes weak in the mixture and thus the static conductivity increases.
In the end, as regards to application of ionic liquids to nanomaterials, our recent study on solvation of single-walled carbon nanotubes in the room-temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborat is introduced. Cations and anions show smeared-out, cylindrical shell-like distributions outside of the nanotubes irrespective of the nanotube diameter and the ion distributions inside the nanotubes vary markedly with their diameter
장소: 500동 L306호
-Abstract-
Solvation structure and dynamics in a mixture solvent consisting of 1-buthyl-3-methylimidazolium hexafluorophosphate (BMI+PF6-) and carbon dioxide (CO2) are investigated via molecular dynamics computer simulations by employing a model diatomic solute. Comparison with pure solvents BMI+PF6- and CO2 indicates that the extent of preferential solvation in the mixture varies with the solute charge distribution. BMI+PF6- in the mixture shows a strong structure-making around the dipolar solute analogous to the neat ionic liquid. The effective polarity of the mixture, measured as solvation-induced stabilization of a dipolar solute, is substantially maintained from that of the neat BMI+PF6-, consonant with a solvatochromic measurement. Solvent dynamic response of the mixture is dramatically distinguished according to the solute charge distribution, governed by their preferential solvation structure. We also study reorientational dynamics, dielectric and related conductivity behaviors of the mixture and compare with those in the neat BMI+PF6-. CO2 molecules in the mixture make solvent reorientations dramatically accelerated, approaching in the regular diffusion regime. As for both the systems, the anti-correlated ion translational motions are found to enhance the static dielectric constant with generation of a peak in the ion conductivity and strong dielectric absorption, both in the far-IR region. The hindered librational character of ionic current becomes weak in the mixture and thus the static conductivity increases.
In the end, as regards to application of ionic liquids to nanomaterials, our recent study on solvation of single-walled carbon nanotubes in the room-temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborat is introduced. Cations and anions show smeared-out, cylindrical shell-like distributions outside of the nanotubes irrespective of the nanotube diameter and the ion distributions inside the nanotubes vary markedly with their diameter
