| Full text | |
| Author(s): |
Total Authors: 2
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| Affiliation: | [1] Univ Sao Paulo, Lab Espectroscopia Mol, Dept Quim Fundamental, Inst Quim, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil
Total Affiliations: 1
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| Document type: | Journal article |
| Source: | Journal of Chemical Physics; v. 148, n. 19 MAY 21 2018. |
| Web of Science Citations: | 5 |
| Abstract | |
Molecular dynamics (MD) simulations of five ionic liquids based on 1-alkyl-3-methylimidazolium cations, {[}C(n)C(1)im](+), have been performed in order to calculate high-frequency elastic moduli and to evaluate heterogeneity of local elastic moduli. The MD simulations of {[}C(n)C(1)im]{[}NO3], n = 2, 4, 6, and 8, assessed the effect of domain segregation when the alkyl chain length increases, and {[}C(8)C(1)im]{[}PF6] assessed the effect of strength of anion-cation interaction. Dispersion curves of excitation energies of longitudinal and transverse acoustic, LA and TA, modes were obtained from time correlation functions of mass currents at different wavevectors. High-frequency sound velocity of LA modes depends on the alkyl chain length, but sound velocity for TA modes does not. High-frequency bulk and shear moduli, K infinity and G infinity, depend on the alkyl chain length because of a density effect. Both K infinity and G infinity are strongly dependent on the anion. The calculation of local bulk and shear moduli was accomplished by performing bulk and shear deformations of the systems cooled to 0 K. The simulations showed a clear connection between structural and elastic modulus heterogeneities. The development of nano-heterogeneous structure with increasing length of the alkyl chain in {[}C(n)C(1)im]{[}NO3] implies lower values for local bulk and shear moduli in the non-polar domains. The mean value and the standard deviations of distributions of local elastic moduli decrease when {[}NO3](-) is replaced by the less coordinating {[}PF6](-) anion. Published by AIP Publishing. (AU) | |
| FAPESP's process: | 12/13119-3 - Vibrational spectroscopy in condensed phases |
| Grantee: | Mauro Carlos Costa Ribeiro |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 14/13134-8 - A study by computational simulation of ionic liquids stress heterogeneity |
| Grantee: | Arnold Adriaan Veldhorst |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |