Relating the structure and dynamics of ionic liquids under shear by means of reverse non-equilibrium molecular dynamics simulations

Autor(es)

Bernardino, Kalil ^[1] ; Ribeiro, Mauro C. C. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, Lab Espect Mol, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 23, n. 25, p. 13984-13995, JUL 7 2021.
• Citações Web of Science: 0

Resumo

The effect of the shear rate on the viscosity and the structure of 1-ethyl-3-methylimidazolium based ionic liquids with three different anions (tetrafluoroborate, dicyanamide, and bis(trifluoromethylsulfonyl)imide) was studied by means of reverse non-equilibrium molecular dynamics (RNEMD) simulations using a polarizable force field. The three liquids display a Newtonian plateau followed by a shear thinning regime at shear rates of the order of GHz. Even though the main features of the liquid structure remains under shear, systematic changes were noticed at the GHz rates, with coordination shells becoming more diffuse as noticed by the reduction in the difference between consecutive maxima and minima in the radial distribution function. Interestingly, these structural changes with the shear rate can be precisely fitted using the Carreau equation, which is a well-known expression for the shear rate dependence of the viscosity. The fitting parameters for different distributions can be used to explain qualitatively the shear thinning behavior of these liquids. In the GHz range, the cations and, in a minor extension, some anions, tend to assume preferentially a parallel orientation with the flux, which contributes to the shear thinning behavior and may have consequences for adhesion in applications as lubricants. (AU)

• Processo FAPESP: 19/04785-9 - Estudo por dinâmica molecular do efeito da flexibilidade sobre o ponto de fusão de líquidos iônicos
• Beneficiário: Kalil Bernardino
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 17/12063-8 - Dinâmica molecular de não-equilíbrio de líquidos iônicos
• Beneficiário: Kalil Bernardino
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 16/21070-5 - Espectroscopia vibracional com resolução espacial
• Beneficiário: Mauro Carlos Costa Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Temático