Molecular Topology and Local Dynamics Govern the Viscosity of Imidazolium-Based Ionic Liquids

• DOI: 10.1021/acs.jpcb.5b08245
• Publication Date: 2015-10-27T20:47:40Z
• Authors: Yong Zhang; Lianjie Xue; Fardin Khabaz; Rose Doerfler; Edward L. Quitevis; Rajesh Khare; Edward J. Maginn
• Keywords: 01 natural sciences; 0104 chemical sciences

A series of branched ionic liquids (ILs) based on the 1-(iso-alkyl)-3-methylimidazolium cation from 1-(1-methylethyl)-3-methylimidazolium bistriflimide to 1-(5-methylhexyl)-3-methylimidazolium and linear ILs 1-(n-alkyl)-3-methylimidazolium 1-propyl-3-methylimidazolium 1-heptyl-3-methylimidazolum were recently synthesized their physicochemical properties characterized. For with same number carbons in alkyl chain, IL was found have density but higher viscosity than one. In addition, 1-(2-methylpropyl)-3-methylimidazolium ([2mC3C1Im][NTf2]) an abnormally high viscosity. Motivated by these experimental observations, studied using molecular dynamics (MD) simulations current work. The viscosities each calculated equilibrium MD method at 400 K nonequilibrium 298 K. results agree trend. ion pair (IP) lifetime, spatial distribution function, associated potential mean force, size shape, interaction energy components simulations. quantitative correlation between liquid structure observed. Analysis shows that are due relatively more stable packing cations anions indicated lower minima force (PMF) surface. abnormal [2mC3C1Im][NTf2] be result specific side chain length structure.