Molecular Insights into the Regulatable Interfacial Property and Flow Behavior of Confined Ionic Liquids in Graphene Nanochannels

Abstract

The understanding of confined structure and flow property of ionic liquid (IL) in a nanochannel are essential for the efficient application of ILs in the green chemical processes. In this work, the ionic structure and various flow behaviors of ILs inside graphene nanochannels via molecular dynamics simulations are shown. The effect of the nanochannel structure on confined flow is explored, showing that the width mainly heightens the viscosity while the oxidation degree primarily enhances the interfacial friction coefficient. Tuning the width and oxidation degree of nanochannel, three different flow behaviors including Poiseuille, partial plunger and full plunger flow can be achieved, where the second one does not occur in water or other organic solvents. To describe the special flow behavior, an effective influence extent of the nanochannel (w EIE) is defined, whose value can distinguish the above flows effectively. Based on w EIE, the phase diagrams of flow behavior for the nanochannel structure and pressure gradient are obtained, showing that the critical pressure gradient decreases with width and increases with the oxidation degree. Based on the quantitative relations between confined structures, viscosity, friction coefficient, flow behavior, and nanochannel structure, the intrinsic mechanism of regulating the flow behavior and rational design of nanochannel are finally discussed.

Probing the nanofriction of non-halogenated phosphonium-based ionic liquid additives in glycol ether oil on titanium surface

“…Titanium (Ti, foil, thickness 0.25 mm, α-Ti phase) substrates with 99.7% purity and araldite Resin CY212 (CY212) were obtained from Sigma-Aldrich, and Ti was pre-cleaned in ethanol under ultrasonic conditions for 30 minutes. Trihexyltetradecylphosphonium dicyanamide, [P6, 6,6,14][DCA] was purchased from Cytec. Both benzyldimenthylamine (BDMA) and dodecenyl succinic anhydride (DDSA) were from Sinopharm Chemical Reagent Co., Ltd.…”

“…To uncover the fundamental mechanism of Ti surfaces lubricated with IL-oil mixtures at molecular level, molecular dynamics (MD) simulation was performed to investigate the number density distribution of [P6, 6,6,14][BScB]-oil mixtures with a molar ratio of 1:10. As is known, the Ti surface is usually covered by native dense titanium dioxide layers [42], we thus employed the rutile in MD simulations to mimic the substrate that was used in AFM experiments.…”

“…Ionic liquids (ILs) consisting of cations and anions, are liquid-state salts at room temperature, possessing high thermal stability, non-flammability and ionic conductivity, molecular designability, non-volatility, and so on [5][6][7][8]. Typically, ILs offer an ability to resist 'squeeze out' because of their strong interactions with solid surfaces, including van der Waals and electrostatic forces, as well as hydrogen-bonding interactions 2 Friction | https://mc03.manuscriptcentral.com/friction [5,[9][10][11][12][13][14].…”

Theoretical Insights into the Structures and Capacitive Performances of Confined Ionic Liquids

“…Despite the fact that a variety of RTILs are widely used in EDLCs, our understanding of the behavior of RTILs at charged interfaces remains elusive [27]. Most surging focus is on the role of steric and electrostatic forces in the behavior of ionic liquids [28,29], which are much stronger than that in usual electrolytes. However, the effects of the intermolecular dispersion force on the EDL structures and capacitances have been less explored.…”

Water transport performance of inhomgenous nanoconfined systems

“…在纳米受限的环境下, 水的相态也会 发生转变. 前人的大量研究已经发现 [20,[22][23][24][25][26][27][28][29][30][31][32] , 水在受限 环境下存在超过20种结晶态以及3种非晶态或固相态. 在高度受限的体系下, 水的相态变得更为复杂, 被发现 可以形成五边形、六边形和七边形等冰状结构.…”