Osmotic and diffusio-osmotic flow generation at high solute concentration. II. Molecular dynamics simulations

Abstract

In this paper, we explore osmotic transport by means of molecular dynamics (MD) simulations. We first consider osmosis through a membrane, and investigate the reflection coefficient of an imperfectly semi-permeable membrane, in the dilute and high concentration regimes. We then explore the diffusio-osmotic flow of a solute-solvent fluid adjacent to a solid surface, driven by a chemical potential gradient parallel to the surface. We propose a novel non-equilibrium MD (NEMD) methodology to simulate diffusio-osmosis, by imposing an external force on every particle, which properly mimics the chemical potential gradient on the solute in spite of the periodic boundary conditions. This NEMD method is validated theoretically on the basis of linear-response theory by matching the mobility with their Green-Kubo expressions. Finally, we apply the framework to more realistic systems, namely a water-ethanol mixture in contact with a silica or a graphene surface.

Effect of the interaction strength and anisotropy on the diffusio-phoresis of spherical colloids

“…This approach is less suited for systems with pe-riodic boundary conditions. However, as shown in recent papers, the gradient can also be imposed as an external force acting on the chemical identity (in the case of diffusio-phoresis) or the excess enthalpy (in the case of thermophoresis) of individual particles 44,45 .…”

What Controls Thermo-osmosis? Molecular Simulations Show the Critical Role of Interfacial Hydrodynamics

“…Thermophoretic phenomena, referring to the influence of temperature gradients on the flux of colloidal particles, were firstly studied for numerous applications such as optothermal DNA trapping or diseaserelated protein aggregates identification [1][2][3][4][5][6][7][8], and this interest for thermophoresis fostered work on its theoretical description [9][10][11][12][13]. On the other hand, at variance with what has been done for electro-osmosis [14][15][16][17][18][19][20][21][22] and diffusio-osmosis [23][24][25][26], very limited theoretical work has been done so far on thermo-osmosis at solid-liquid interfaces.…”

Stability and Structure of Adaptive Self-organized Supramolecular Artificial Water Channels in Lipid Bilayers

“…Moreover, the current studies were only tackling the stability and permeation mechanisms at equilibrium. Yet structural changes of such systems composed by a large number of interacting molecules has to be challenged under nonequilibrium conditions such as osmotic gradients or hydrostatic pressure [25,26]. Such considerations as a comparison between diffusional and osmotic single-channel permeabilities need to be clarified on these systems, in order to enlighten experimental observations in real systems.…”