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Direct nonequilibrium molecular dynamics simulation of diffusio-osmotic flow in nanopores
Hossein Eslami1, Xinxin Deng2, Florian Müller-Plathe2
1Department of Chemistry, College of, Sciences, Persian Gulf University, Boushehr 75168, Iran; Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Peter-Grünberg-Straße 8, 64287 Darmstadt, Germany.
Journal of Colloid and Interface Science
|July 15, 2026
Summary
Diffusio-osmotic flow, driven by solute gradients at interfaces, is controlled by solute-wall interactions. Stronger solute-wall interactions amplify interfacial gradients, reversing flow direction. This clarifies the molecular mechanism of this ubiquitous phenomenon.
Area of Science:
- Fluid Dynamics
- Physical Chemistry
- Nanotechnology
Background:
- Surface-driven flow, or diffusio-osmosis, arises from solute concentration gradients at interfaces.
- This phenomenon is crucial in natural systems and micro/nanofluidics.
- The underlying microscopic mechanisms of diffusio-osmotic flow remain incompletely understood.
Purpose of the Study:
- To elucidate the microscopic mechanisms governing diffusio-osmotic flow.
- To investigate the role of solute-wall and solvent-wall interactions.
- To establish a unified framework for interfacial transport phenomena.
Main Methods:
- Direct nonequilibrium molecular dynamics simulations of a binary fluid mixture in a nanopore.
- Imposing a solute concentration gradient between bulk reservoirs.
- Analyzing interfacial concentration gradients and local pressure tensor.
Main Results:
- Diffusio-osmotic flow direction and magnitude depend on the relative strengths of solute-wall and solvent-wall interactions.
- Stronger solute-wall interactions amplify interfacial concentration gradients, potentially reversing flow.
- A tangential pressure gradient within the interfacial layer, absent in bulk, provides molecular evidence for interfacial driving forces.
Conclusions:
- Diffusio-osmosis is an interfacially driven phenomenon explained by molecular interactions.
- The findings provide a unified framework connecting osmosis, diffusio-osmosis, and diffusio-phoresis.
- Molecular dynamics simulations offer a powerful tool for understanding complex interfacial transport.
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