A multi-scale perspective of gas transport through soap-film membranes

Abstract

Soap films represent unique aqueous systems, whose physical properties can be tuned by acting on their nanoscale structure. Here, we specifically focus on transport properties through membranes realized in the form of soap films. While diffusion phenomena in the water core and surfactant monolayers are described using a continuum model, molecular dynamics is used to compute the static and dynamical properties of water, gases and the surfactant in the monolayers which is hexaethylene glycol monododecyl ether (C₁₂E₆). The obtained atomistic details are then incorporated into a drift-diffusion model for consistently extracting a boundary condition for the above continuum model describing transport phenomena at a larger scale. Numerical predictions are validated against experimental data from both properly designed experiments and the literature. Finally, the developed model is used to estimate the characteristic time for disparate gas mixing when initially separated by soap film membranes.