Issue 10, 2018

Liquid–liquid displacement in slippery liquid-infused membranes (SLIMs)

Abstract

Liquid-infused membranes inspired by slippery liquid-infused porous surfaces (SLIPS) have been recently introduced to membrane technology. The gating mechanism of these membranes is expected to give rise to anti-fouling properties and multi-phase transport capabilities. However, the long-term retention of the infusion liquid has not yet been explored. To address this issue, we investigate the retention of the infusion liquid in slippery liquid-infused membranes (SLIMs) via liquid–liquid displacement porometry (LLDP) experiments combined with microscopic observations of the displacement mechanism. Our results reveal that pores will be opened corresponding to the capillary pressure, leading to preferential flow pathways for water transport. The LLDP results further suggest the presence of liquid-lined pores in SLIM. This hypothesis is analyzed theoretically using an interfacial pore flow model. We find that the displacement patterns correspond to capillary fingering in immiscible displacement in porous media. The related physics regarding two-phase flow in porous media is used to confirm the permeation mechanism appearing in SLIMs. In order to experimentally observe liquid–liquid displacement, a microfluidic chip mimicking a porous medium is designed and a highly ramified structure with trapped infusion liquid is observed. The remaining infusion liquid is retained as pools, bridges and thin films around pillar structures in the chip, which further confirms liquid-lining. Fractal dimension analysis, along with evaluation of the fluid (non-wetting phase) saturation, further confirms that the fractal patterns correspond to capillary fingering, which is consistent with an invasion percolation with trapping (IPT) model.

Graphical abstract: Liquid–liquid displacement in slippery liquid-infused membranes (SLIMs)

Supplementary files

Article information

Article type
Paper
Submitted
27 Nov 2017
Accepted
02 Feb 2018
First published
09 Feb 2018
This article is Open Access
Creative Commons BY-NC license

Soft Matter, 2018,14, 1780-1788

Liquid–liquid displacement in slippery liquid-infused membranes (SLIMs)

H. Bazyar, P. Lv, J. A. Wood, S. Porada, D. Lohse and R. G. H. Lammertink, Soft Matter, 2018, 14, 1780 DOI: 10.1039/C7SM02337E

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