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Issue 18, 2017
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Electro-osmosis at surfactant-laden liquid–gas interfaces: beyond standard models

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Abstract

Electro-osmosis (EO) is a powerful tool to manipulate liquids in micro and nanofluidic systems. While EO has been studied extensively at liquid–solid interfaces, the case of liquid–vapor interfaces, found e.g. in foam films and bubbles, remains to be explored. Here we perform molecular dynamics (MD) simulations of EO in a film of aqueous electrolyte covered with fluid layers of ionic surfactants and surrounded by gas. Following the experimental procedure, we compute the zeta potential from the EO velocity, defined as the velocity difference between the middle of the liquid film and the surrounding gas. We show that the zeta potential can be smaller or larger than existing predictions depending on the surfactant coverage. We explain the failure of previous descriptions by the fact that surfactants and bound ions move as rigid bodies and do not transmit the electric driving force to the liquid locally. Considering the reciprocal streaming current effect, we then develop an extended model, which can be used to predict the experimental zeta potential of surfactant-laden liquid–gas interfaces.

Graphical abstract: Electro-osmosis at surfactant-laden liquid–gas interfaces: beyond standard models

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Publication details

The article was received on 20 Feb 2017, accepted on 10 Apr 2017 and first published on 11 Apr 2017


Article type: Paper
DOI: 10.1039/C7SM00358G
Citation: Soft Matter, 2017,13, 3341-3351
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    Electro-osmosis at surfactant-laden liquid–gas interfaces: beyond standard models

    A. Barbosa De Lima and L. Joly, Soft Matter, 2017, 13, 3341
    DOI: 10.1039/C7SM00358G

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