Interactions between amphoteric surfaces with strongly overlapping double layers

The entropic repulsion between strongly overlapping electrical double-layers from two parallel amphoteric plates is described via the Donnan equilibrium in the limit of zero electric field. The plates feature charge-regulation and the inter-plate solution is in equilibrium with a reservoir of a mono...

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Bibliographic Details
Published in:Soft matter 2018, Vol.14 (23), p.472-471
Main Authors: Vis, Mark, Tuinier, Remco, Kuipers, Bonny W. M, Vrij, Agienus, Philipse, Albert P
Format: Article
Language:English
Subjects:
Amphoterics
Contact potentials
Contact pressure
Decay
Electric contacts
Electric potential
Plates
Poisson equation
Pressure
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Summary:The entropic repulsion between strongly overlapping electrical double-layers from two parallel amphoteric plates is described via the Donnan equilibrium in the limit of zero electric field. The plates feature charge-regulation and the inter-plate solution is in equilibrium with a reservoir of a monovalent electrolyte solution. A finite electric potential and disjoining pressure is found at contact between the plates, due to a complete discharging of the plates. For low potentials, the decay of potential and pressure is fully governed by a characteristic length scale and the contact potential. Additionally, for large separations we find a universal inverse square decay of disjoining pressure, irrespective of the contact potential. The results of the Donnan theory show quantitative agreement with self-consistent field computations that solve the full Poisson equation. The entropic repulsion between strongly overlapping electrical double-layers from two parallel amphoteric plates is described via the Donnan equilibrium in the limit of zero electric field.
ISSN:1744-683X
1744-6848
DOI:10.1039/c8sm00662h