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Screened Coulomb interactions with non-uniform surface charge

Accepted version
Peer-reviewed

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Type

Article

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Authors

Ghosal, S 
Sherwood, JD 

Abstract

The screened Coulomb interaction between a pair of infinite parallel planes with spatially varying surface charge is considered in the limit of small electrical potentials for arbitrary Debye lengths. A simple expression for the disjoining pressure is derived in terms of a two-dimensional integral in Fourier space. The integral is evaluated for periodic and random charge distributions and the disjoining pressure is expressed as a sum over Fourier–Bloch reciprocal lattice vectors or in terms of an integral involving the autocorrelation function, respectively. The force between planes with a finite area of uniform charge, a model for the DLVO interaction between finite surfaces, is also calculated. It is shown that the overspill of the charge cloud beyond the region immediately between the charged areas results in a reduction of the disjoining pressure, as reported by us recently in the long Debye length limit for planes of finite width.

Description

Keywords

colloids, soft matter, electrokinetics, DLVO interaction, disjoining pressure, screened Coulomb interactions

Journal Title

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science

Conference Name

Journal ISSN

1364-5021
1471-2946

Volume Title

473

Publisher

Royal Society Publishing