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Title

The influence of discrete surface charges on the force between charged surfaces

Author(s)

Khan, Malek O.;  Petris, Simon;  Chan, Derek Y. C.

Abstract

The force between two parallel charged flat surfaces, with discrete surface charges, has been calculated with Monte Carlo simulations for different values of the electrostatic coupling. For low electrostatic coupling (small counterion valence, small surface charge, high dielectric constant, and high temperature) the total force is dominated by the entropic contribution and can be described by mean field theory, independent of the character of the surface charges. For moderate electrostatic coupling, counterion correlation effects lead to a smaller repulsion than predicted by mean field theory. This correlation effect is strengthened by discrete surface charges and the repulsive force is further reduced. For large electrostatic coupling the total force for smeared out surface charges is known to be attractive due to counterion correlations. If discrete surface charges are considered the attractive force is weakened and can even be turned into a repulsive force. This is due to the counterions being strongly correlated to the discrete surface charges forming effective, oppositely directed, dipoles on the two walls.

Publication type

Journal article

Source

Journal of Chemical Physics, Vol. 122, no. 10 (Mar 2005), pp. 1-7

Publication year

2005

FOR Code(s)

0306 Physical Chemistry (Incl. Structural);  0904 Chemical Engineering

Keyword(s)

Attractive force;  Charge surfaces;  Colloids;  Computer simulation;  Discretization;  Electrostatics;  Monte Carlo methods;  Permittivity;  Statistical methods;  Surface charge;  Surface properties;  Water

Publisher

American Institute of Physics

ISSN

0021-9606

Publisher URL

http://dx.doi.org/10.1063/1.1856925

Copyright

Copyright © 2005 American Institute of Physics. The published version is reproduced with the kind permission of the publisher.

Full text

Peer reviewed