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**Grandner, S. ; Zeng, Y. ; Klitzing, R. von ; Klapp, S. H. L.** (2009):

*Impact of surface charges on the solvation forces in confined colloidal solutions.*

In: Journal of Chemical Physics, 131 (15), AIP Publishing, ISSN 0021-9606,

DOI: 10.1063/1.3246844,

[Article]

## Abstract

Combining computer simulations and experiments we address the impact of charged surfaces on the solvation forces of a confined, charged colloidal suspension (slit-pore geometry). Investigations based on the colloidal-probe atomic-force-microscope technique indicate that an increase in surface charges markedly enhances the oscillations of the force in terms of their amplitude. To understand this effect on a theoretical level we perform grand-canonical Monte-Carlo simulations (GCMC) of a coarse-grained model system. It turns out that various established approaches of the interaction between a charged colloid and a charged wall, such as linearized Poisson–Boltzmann (PB) theory involving the bulk screening length, do not reproduce the experimental observations. We thus introduce a modified PB potential with a space-dependent screening parameter. The latter takes into account, in an approximate way, the fact that the charged walls release additional (wall) counterions which accumulate in a thin layer at the surface(s). The resulting, still purely repulsive fluid-wall potential displays a nonmonotonic behavior as function of the surface potential with respect to the strength and range of repulsion. GCMC simulations based on this potential reproduce the experimentally observed charge-induced enhancement in the force oscillations. We also show, both by experiment and by simulations, that the asymptotic wave- and decay length of the oscillating force do not change with the wall charge, in agreement with predictions from density functional theory.

Item Type: | Article |
---|---|

Erschienen: | 2009 |

Creators: | Grandner, S. ; Zeng, Y. ; Klitzing, R. von ; Klapp, S. H. L. |

Title: | Impact of surface charges on the solvation forces in confined colloidal solutions |

Language: | English |

Abstract: | Combining computer simulations and experiments we address the impact of charged surfaces on the solvation forces of a confined, charged colloidal suspension (slit-pore geometry). Investigations based on the colloidal-probe atomic-force-microscope technique indicate that an increase in surface charges markedly enhances the oscillations of the force in terms of their amplitude. To understand this effect on a theoretical level we perform grand-canonical Monte-Carlo simulations (GCMC) of a coarse-grained model system. It turns out that various established approaches of the interaction between a charged colloid and a charged wall, such as linearized Poisson–Boltzmann (PB) theory involving the bulk screening length, do not reproduce the experimental observations. We thus introduce a modified PB potential with a space-dependent screening parameter. The latter takes into account, in an approximate way, the fact that the charged walls release additional (wall) counterions which accumulate in a thin layer at the surface(s). The resulting, still purely repulsive fluid-wall potential displays a nonmonotonic behavior as function of the surface potential with respect to the strength and range of repulsion. GCMC simulations based on this potential reproduce the experimentally observed charge-induced enhancement in the force oscillations. We also show, both by experiment and by simulations, that the asymptotic wave- and decay length of the oscillating force do not change with the wall charge, in agreement with predictions from density functional theory. |

Journal or Publication Title: | Journal of Chemical Physics |

Volume of the journal: | 131 |

Issue Number: | 15 |

Publisher: | AIP Publishing |

Divisions: | 05 Department of Physics 05 Department of Physics > Institute for condensed matter physics (2021 merged in Institute for Condensed Matter Physics) |

Date Deposited: | 28 Apr 2017 11:05 |

DOI: | 10.1063/1.3246844 |

Additional Information: | Art.No.: 154702; Erstveröffentlichung |

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