## Abstract

A closed-form analytical model has been developed to estimate the effect of a nonuniform surface charge distribution on the potential of mean force between two plates or two spherical colloidal particles. This model is an extension for randomly charged surfaces of the well-known Hogg-Healy-Fuerstenau model. The surface charge distribution is random, and we characterize this by defining (1) N equal-area regions on the surfaces, (2) an average surface potential (〈ζ〉), and (3) a standard deviation of surface potential (σ_{ζ}) among the regions. The model predicts that the standard deviation of the potential of mean force (σ_{Φ}) at any gap distance is approximately proportional to σ_{ζ}/√N. The practicality of the model derives from the fact that σ_{ζ}/√N is experimentally measurable. Charge nonuniformity provides one explanation for why classical colloidal stability theory often fails. In addition, since regions with a low charge density tend to be more hydrophobic, charge nonuniformity might allow strong hydrophobic interactions between particles.

Original language | English (US) |
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Pages (from-to) | 7687-7693 |

Number of pages | 7 |

Journal | Langmuir |

Volume | 17 |

Issue number | 24 |

DOIs | |

State | Published - Nov 27 2001 |

## All Science Journal Classification (ASJC) codes

- General Materials Science
- Condensed Matter Physics
- Surfaces and Interfaces
- Spectroscopy
- Electrochemistry