title: Electrostatic interaction between nonuniformly charged colloids: experimental and numerical study.
abstract: The influence of the surface charge distribution on the interaction between nanosized particles in water is reported. The distribution of charges at the surface of initially neutral microemulsion droplets has been modulated by additions of various oligomeric cationic surfactants. The osmotic compressibility of the doped microemulsions was measured by light and small-angle neutrons scattering and reveals that the overall effective interaction induced by the ionic groups is repulsive. However, particular charge distributions decrease the osmotic compressibility much less than others. Independent measurements of the activity of the bromide counterions with specific electrodes evidence a significant decrease in the effective charge, which, however, cannot account for the osmotic compressibility in the framework of the primitive model. The q dependence of the structure factor reveals an attractive contribution over a short distance. Numerical studies assign this attractive contribution to the overlap of hydration shells that are extended as a result of the charge localization.
authors.affiliation: Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier , Montpellier, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Derot
authors.forename: Lionel
authors.initials: L
authors.lastname: Porcar
authors.forename: YongJin
authors.initials: Y
authors.lastname: Lee
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Pincus
authors.forename: YongSeok
authors.initials: Y
authors.lastname: Jho
authors.forename: Martin
authors.initials: M
authors.lastname: In
mesh_terms: D000473:Alkanes / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D009995:Osmosis; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000473:Alkanes; D003102:Colloids; D004987:Ethers; D013501:Surface-Active Agents; D014867:Water; C012867:decane