title: Charged hydrophobic colloids at an oil-aqueous phase interface.
abstract: Hydrophobic poly(methyl methacrylate) (PMMA) colloidal particles, when dispersed in oil with a relatively high dielectric constant, can become highly charged. In the presence of an interface with a conducting aqueous phase, image-charge effects lead to strong binding of colloidal particles to the interface, even though the particles are wetted very little by the aqueous phase. We study both the behavior of individual colloidal particles as they approach the interface and the interactions between particles that are already interfacially bound. We demonstrate that using particles which are minimally wetted by the aqueous phase allows us to isolate and study those interactions which are due solely to charging of the particle surface in oil. Finally, we show that these interactions can be understood by a simple image-charge model in which the particle charge q is the sole fitting parameter.
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Colm P
authors.initials: CP
authors.lastname: Kelleher
authors.affiliation: Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA and Instituto de Fisica, Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico.
authors.forename: Guillermo Iván
authors.initials: GI
authors.lastname: Guerrero-García
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hollingsworth
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Rodrigo E
authors.initials: RE
authors.lastname: Guerra
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Bhaskar Jyoti
authors.initials: BJ
authors.lastname: Krishnatreya
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Grier
authors.affiliation: Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA and Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Vinothan N
authors.initials: VN
authors.lastname: Manoharan
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Chaikin