title: Measurement of long-range repulsive forces between charged particles at an oil-water interface.
abstract: Using a laser tweezers method, we have determined the long-range repulsive force as a function of separation between two charged, spherical polystyrene particles (2.7 microm diameter) present at a nonpolar oil-water interface. At large separations (6 to 12 microm between particle centers) the force is found to decay with distance to the power -4 and is insensitive to the ionic strength of the aqueous phase. The results are consistent with a model in which the repulsion arises primarily from the presence of a very small residual electric charge at the particle-oil interface. This charge corresponds to a fractional dissociation of the total ionizable (sulfate) groups present at the particle-oil surface of approximately 3 x 10(-4).
authors.affiliation: Surfactant & Colloid Group, Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Aveyard
authors.forename: B P
authors.initials: BP
authors.lastname: Binks
authors.forename: J H
authors.initials: JH
authors.lastname: Clint
authors.forename: P D I
authors.initials: PD
authors.lastname: Fletcher
authors.forename: T S
authors.initials: TS
authors.lastname: Horozov
authors.forename: B
authors.initials: B
authors.lastname: Neumann
authors.forename: V N
authors.initials: VN
authors.lastname: Paunov
authors.forename: J
authors.initials: J
authors.lastname: Annesley
authors.forename: S W
authors.initials: SW
authors.lastname: Botchway
authors.forename: D
authors.initials: D
authors.lastname: Nees
authors.forename: A W
authors.initials: AW
authors.lastname: Parker
authors.forename: A D
authors.initials: AD
authors.lastname: Ward
authors.forename: A N
authors.initials: AN
authors.lastname: Burgess