title: Altering surface charge nonuniformity on individual colloidal particles.
abstract: Charge nonuniformity (sigmazeta) was altered on individual polystyrene latex particles and measured using the novel experimental technique of rotational electrophoresis. It has recently been shown that unaltered sulfated latices often have significant charge nonuniformity (sigmazeta = 100 mV) on individual particles. Here it is shown that anionic polyelectrolytes and surfactants reduce the native charge nonuniformity on negatively charged particles by 80% (sigmazeta = 20 mV), even while leaving the average surface charge density almost unchanged. Reduction of charge uniformity occurs as large domains of nonuniformity are minimized, giving a more random distribution of charge on individual particle surfaces. Targeted reduction of charge nonuniformity opens new opportunities for the dispersion of nanoparticles and the oriented assembly of particles.
authors.affiliation: The Pennsylvania State University, Department of Chemical Engineering, University Park, Pennsylvania 16802, USA.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Feick
authors.forename: Nkiru
authors.initials: N
authors.lastname: Chukwumah
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Noel
authors.forename: Darrell
authors.initials: D
authors.lastname: Velegol