title: Like-charge interactions between colloidal particles are asymmetric with respect to sign.
abstract: Two-dimensional dispersions of colloidal particles with a range of surface chemistries and electrostatic potentials are characterized under a series of solution ionic strengths. A combination of optical imaging techniques are employed to monitor both the colloid structure and the electrostatic surface potential of individual particlesin situ. We find that like-charge multiparticle interactions can be tuned from exclusively repulsive to long-range attractive by changing the particle surface composition. This behavior is strongly asymmetric with respect to the sign of the surface potential. Collective long-range attractive interactions are only observed among negatively charged particles.
authors.affiliation: Department of Chemical Engineering, University of California, Berkeley, CA, 94720, USA ; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: Esther W
authors.initials: EW
authors.lastname: Gomez
authors.affiliation: Biophysics Graduate Group, University of California, Berkeley, CA, 94720, USA.
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Clack
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: Hung-Jen
authors.initials: HJ
authors.lastname: Wu
authors.affiliation: Biophysics Graduate Group, University of California, Berkeley, CA, 94720, USA ; Howard Hughes Medical Institute ; Department of Chemistry, University of California, Berkeley, CA, 94720, USA ; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: Jay T
authors.initials: JT
authors.lastname: Groves