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Passive and Active Microrheology of Hard-sphere Colloids

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Original languageEnglish
Pages (from-to)3806-3812
Number of pages7
JournalJournal of Physical Chemistry B
Volume113
Issue number12
DOIs
Publication statusPublished - 26 Mar 2009

Abstract

We performed passive and active microrheology using probe particles in a bath of well-characterized, model hard-sphere colloids in the fluid state over the whole range of volume fractions below the glass transition. The probe and bath particles have nearly the same size. Passive tracking of probe particles yields short-time self-diffusion coefficients. Comparison with literature data demonstrates that the interaction between probe and bath particles is hard-sphere-like. The short-time diffusivities yield one set of microviscosities as a function of volume fraction, which agrees with previous macrorheological measurements of the high-frequency viscosity of hard-sphere colloids. Using optical tweezers, we measure the force on a trapped probe particle as the rest of the sample is translated at constant velocity. This yields a second set of microviscosities at high Peclet numbers. These agree with previous macrorheological measurements of the high-shear viscosity of similar colloids, at shear-rates below the onset of shear-thickening.

    Research areas

  • STRUCTURAL RELAXATION, NONLINEAR MICRORHEOLOGY, COMPLEX FLUIDS, DISPERSIONS, SUSPENSIONS, MODEL, PARTICLE, MOTION, TRANSITION, VISCOSITY

ID: 1275348