Measurement of barrier potentials between colloidal particles and liquid-liquid interfaces

ORAL

Abstract

We measure the repulsive barrier between micron-sized colloidal particles and liquid-liquid interfaces. Particles of polystyrene and silica (suspended in water/glycerol) are confined individually to an optical trap, and translated towards an interface between the aqueous phase and an oil (decane) phase. We fit holographic micrographs of the particles to Lorentz-Mie theory to calculate the positions of the particles within the trap, including axial displacement. Since the force between a particle and the interface is directly related to the particle's displacement from the trap center, we are able to measure the particle-interface repulsion. We compare the force profiles with those predicted by DLVO theory resulting from ``image charges" in the oil phase.

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Authors

  • David Kaz

    Harvard University

  • Ryan McGorty

    Dept. of Physics, Harvard University, Harvard University, Physics Department, Harvard University

  • Vinothan Manoharan

    Dept. of Physics and SEAS, Harvard University, Harvard SEAS, Harvard University, Harvard Physics and SEAS, Harvard University, Physics \& SEAS