Off-equilibrium surface tension in colloidal suspensions.

Reverse Micelles Enable Strong Electrostatic Interactions of Colloidal Particles in Nonpolar Solvents

While the important role of electrostatic interactions in aqueous colloidal suspensions is widely known and reasonably well-understood, the relevance of charge in nonpolar suspensions remains mysterious. We demonstrate that particles can have surprisingly strong electrostatic interactions in low dielectric constant environments when ions are solubilized by reverse micelles. A simple thermodynam...

Real-space imaging of nucleation and growth in colloidal crystallization.

Crystallization of concentrated colloidal suspensions was studied in real space with laser scanning confocal microscopy. Direct imaging in three dimensions allowed identification and observation of both nucleation and growth of crystalline regions, providing an experimental measure of properties of the nucleating crystallites. By following their evolution, we identified critical nuclei, determi...

A Lattice-Boltzmann model for suspensions of self-propelling colloidal particles.

We present a Lattice-Boltzmann method for simulating self-propelling (active) colloidal particles in two dimensions. Active particles with symmetric and asymmetric force distribution on their surface are considered. The velocity field generated by a single active particle, changing its orientation randomly, and the different time scales involved are characterized in detail. The steady-state spe...

Structure and Dynamics of Equilibrium and Non-Equilibrium Systems: Colloidal Suspensions in Confining Light Fields

Charging and discharging of single colloidal particles at oil/water interfaces

The physical behavior of solid colloids trapped at a fluid-fluid interface remains in itself an open fundamental issue. Here, we show that the gradients of surface tension can induce particles to jet towards the oil/water interface with velocities as high as ≈ 60 mm/s when particle suspensions come in contact with the interface. We hypothesize that rubbing between the particles and oil lead to ...