Figure. Sudden dispersion of sand particles sprinkled onto water in a Petri dish. Notice the streak lines formed due to the radially-outward motion of the particles emanating from the location where they were sprinkled.
(Collaborative project with Dr. Susan Pell and Dr. Ian Fischer)
The focus of this work is to understand the physics behind spontaneous dispersion of particles when they come in contact with a fluid-fluid interface (see the figure below). We have recently shown:
- that this can cause particles sprinkled over a small area to spread almost instantaneously over an area that is several orders of magnitudes larger;
- a dropped particle causes particles already trapped on the interface to move away, creating a particle-free region around a newly-adsorbed particle; and
- influence the nature of monolayer clusters, e.g., porosity, on interfaces that are formed.
These phenomena have importance in a wide range of applications, such as pollination in hydrophilous plants, flotation and spreading of viruses and nanoparticles, self-assembly of micron- to nano-sized particles, stabilization of emulsions, etc. While the focus of the past studies has been on understanding the mechanisms by which particles already trapped on fluid-fluid interfaces interact leading to their self-assembly into monolayered patterns, the sudden dispersion of particles coming into contact with a fluid-fluid interface which is being investigated has not been previously considered.
Dispersion