Arrested Development (of Emulsions) – Tim Atherton

Date: Thu. March 27th, 2014, 4:15 pm-5:15 pm
Location: Rockefeller 301

Emulsions – dispersions of “guest” fluid droplets inside another “host” fluid – are very familiar in everyday life as food, consumer products and as raw materials such as crude oil. Despite their ubiquity, they exhibit fascinating and complicated physics. In this talk, I present some recent work on a class of materials, Pickering Emulsions, that also include colloidal particles. With applications ranging from food products to cosmetics via targeted drug delivery systems, the particles provide an efficient way to control an emulsion’s structure, properties and functions. For example, particles adsorbed on the interface of the droplets can be used to control the rate at which they coalesce, which in turn affects the overall rate at which the emulsion separates. When fluid emulsion droplets are brought in contact, a reduction of the interfacial tension drives their coalescence into a larger droplet of the same total volume and reduced exposed area. This coalescence can be partially or totally hindered by the presence of nano or micron-size particles that coat the interface as they become crowded, arresting further evolution of the droplet. A similar process can stabilize deformed droplets as they relax back to their equilibrium shape. I’ll discuss some of our recent theoretical work on understanding the ordering that emerges in these systems, as well as results from our experimental collaborators on actualizing them.