Investigations of the coalescence of emulsion droplets with microfluidics
- Event time: 2:00pm
- Event date: 28th September 2009
- Speaker: Nicolas Bremond (Laboratoire Colloides et Materiaux Divises ESPCI Paris)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
The coalescence of neighboring droplets is the main destabilization process of an emulsion that may be suppressed or triggered depending on the application. The development of microfluidic technology has offered us the opportunity to design an experimental tool for probing such phenomenon at the scale of a droplet. I will present two investigations that rely on this experimental approach. The first one concerns the destabilization of an emulsion induced by a hydrodynamic forcing where we demonstrate a counterintuitive phenomenon: coalescence occurs during the separation phase and not during the impact of two droplets. We note that the fusion mechanism is responsible for a cascade of coalescence events in a concentrated emulsion. This mechanism may play a major role in the phase inversion or the rapid collapse of an emulsion. The second investigation is about the breaking of an emulsion by an electric field. Three different regimes are found: stable, coalescence, and partial merging. From these findings, we can propose a destruction mechanism for a macroscopic emulsion, which includes the packing condition for which total and immediate destruction is effective.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..