Experimental Soft Matter Physics
A simple cartoon illustration of depletion attraction. The disperse phase particles are the large grey spheres, stabilized by e.g. a surfactant that induces an excluded volume (green corona) for the depletants (orange particles). When both particle species are present at sufficient concentration the osmotic pressure from depletants excluded from the volume between the large particles lead to aggregation of the latter.
Structures generated by instabilities
Turn on the water faucet in your kitchen or your bathroom and study the stream of water as it leaves the faucet: you will see how the stream is soon broken up into droplets. This is a result of the so-called Plateau-Rayleigh instability, driven by energy minimization under the action of surface tension. Several other instabilities can be induced in liquids, variations being introduced by incorporating substrates of different shapes and/or chemistry, as well as by dissolving specific solutes in the liquids. We study such instabilities, sometimes fighting against them, for instance in order to spin continuous fibers using electrospinning, sometimes triggering them deliberately and in a controlled manner, in order to produce discrete entities such as liquid crystalline shells. By playing around with the components involved we can tune the details of the process, and thereby influence the final product. And in the process we see some fascinating physics.
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