Bicontinuous emulsions stabilized solely by colloidal particles
Recent large-scale computer simulations suggest that it may be possible to create a new class of soft solids, called ?bijels?, by stabilizing and arresting the bicontinuous interface in a binary liquid demixing via spinodal decomposition using particles that are neutrally wetted by both liquids. The interfacial layer of particles is expected to be semi-permeable; hence, if realized, these new materials would have many potential applications, for example, as micro-reaction media. However, the creation of bijels in the laboratory faces serious obstacles. In general, fast quench rates are necessary to bypass nucleation, so that only samples with limited thickness can be produced, which destroys the three-dimensionality of the putative bicontinuous network. Moreover, even a small degree of unequal wettability of the particles by the two liquids can lead to ill-characterized, ?lumpy? interfacial layers and therefore irreproducible material properties. Here, we report a reproducible protocol for creating three-dimensional samples of bijel in which the interfaces are stabilized by essentially a single layer of particles. We demonstrate how to tune the mean interfacial separation in these bijels, and show that mechanically, they indeed behave as soft solids. These characteristics and their tunability will be of great value for microfluidic applications.
The historic takeover of Fannie Mae and Freddie Mac, which could come as soon as this weekend, moved to the forefront of the presidential campaign Saturday.
In the arena that night, the whole last minute was drowned out by cheers — and then when the soaring music swelled, the confetti rained down as the harbinger of balloons and the hopeful first family took the stage, forget about it — it was a perfect end to a convention that last Monday, no one even knew if it would happen. But it did, and I'm so glad to have been there.
