We evaluate the feasibility of electrospinning oil-in-water type emulsions. The emulsions had an aqueous solution of polyethylene oxide (PEO) as the continuous phase, and either mineral oil or a polystyrene (PS) in toluene solution as the drop phase. The Taylor cones and electrified liquid jets were stable even when the emulsion drops were as large as a few-ten microns in diameter. The resulting electrospun PEO fibers incorporated the dispersed phase of the emulsion in the form of drops (in case of mineral oil), or in the form of solid particles (in case of PS). Mineral oil drops appear to be completely encapsulated in the PEO fibers, whereas the PS particles are either incompletely encapsulated, or covered by only a very thin layer of PEO. Calculations show that in both cases, the initially large emulsion drops are broken during the electrospinning process.

When particles adsorb at a fluid/fluid interface at a sufficiently high concentration, the interface loses mobility and displays solidlike characteristics, a phenomenon called "interfacial jamming". Jamming can arrest interfacial tension-driven morphological coarsening in liquid/liquid or gas/liquid systems and therefore stabilize two phase morphologies with unusual interfacial shapes, for example, nonspherical drops and bubbles, and bijels. Here, we conduct a systematic study of interfacial tension-driven jamming of a particle monolayer using a spinning drop tensiometer (SDT). A drop of mineral oil surrounded by ethylene glycol was spun into a cylindrical shape in a SDT. With decreasing rotational rate, the cylindrical drop retracted due to interfacial tension, thus reducing the interfacial area. In the case of particle-covered drops, drop retraction caused an increase in interfacial particle concentration. Accordingly, when the specific interfacial area became comparable to that of a close packing of particles, interfacial jamming occurred and drop retraction was arrested. Fast interfacial contraction or low particle loadings led to less compact jammed monolayers, that is, with a larger specific interfacial area. There was also significant hysteresis between compressing versus expanding the jammed monolayer, suggesting that a certain minimum stress is required for unjamming. Limited experiments with the same particles at a mineral oil/silicone oil interface showed altogether different behavior. In this case, particles did not spread at the interface and a particle-free portion of the interface coexisted with a particle-covered portion. This suggests that the monolayer behavior at this nonpolar/nonpolar interface is dominated by interparticle attraction.

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