Controlled orientation of droplets in ellipsoid-filled polymeric emulsions by particle parameters and flow conditions

The effect of particle parameters (aspect ratio, AR, and concentration) and flow conditions (gap spacing and shear rate) on droplet orientation deformation behavior in polystyrene (PS) particle-filled binary polymeric emulsions is investigated by using rheo-optical technique and confocal microscopy. Interesting vorticity orientation behavior is achieved by tailoring experimental conditions to gain rigid anisotropic droplets during slow confined shear flow. PS ellipsoids with high AR are found to reside both at the fluid interface in a monolayer side-on state and inside droplets, leading to the formation of rigid anisotropic droplets due to interfacial/bulk jamming effect at appropriate particle concentrations. In unconfined bulk samples, droplets with vorticity orientation can also be observed under the wall migration effect and confinement effect arising from nearby droplets. However, too strong wall confinement effect remarkably facilitates the coalescence of vorticity-aligned droplets during slow shear...