No abstract

Anisotropic endoskeletal droplets are produced continuously in a microfluidic device. The device temperature is controlled such that droplets are formed in a fluid state and subsequently cooled to crystallize an internal network that retains an anisotropic shape. Droplets that are forced to collide after crystallizing partially coalesce to form linear droplet superstructures with tunable rigidity. Superstructure filaments can be folded into larger, three-dimensional percolating fluid networks with tunable porosity and size, which can be further controlled by temperature. The results of this work provide a means of generating hierarchical porous structures with continuous liquid interfaces on demand in a process similar to three-dimensional printing.

A model of internally structured emulsion droplets is presented that accounts for the traction forces generated by interfacial tension and the von Mises yield criterion of the internal supporting network. For symmetric droplets, the method calculates the total stress acting on a droplet locally, allowing droplet stability and location of failure to be predicted. It is not regions of high interfacial curvature that prompt droplet reconfiguration, rather regions transitioning from high to low curvature. The model enables the design of emulsion droplet response and reconfigurability to external triggers such as changes in surface tension (surfactant concentration) and temperature.