Sculpting high aspect ratio particles from oil-in-water emulsions

Shape is a powerful route to control the transport and rheological properties of particulate media. Here, we present a process to sculpt elongated colloidal particles from an oil-in-water emulsion. Oil droplets are crystallized by reducing the temperature. The rate of cooling determines the rate of crystallization. With the addition of surfactants, it is possible to induce dewetting of the crystals by their own liquid phase. By tuning the relative rates of dewetting and crystallization, a rich variety of crystal shapes can be grown in an easily scalable process using controlled interfacial hydrodynamics. We explain these experimental findings using a non-equilibrium Monte Carlo model that captures both the crystallization and dewetting processes. Our results reproduce the wide range of shapes seen in experiment and provide insights to control their final morphology. Prospects for expanding the space of final shapes will also be discussed.