Arrested coalescence of particle-coated droplets into nonspherical supracolloidal structures.

Colloidal and supracolloidal structures with anisotropic shape and surface chemistry are potential building blocks for the fabrication of novel materials. Droplets or bubbles are often used as templates for the assembly of particles into supracolloidal structures of spherical shape. Particle-coated droplets or bubbles have recently been shown to also retain nonspherical geometries after deformation, suggesting that the templating approach can also be used to produce supracolloidal structures with anisotropic shape. We show that partially coated droplets generated in a microcapillary device can undergo spontaneous coalescence into stable nonspherical structures. By positioning the droplets into regular arrays before coalescence, we produce anisotropic geometries with well-defined bonding angles between adjacent merged droplets. This approach allows for the fabrication of novel anisotropic supracolloidal structures with deliberately designed shapes.