Self-assembly of Colloidal Hematite in Evaporating Droplets

The self-assembly of materials by utilizing the inherent directionality of the constituent particles is of both practical and fundamental interest.  By employing evaporation assisted self-assembly, we assemble micro-sized magnetic and non-magnetic superball particles into ordered structures. We study the assembly process by drying dispersion droplets in the presence and absence of an external magnetic field with in-situ small angle x-ray scattering (SAXS), and we compare the assemblies of magnetic and non-magnetic superballs with the same shape. The resulting assemblies geometry is investigated by altering the magnetic field strength, magnetic interparticle interactions, and particle shape. Tuning these interactions provides insights for the controllable formation of colloidal clusters as functional materials.