Multi-Scale Self-Assembly of Anisotropic Colloids using Droplet Evaporation

Evaporation-based self-assembly is a scalable and cost-effective method for precisely ordering nanoparticles into crystalline structures and complex functional materials. The core challenge lies in leveraging the interplay of length-scale-dependent interactions within hybrid hierarchical systems of soft matter and nanomaterials to achieve enhanced physical properties. This presentation will detail the self-organization of nanostructures via solvent evaporation, demonstrating control across multiple length scales. We focus specifically on the crucial role of nanorod shape and size in guiding the assembly and dictating the resulting crystalline phases. We show that evaporation-induced phenomena—including capillary forces, surface tension gradients, and fluid dynamics—bring nanorods together to form ordered structures like superlattices.

We will discuss the formation of intriguing co-existing crystalline phases (e.g., smectic and vertically aligned rods) and present experimental conditions to tune this long-range order into periodic macroscale stripe patterns. Critical parameters influencing assembly, such as nanorod aspect ratio, surface chemistry, and evaporation rate, will be highlighted. Finally, we will present fundamental insights into this colloidal organization using simulation and particle image velocimetry (PIV). By adopting a hybrid hierarchical approach—where precise nanoscale alignment results in macroscopic order—this method offers a scalable platform for fabricating advanced nanomaterials for emerging technologies.