Tuning Colloidal Self-Assembly through Engineered Surface Roughness

We use two-photon polymerization to 3D-print polygonal colloidal particles—rectangles and hexagons—with controlled combinations of smooth and rough faces. By adjusting a key design parameter during printing, we precisely tune the surface roughness of each particle. This control over roughness directly modifies the interparticle interactions, providing a new handle to direct self-assembly.

Experimentally, we observe that roughness strongly influences the resulting structures: rectangular particles form linear, fiber-like aggregates, while hexagonal ones assemble into trimer-like clusters. Our results demonstrate how tuning particle roughness through fabrication parameters can be used to steer colloidal interactions and design targeted self-assembled morphologies. In parallel, we model the system using molecular dynamics simulations to study the dynamics of assembly.