Chemical Society Seminar: David T. Wu - From simplicity emerges complexity: Field-directed assembly of structured 2d colloidal phases

Abstract:

Colloids have been a rich system for exploring and understanding the emergent structures and behaviors of large collections of simple particles. This is due to the experimentally accessible time and length scales for observing colloids as well as our ability to control interparticle interactions. Furthermore, applied electric and magnetic fields allow for directed assembly as well as propulsion of colloids. When confined at a surface, colloids develop competing interactions that lead to rich and unexpected collective structure and dynamics, that moreover can be predicted by theory and Monte Carlo Simulation (Maestas et al., ACS Nano 2021, 15, 2399).

I present our studies combining experiments and modeling of several types of self-assembled structures, including 1) the spontaneous formation of “colloidal molecules” and their reactions, 2) formation of regular and frustrated arrays of spheres and of dimers, 3) spontaneous assembly and propulsion of chiral clusters and 4) the formation and deformations of a new class of bilayer quasicrystals.

These mechanisms of directed assembly, i.e. normal applied fields and asymmetric surface confinement, are general and do not depend strongly on the chemical nature of the colloids. It is hoped such approaches can be employed in a wide range of material systems.

Bio: