Dynamic adaptive colloidal crystals far from equilibrium

Abstract

Self-assembly has been the center of attention of many researchers from all branches of science. Self-assembly of static structures such as crystals often forms through energy minimization, while dynamic ones need constant energy flow to maintain their state. Most of the studies on self-assembly are limited to static self-assembly, and despite its ubiquity in nature, our comprehensions of dynamic self-assembly are still in its infancy due to lack of experimental settings that can keep the system in its dynamical state. In 2017 a state-of-the-art dissipative (dynamic) self-assembly method was introduced by S. Ilday, and co-workers (Nature Commun., 2017). Here, using this method, we studied the formation of dynamic adaptive colloidal crystals far from equilibrium. We use a femtosecond laser as an energy source to drive a quasi-2D confined colloidal system far from thermodynamic equilibrium, and for the first time, we observed the formation of a rich set of dynamic adaptive colloidal crystals of tens to hundreds of units of polystyrene spheres, which interact through hydrodynamic and hard-sphere interactions. We report formation of periodic 2D Bravais lattices, Moiré patterns, honeycomb lattices and aperiodic quasicrystals. Furthermore, we identify, analyze, and verify some of the key experimental parameters, e.g., physical boundaries, thickness of the liquid film, and the average velocity of Brownian motion, affecting the formation of such a variety of colloidal crystals. We anticipate this study to be a starting point to uncover the physical principles behind the emergence of patterns from simple parts.