(244a) Dynamic Pathways in Reconfigurable Anisotropic Colloidal Assembly

We report the reconfigurable assembly of different shaped anisotropic colloidal particles including dynamic pathways between different states. Assembled configurations include a variety of liquid, liquid crystalline, crystalline, and glassy states with novel and technologically useful multifunctional properties. Microscopy and computer experiments are performed using AC electric fields to control the quasi-two dimensional assembly of disks, ellipses, squares, rectangles, rhombuses, and other curved/stretched variants of these shapes. By tracking particle positions and orientations, we compute in real-time a number of order parameters based on local symmetries within configurations; we then use order parameters vs time as reaction coordinates to capture stochastic dynamic pathways between states. For the specific case of rectangular prism particles with rounded corners, we demonstrate dynamic reconfiguration pathways: (1) between stable fluid, nematic, and crystalline states, (2) temporarily sampling metastable binematic and string-fluid states, (3) passing through transient tetratic and smectic states, and (4) navigating around dynamically arrested glass states. By dynamically changing AC electric field amplitude and frequency, reconfiguration rates are optimized by jumping between free energy landscapes that control assembly pathways, which we show is orders of magnitude faster than diffusion limited evolution on a single landscape at fixed conditions. Our results demonstrate the ability to control the dynamic assembly of diverse microstructures of anisotropic particles to enable previously unattainable particle based materials and devices exploiting their reconfigurable properties.