Multistate Dynamic Pathways for Anisotropic Colloidal Assembly and Reconfiguration

Abstract

We report the controlled interfacial assembly and reconfiguration of rectangular prism colloidal particles between microstructures of varying positional and orientational order including stable, metastable, and transient states. Structurally diverse states are realized by programming time dependent electric fields that mediate dipolar interactions determining particle position, orientation, compression, and chaining. We identify an order parameter set that defines each state as a combination of the positional and orientational order. These metrics are employed as reaction coordinates to capture the microstructure evolution between initial and final states upon field changes. Assembly trajectory manifolds between states in the low-dimensional reaction coordinate space reveal a dynamic pathway map including information about pathway accessibility, reversibility, and kinetics. By navigating the dynamic pathway map, we demonstrate reconfiguration between states on minute time scales, which is practically useful for particle-based materials processing and device responses. Our findings demonstrate a conceptually general approach to discover dynamic pathways as a basis to control assembly and reconfiguration of self-organizing building blocks that respond to global external stimuli.

Effect of Particle Composition on Dielectrophoretic Co-Assemblies around Topographic Features: Experiment and Theory

“…Colloidal particles can be assembled in applied electric fields to generate tunable, dynamic superstructures able to be annealed or reconfigured by changes in the applied field. − For example, colloidal crystals, − chains, − nanowire lattices, , and other structures have been generated using applied AC fields. − Such assemblies can be reconfigured in real time by changing applied field conditions, enabling a particle based, AC field-tunable optical response. For example, core–shell microparticle assembly for tunable metamaterials, switchable mid-IR broadband polarizers, reconfigurable scattering masks, field-responsive random lasers, gradient index lenses, and various surface-enhanced Raman scattering techniques − have been demonstrated based on controlling the orientation and/or local number density of various particle types.…”