# Reconfigurable multi-scale colloidal assembly on excluded volume patterns

## TL;DR

Researchers developed a way to create reconfigurable colloidal structures using temperature and patterns, enabling dynamic control over material properties.

## Contribution

A novel method combining thermoresponsive particles and patterned features to reversibly control colloidal assembly structures.

## Key findings

- Colloidal microstructures reconfigure between ordered and disordered states with temperature changes.
- Monte Carlo simulations accurately model the behavior of patterned excluded volume depletion interactions.

## Abstract

The ability to create multi-scale, periodic colloidal assemblies with unique properties is important to emerging applications. Dynamically manipulating colloidal structures via tunable kT-scale attraction can provide the opportunity to create particle-based nano- and microstructured materials that are reconfigurable. Here, we report a novel tactic to obtain reconfigurable, multi-scale, periodic colloidal assemblies by combining thermoresponsive depletant particles and patterned topographical features that, together, reversibly mediate local kT-scale depletion interactions. This method is demonstrated in optical microscopy experiments to produce colloidal microstructures that reconfigure between well-defined ordered structures and disordered fluid states as a function of temperature and pattern feature depth. These results are well described by Monte Carlo simulations using theoretical depletion potentials that include patterned excluded volume. Ultimately, the approach reported here can be extended to control the size, shape, orientation, and microstructure of colloidal assemblies on multiple lengths scales and on arbitrary pre-defined pattern templates.