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Active Colloid Phase Transitions and Living Binary Crystal Formation
Jingyuan Chen1,2, Shaobin Zhuo3, Binglin Zeng1
1Department of Chemistry, The University of Hong Kong, Pokfulam 999077, Hong Kong, China.
ACS Nano
|February 4, 2026
Summary
Photoactive colloids mimic atomic behavior, enabling tunable phase transitions and "chemical reactions" between different colloid types. This research offers a new platform for studying colloidal systems and reaction pathways.
Area of Science:
- Soft Matter Physics
- Materials Science
- Physical Chemistry
Background:
- Colloids serve as model systems (
- meta-atoms
- ) for studying atomic-scale phase behaviors due to their slower dynamics.
- Photoactive colloids offer tunable interactions and dynamics, ideal for emulating atomic lattice phase transitions.
Purpose of the Study:
- To demonstrate how photochemical reactions on active colloids can create an optically tunable hydrodynamic interaction field.
- To achieve controllable phase transitions (zigzag bands, chains, dispersed phases) in colloidal systems.
- To investigate
- chemical reactions
- and phase transitions in colloidal alloys with passive colloids.
Main Methods:
- Utilizing photoactive colloids with on-demand directional interactions and tunable dynamics.
- Employing two sets of illumination to control directional interactions and omnidirectional repulsion.
- Introducing passive colloids to induce inter-species
- chemical reactions
- and form colloidal compounds.
Main Results:
- Demonstrated optically tunable hydrodynamic interaction fields induced by photochemical reactions.
- Achieved controllable phase transitions between zigzag bands, chains, and dispersed phases based on bond orientational order.
- Observed the formation of colloid compounds with defined stoichiometric ratios and emulated their phase transitions.
Conclusions:
- The developed platform bridges active matter physics and solid-state chemistry.
- Provides a versatile tool for studying phase diagrams in colloidal systems.
- Enables optical encoding of
- reaction pathways
- in colloidal alloys.
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