Programmable Dynamic Shapes with a Swarm of Light-Powered Colloidal Motors.

We report robust control over the dynamic assembly, disassembly, and reconfiguration of light-activated molybdenum disulfide (MoS2 ) colloidal motor swarms with features not possible in equilibrium systems. A photochemical reaction produces chemical gradients across the MoS2 colloidal motors to drive them to move. Under illumination of a gradient light, these colloidal motors display a positive phototactic motion. Mesoscale simulations prove that the self-diffusiophoresis induced by the locally consumed oxygen gradient across MoS2 colloidal motors dominates the phototactic process. By programming the structured illumination, the collective migration and well-defined shapes of colloidal motor swarms can be externally regulated. The successful realization of programmable swarm transformation of colloidal motors like the emergent behaviors of living systems in nature provides a direct proof-of-concept for active soft materials and systems, with adaptive and interactive functions.