Figure 4.

Photochemical reaction-triggered swarming of CPs. (A) Schematic illustration of the swarming of CPs based on diffusiophoresis; (B) AgCl microparticles before and after ultraviolet (UV) illumination (reproduced from [28]); (C) light-controlled reversible expansion–contraction movements of TiO₂–SiO₂ Janus microparticles (reproduced from [29]); (D) transition between schooling and exclusion behaviors of Ag₃PO₄ microparticles (reproduced from [30]); (E) the diffusiophoretic swarming of amino polystyrene (NH₂-PS) CPs induced by UV light (reproduced from [74]). Scale bars, 20 μm (B,D) and 6 μm (E).