Shape evolved structured liquids driven by active particles*

Shape evolution enabled dynamic biological behaviors of cells and organisms, such as migration, reconfiguration and division, are driven by internal active matters. Production of synthetic active system that can mimic such dynamic behaviors of natural system remains challenge. Water-water interfaces or lipid bilayers with ultralow interfacial tension can be locally deformed by microtubules or self-propelled particles, but the deformed shapes will relax upon the energy dissipation of active matter and will not retain. Activity of these active matters relies on the concentration gradient of fuel. Thus, the manipulation of shapes lacks instant switch control. Emulsion droplets and lipid vesicles internally powered by active components can only realize shape changes and spontaneous motions at the micrometer scale level, which limit their applications, such as design of robotic systems at the millimeter scale or macroscale level. Here we develop a shape-evolved structured liquid driven by encapsulated active ferromagnetic particles to address all these limitations. Our fully synthetic system exhibits flexible tunability. The interfacial membrane assembled from oppositely charged polystyrene sulfonate (70k) and mono-amine-functionalized polyhedral oligomeric silsesquioxane (POSS-NH2) is reconfigurable. The interfacial tension of structured membrane is easily tuned by PH and concentration of surfactants within 4 orders of magnitude, which in turn adjusts the hardness of the wall (stop and go). The activity of ferromagnetic particles can also be instantly controlled by the strength and frequency of AC magnetic field. The tunable collective behaviors of active components and reconfigurable membrane give rise to the on-demand shape evolution, which enable the directional migration, division and reconfiguration of structured liquids at multiscale level. This strategy would provide a route to a new class of biomimetic, reconfigurable, and responsive materials, delivering mechanical responses unlike those of conventional materials and highlighting the design of autonomous synthetic machines powered by active matter.