Abstract
Science, 11 Aug 2022, Vol 377, Issue 6607 pp. 768-772 Controlling interfaces of phase separating fluid mixtures is key to creating
diverse functional soft materials. Traditionally, this is accomplished with
surface-modifying chemical agents. Using experiment and theory, we study how
mechanical activity shapes soft interfaces that separate an active and a
passive fluid. Chaotic flows in the active fluid give rise to giant interfacial
fluctuations and non-inertial propagating active waves. At high activities,
stresses disrupt interface continuity and drive droplet generation, producing
an emulsion-like active state comprised of finite-sized droplets. When in
contact with a solid boundary, active interfaces exhibit non-equilibrium
wetting transitions, wherein the fluid climbs the wall against gravity. These
results demonstrate the promise of mechanically driven interfaces for creating
a new class of soft active matter.