Geometric Routes to Activity in Soft Matter

Active matter is often defined by internally driven constituents, but many soft systems become effectively active through their interaction with evolving geometry, order, constraints, and boundaries. In this talk, I will discuss recent work exploring how couplings between material order and shape change can generate directed motion, assembly, and function—without activity at the level of individual particles.

I will focus on three examples drawn from liquid-crystalline and soft composite systems. The first example shows how nanoparticles can be transported, concentrated, and assembled by a moving liquid-crystal phase boundary, effectively “surfing” gradients in order during a phase transition. Second, I show how process emerges in shape-changing emulsion droplets, membranes, and shells whose mechanical response emerges from competition between elasticity, geometry, and confinement, leading to robust nonequilibrium morphologies. Finally, I will highlight computational approaches that make it possible to systematically explore and design such driven shape–order couplings.