Strongly metastable assemblies of particles at liquid interfaces.

The self-assembly of floating particles is a widely observed phenomenon. Ideally, rafts of identical floating spheres or cylinders should assemble in a closed-packed fashion. However, rafts are observed to exhibit large and various defects, and we show that the conjunction of lateral liquid bridges between particles and contact angle hysteresis freezes the rotation of particles around their neighbors, a mechanism that generates imperfect rafts. Conversely, we demonstrate how this capillary bond can be exploited to sculpt 2D aggregates far from equilibrium that are persistent.