Self-Assembled Arrays of Non-Coalescent Water Drops

Condensation figures form over polymer dissolved in volatile solvent exposed to a stream of moist air. These patterns are hexagonally symmetric and they comprise of non-coalescent and nearly monodisperse water drops. Typical condensation figures have a range of drop sizes, resulting from the nucleation, growth and coalescence of different generations of water drops. In this study, we image the pattern formation over evaporating polymer solutions. We observe that rafts of growing drops evolve into a highly organized two dimensional lattice, which eventually evaporate away as well, templating ordered arrays of holes in polymer films. We derive the analytical and modeling framework for determining the key kinetic parameters that control the typical length scales and timescales of droplet growth, non-coalescence and assembly.