Condensation-assisted assembly of large 2D colloidal crystals

We examined the reorganization of polystyrene microparticles randomly deposited on a substrate into a large bi-dimensional colloidal crystal. The condensation–evaporation process used for this purpose is based on an open-air system. This configuration ensures on one hand the controlled formation of a continuous water film and on the other hand evaporation gradients at the origin of the fluid flows packing the microparticles into a compact assembly (colloidal crystal). The growth of the crystal is discussed on the basis of the microparticle–substrate interactions and the thickness of the condensed water film.