Macroscopic, Hierarchical, Two-Dimensional Self-Assembly.

By tailoring capillary interactions at a fluid-fluid interface, a hierarchical two-dimensional self-assembly of hexagonal millimeter-sized poly(dimethylsiloxane) plates has been demonstrated (see picture). The strength and direction of capillary forces between plates was controlled by patterning of the surfaces of the plates to be hydophobic or hydrophilic. The thick lines indicate hydrophobic faces whose mutual attraction forms the basis of capillarity.