Mimicking the rice leaf--from ordered binary structures to anisotropic wettability.

In this paper, we report a method to fabricate a series of surfaces with large-area ordered binary arrays by controllable dewetting. The binary structure arrays consist of an ordered-stripe array and droplet-row array. In order to expand the system, polystyrene (PS) and poly(methyl methacrylate) (PMMA) are introduced in this experiment for investigation in detail. Through adjustment of the polymer solution concentration and the modified underlying pattern on substrate, the surface topographies can be controlled simply. Accordingly, three types of topographies with ordered binary arrays have been obtained by thermal annealing. These unique surfaces mimic the natural rice leaf structurally, which also displays anisotropic wettability for water droplet as natural surfaces. This method points out a new way for the manufacture of functional surfaces.