Micropatterned thin films have received increased interest in the past few years. Besides preparation by conventional lithography, self-assembly of materials around a template can be used for patterning. Recently a method that utilizes the condensation of micrometer-size water droplets on solutions of block copolymers was reported for the preparation of ordered micrometer-size honeycomb structures. Here we show that the formation of honeycomb-like porous films is a general method that can be used for patterning many materials, e.g., block copolymers, amphiphilic polyion complexes, organic/inorganic hybrids, and homopolymers, such as polystyrene. Stabilization of water droplets is indispensable for regular pattern formation.

This report describes the simple preparation of superhydrophobic and lipophobic surfaces by self-organization. Microporous polymer films of a fluorinated polymer with hexagonally arranged pores were prepared by casting from solution under humid conditions. Hexagonally packed water microdroplets were formed by evaporative cooling on the surface of the casting solution. After solvent evaporation, a honeycomb-patterned polymer film was formed with the water droplet array acting as a template; the water droplets themselves evaporated soon after the solvent. Two porous polymer layers were stacked vertically, separated by pillars at the hexagon vertexes. After peeling off the top layer using adhesive tape, a pincushion-like structure was obtained. Here, we show that superhydrophobic behavior was achieved, with the maximum contact angle, 170 degrees, observed using these pincushion structures. Theoretical calculations fit the experimental results well. The lipophobic properties of the films are also discussed.