Figure 3

Schematic illustration of different sandwich-typed systems (top), POM components assembled on flat substrates (middle), and corresponding optical images (bottom). (a) For hydrophobic flat substrate and superhydrophobic pillar-structured template, the solution is completely extruded from the interspace of two substrates, revealed by no obvious crystals on the flat substrate; (b) For hydrophobic flat substrate and superhydrophilic pillar-structured template, solution mainly fill in the spacing of superhydrophilic pillars but rarely rest on the top of these pillars, which can be demonstrated by a few disordered crystals; (c) For hydrophilic flat substrate and superhydrophilic pillar-structured template, POM solution fills in the top and spacing of the pillars, verified by the rounded and disordered patterns; (d) For hydrophilic flat substrate and superhydrophobic pillar-structured template, well-ordered POM crystal arrays can be observed because the air pocket efficiently restricts the spreading of solution and is benefit for the generation of microdroplets and subsequent POM crystals. Scale bars, 50 µm; scale bars of insert images, 20 µm.