Highly ordered, hexagonally patterned poly(methyl methacrylate) (PMMA) thin film is successfully fabricated using an improved phase separation method. A mixture of chloroform and methanol, which is used as a volatile solvent/nonsolvent pair, effectively controls the surface morphology and sensitively determines the ordered pattern. In particular, the methanol accumulation, which induces the formation of a gel-like protective layer and enhances the lateral capillary force, is crucial in the formation of the highly ordered hexagonal pattern even when using a nonpolar polymer such as PMMA. The convergence of cost-effective and large-scale production of highly ordered micropatterned film has wide potential for application, and it can enable new prospects for the commercialization of future high-tech devices that require specific multifunctionality.

Inspired by treefrog's toe pads that show superior frictional properties, herein, an industrially compatible approach is reported to make an efficient dielectric tribosurface design using customizable nonclosepacked microbead arrays, mimicking the friction pads of treefrogs, in order to significantly enhance electrification performance and reliability of triboelectric nanogenerator (TENG). The approach involves using an engineering polymer to prepare a highly ordered large-area concave film, and subsequently the molding of a convex patterned triboreplica in which the concave film is exploited as a reusable master mold. A natureinspired TENG based on the patterned polydimethylsiloxane (PDMS) paired with flat aluminum (Al) can generate a relatively high power density of 8.1 W m −2 even if a very small force of ≈6.5 N is applied. Moreover, the convex patterned PDMS-based TENG possesses exceptional durability and reliability over 25 000 cycles of contact-separation. Considering the significant improvements in power generation of TENG; particularly at very small force, together with cost-effectiveness and possibility of mass production, the present methodology may pave the way for large-scale blue energy harvesting and commercialization of TENGs for many practical applications.

Thin films of bio-compatible poly(lactic acid) with highly ordered hexagonal patterns were successfully fabricated under normal ambient conditions without using any surfactant via an improved phase separation method. The patterned surface was successfully applied to fabricate silicon/copper dome-patterned electrodes for high-performance hybrid capacitors.

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