Mass production of moth-eye structured films and fabrication of micro–nano hybrid structures using moth-eye patterns

Moth-eye structures are biomimetic nanostructures with anti-reflective properties. In this study, a fabrication method based on oxygen ion beam irradiation of glassy carbon (GC) was developed to produce moth-eye structures. GC is a carbon-based material, and oxygen ion beam irradiation induces ion-beam-driven nanoscale surface modification, resulting in the spontaneous formation of conical nanostructures characteristic of moth-eye structures. Based on this principle, a scale-up fabrication process was established. A roll mold was first prepared by sputter-depositing GC onto a roll surface, followed by oxygen ion beam irradiation using reactive ion etching equipment. The fabricated moth-eye roll mold was then installed in a roll-to-roll ultraviolet nanoimprint lithography (RTR UV-NIL) system to transfer the structure onto a film surface. The moth-eye-structured film exhibited low reflectance (0.1% in the visible wavelength range) and high transparency (94%). Continuous transfer was achieved on films with a width of 1.5 m, demonstrating the feasibility of mass production of moth-eye-structured films. These films are suitable for applications such as display windows, showcases, and digital signage. To further enhance functionality, a micro–nano hybrid structure was fabricated by exploiting the moth-eye structure. This process involved forming a micropattern by applying a hydrophilic photoresist to the moth-eye surface, filling the structure with a water-repellent UV-curable resin, UV irradiation, and subsequent release of the micropattern to generate micron-scale hydrophilic regions within a water-repellent moth-eye structure. As a result, an adhesive, water-repellent surface exhibiting the rose petal effect was obtained, which was also effective for harvesting water from fog.