Nanostripe patterning of glass surface by nanoimprint using self-organized oxide mold

We investigated nanoscale surface modifications of silicate glass plates by applying a thermal nanoimprint technique, in which self-organized nanopattern molds of sapphire (α-Al2O3 single crystal) wafer were used. Nanopatterns of the sapphire mold exhibited regularly arranged straight atomic-steps with a uniform height of 0.2 nm and atomically flat terraces about 80 nm in width. We succeeded in forming subnanometer-stepped surfaces of glass. By pressing the glass plate over the mold and then slowly cooling (3 °C/min), a three-dimensional nanostriped pattern (periodic distance of 60–85 nm and peak-to-valley height of 8 nm) was obtained on the glass plate. Softening behavior of the nanopatterned glass morphology was observed at temperatures about 20 °C lower than the glass transition temperature of the bulk glass. The Vickers hardness of the nanostriped glass was estimated to be higher than that of non-patterned glass, and the surface of the nanostriped glass was more hydrophobic than that of non-patterned glass.