Micro-optical elements from optical-quality ZIF-62 hybrid glasses by hot-imprinting

Hybrid glasses derived from meltable metal-organic frameworks (MOFs) promise to combine the intriguing properties of MOFs with the universal processing ability of glasses. However, shaping of hybrid glasses in their liquid state has been elusive thus far. Here, we present optical-quality glasses derived from the zeolitic imidazole framework ZIF-62 in the form of cm-scale objects. These allow for in-depth studies of optical transparency and refraction across the ultraviolet to near-infrared spectral range. Fundamental viscosity data are reported using a ball penetration technique, and subsequently used to demonstrate the fabrication of micro-optical devices by thermal imprinting. Using 3D printed fused silica templates, we show that concave as well as convex structures can be obtained at high precision by remelting the glass without trading-off on material quality. This paves a route towards melt-processing of MOF-derived glasses on a scale relevant for real-world applications and enables multifunctional micro-optical devices combining the gas uptake and permeation ability of MOFs with the optical functionality of a glass.