Towards large-size bulk ZIF-62 glasses via optimizing the melting conditions

Production of large-size, bulk, and bubble-free melt-quenched Zeolitic Imidazolate Framework (ZIF) glasses is a challenge due to the difficulty in up-scaling of the synthesis of the initial ZIF crystals, to the extremely high viscosity at melting point and to their relatively high brittleness. In this work, we optimize the melt-quenching process to increase the size of ZIF-62 glass products and to increase their homogeneity and transparency. By finding the optimum melting time (i.e., <5 min), we succeeded in producing >10 mm large glass samples with a certain degree of transparency and low bubble content, which can be used for mechanical characterizations. We have found the condition (e.g., melting time >30 min) for obtaining ZIF-62 glass foams, which result from partial decomposition during melting. This work provides some information for up-scaling the ZIF glass production.