Addition of modifiers in network glasses, e.g., silicates, is generally associated with depolymerization 1 . This results in a monotonic change of glass properties with the modifier content, such as decreasing Tg with increasing modifier content 1 . To study if this is also the case for the present samples, we have prepared glassy mixtures of each of the three ZIFs co-melted with bImCl for R values of 0.25, 0.5, 0.75, and 1.0. Generally, higher temperatures are required to fully melt the system for lower values of R (see XRD results in Supplementary Fig. ), but we note that all samples reach a fully molten state at ~300-360 °C (see photographs of recovered samples in Supplementary Fig. ). Using FDSC, we find a monotonic decrease in Tg with increasing modifier content, in good resemblance with other network glasses (see comparison of varying R on Tg in Fig. ,d and raw data in Supplementary Fig. and Table ). Notably, we observe that the modified glasses are prone to a permanent increase in Tg upon subsequent heating (>300 °C) for few minutes or even seconds (Supplementary Fig. ). An effect we assign to evaporation of Im and bIm species coming from both the network and added modifier salt (see Supplementary Text). Considering the mechanical properties, the Vicker's hardness of the ZIF-4-bImCl and ZIF-62-bImCl (R=1.0) glasses is lower (~0.35 GPa, Supplementary Fig. ) than that of the unmodified ZIF glasses (~0.6 GPa) .