IMPACT OF OXIDATION OCCURREDDURING DESOLVATIONPROCESS ON THE MELTING PROPERTIES OF ZIF 62

摘要

Zeolitic imidazolate frameworks (ZIFs), as a family of metal-organic frameworks (MOFs) which possess nanoporous structure, have been investigated intensively in the past two decades for a variety of applications. Recently, a subgroup of ZIFs including ZIF-62 (Zn(Im2-xbImx)) has been demonstrated to form a new kind of glasses by melt-quenching, indicating that some ZIFs possess excellent melting properties. In this paper, ZIF-62 crystals were synthesized using solvothermal synthesis method. The impact of oxidation occurred in desolvation process on the melting properties of ZIF-62 was investigated by preheating the ZIF-62 samples under different conditions. From the results of Tm and Tg obtained from differential scanning calorimeter measurement (DSC), we found that the solvent removal of ZIF-62 in inert environment prior to the melting does not cause the structural collapse; however, oxidation occurred during the desolvation process under air atmosphere has a significant effect on the melting attributes of ZIFs. This result shows that the framework structure of ZIFs is quite sensitive to oxygen, giving us an enlightenment that preventing oxidation during pretreatment to remove solvent is crucial to the formation of ZIFs glasses.