Elucidation of the Interfacial Adhesive Mechanism in Zeolitic Imidazolate Framework-67-Based Adhesives

Metal–organic frameworks (MOFs) have attracted significant attention because of their diverse functionalities; nevertheless, despite their considerable potential, their use as bonding materials remains largely unexplored. One of the major reasons for this is the limited understanding of the bonding mechanisms at the interface with substrates. In this study, we investigate the interfacial bonding mechanism of ZIF-67-based adhesives for forming high-strength joints with copper substrates. Nanostructural analyses reveal the formation of an amorphous interfacial region enriched in oxygen and depleted in cobalt, suggesting a compositional change near the substrate. Electron energy loss spectroscopy (EELS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirm the presence of a copper–2-methylimidazole coordination polymer, which is proposed to serve as an interfacial phase that facilitates strong adhesion. These findings provide a foundational understanding of MOF-based adhesion and will facilitate the development of synthesis guidelines for MOF adhesives optimized for different substrate metals.