Mechanistic insights into the deformation and degradation of a 2D metal organic framework

Abstract

2D metal-organic frameworks (2D-MOFs) materials can be subjected to various modes of mechanical stresses and strains in a wide range of applications, for which their mechanical properties are critical to reach practical implementations. Despite the rapid developments focused on the preparation of ultrathin 2D-MOF materials, very little is known about their mechanical and degradation behavior. Here, we use the established 2D-MOF PdTCPP-Cu (NAFS-13) as model system, to introduce the Langmuir–Blodgett (LB) technique, combined with interfacial rheology, as a novel in situ method for direct determination of the in-plane Young’s modulus by simultaneously measuring the 2D shear and compression moduli of a 2D-MOF formed at the air-water interface. Furthermore, it can be used to evaluate mechanistic models describing the degradation kinetics of 2D MOFs. To provide a deeper understanding of the factors that determine the Young’s modulus observed in such a set up, we carried out nanoindentation measurements and molecular dynamics (MD) simulations based on classical force fields. This protocol allows us to gain mechanistic insights into the impact of structural defects, temperature, tensile and compression stress on the Young’s modulus of 2D MOFs.