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

Abstract

Abstract2D 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.

Mechanical Properties of Modulative Undulating Layers in Two-Dimensional Metal–Organic Frameworks

“…2D metal–organic frameworks (2D-MOFs) are modern layered materials that are considered to have applications in various fields. ,− In addition to many synthetic efforts of various researchers for 2D-MOFs to explore their high functionalities, their functionality changes upon mechanical stimuli have sometimes been investigated by preparing free-standing membranes and flakes . However, reports on the mechanical properties of 2D-MOFs remain limited. ,− In particular, the systematicity of anisotropic mechanical properties via chemical tuning of layered structures is largely unexplored, even though the high designability of layered structures using molecular components is an advantage of 2D-MOFs over other 2D materials.…”