Surface Engineering Layered Metal–Organic Framework to Enhance Processability and Stability in Water

Abstract

Despite considerable advancements of metal–organic frameworks (MOFs), the practical implementation of MOFs is still hindered by issues of stability and processability. In this work, we sought to overcome these difficulties through surface engineering. As a proof of concept, we subjected ZIF‐L with a unique layered crystal morphology to a shell‐ligand exchange reaction. This resulted in the partial replacement of 2‐methylimidazole by benzimidazole as the linker in the framework on the outer surface of the crystals, thereby changing the surface of the ZIF‐L crystal from hydrophilic to hydrophobic. The engineered ZIF‐L (hereafter referred to as Benz‐ZIF‐L) formed a stable dispersion in the nonpolar solvent, hexane. The suspension of Benz‐ZIF‐L in hexane was applied via spin coating to a porous substrate of poly(vinylidene fluoride) (PVDF), resulting in a thin film of high density. In contrast, the application of a suspension of pure ZIF‐L in the same manner did not result in the formation of a thin film. Benz‐ZIF‐L also exceeded pure ZIF‐L with regard to hydrothermal stability and acid/base resistance.

Heterogeneous ZIF-L membranes with improved hydrophilicity and anti-bacterial adhesion for potential application in water treatment

“…Besides, post-modication with hydrophobic ligands (i.e. benzimidazole) was conducted, 53 and water stability of modied membranes can be improved as expected (Fig. S13 †).…”

“…In order to improve the water stability of as-prepared ZIF-L membranes, a post-ligand-exchange reaction was conducted according to the previous work. 53 In detail, a chemical solution was made by dissolving benzimidazole (0.5 g) and sodium acetate (0.35 g) in methanol (50 mL). The above prepared ZIF-L membranes were vertically placed into the solution and kept standing at room temperature for 24 h. The modied membranes were then washed with methanol for 2 times to completely remove any free 2-methylimidazole and free benzimidazole.…”

Highly dispersive PEI-modified CDs@ZIF-L dual-emitting fluorescent sensor for detecting metal ions

“…One is to use a shell ligand exchange reaction to change the surface of layered ZIF from hydrophobic to hydrophilic. 10,11 The other is a seeding method that achieves oil-repellent performance by coating the surface, such as ZIF-8 lm-coated stainless steel meshes (ZFCMs). 12 In a ZIF-8based sensor, polyethylene glycol (PEG), polyethyleneimine (PEI), or other polymer compounds can be used owing to their high hydrophilicity.…”

Brine available two-dimensional nano-architectonics of fluorescent probe based on phosphate doped ZIF-L for detection of Fe3+

“…Thus, to improve the stability of ZIFs in aqueous solutions, various methods have been developed. One such method includes using a shell-ligand-exchange reaction to transform the interior surface of layered ZIFs from hydrophilic to hydrophobic [ 31 , 32 ].…”