(538c) Radiation-Induced Modifications of Zeolitic Imidazolate Frameworks Membrane Characteristics

Zeolitic imidazolate frameworks (ZIFs) display remarkable flexibility in both their chemical composition and structure. Particularly intriguing are post-synthetic modification (PSM) methods, which offer the ability to precisely adjust MOF structures, enhancing their effectiveness in various applications such as gas storage, molecular separations, and catalysis.

In this presentation, we will introduce the solvent-less PSM approaches we employed, such as electron beam irradiation and nonthermal plasma treatment. These methods have been proven to enhance the CO₂ selectivity of ZIF-8 membranes over other gas molecules within a short treatment time of less than 2 minutes, at the expense of CO₂ permeation. Furthermore, we will describe various ex situ techniques (e.g., X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffraction (GIXD), and electron microscopy) as well as in situ technique of infrared reflection absorption spectroscopy (IRRAS) used in collaboration with Brookhaven National Lab to provide insights into the modifications in the materials surface chemistry and their correlation with the altered membrane properties.

Moreover, we will discuss the recently obtained results of tuning the permselectivity of ZIF-8 membranes while leaving CO₂ permeance almost unaffected through X-ray exposure. Alongside materials characterizations and analysis based on the aforementioned techniques, we estimated the improvement in membrane separation performance resulting from X-ray irradiation. This estimation was done by calculating the separation index ratio (SIR), which is the ratio of the separation index (SI) after X-ray treatment to the value determined for the pristine membrane.