(383b) Microscopic Gas Diffusion in Hybrid Membranes Composed of Ionenes and Ionic Liquids By NMR

Extensive research in the past decade has brought to light several energy- and cost-effective materials that have shown promising behavior in gas separation processes like CO₂ capture and air separation. Advanced polymer, inorganic, and hybrid membrane materials are a few examples, each with their benefits and limitations. This work focuses on a new class of materials that incorporates the benefits of several structurally diverse materials into a hybrid material platform, called “Doubly-Segmented (DS) Ionenes”. DS ionenes are composed of neutral and ionic segments that are independently synthesized as oligomers and then tethered together with the ability to include free ionic liquid (IL) within the polymer matrix. This study reports the results of the quantification of transport properties of such membranes on different length scales smaller than the membrane thickness. Diffusion measurements were carried out by C-13 pulsed field gradient PFG NMR for light gases such as carbon dioxide and methane. When possible, PFG NMR data are compared with the corresponding transport data from macroscopic permeation experiments performed for the same membranes under the same or similar experimental conditions. The diffusion data obtained for hybrid membranes with added ILs is compared with those in the corresponding IL-free membranes. To our knowledge, this work represents the first microscopic diffusion study of ionenes with or without added ILs.