(400ai) Liquid Diffusion in CMS-Based Mixed Matrix Membranes By PFG NMR

Carbon molecular sieve (CMS)-based mixed matrix membranes (MMMs) are promising materials for liquid separations, as they combine the superior separation performance of CMS particles with favorable mechanical properties of polymers. Previous work on metal-organic framework (MOF) fillers confined in high bulk modulus polymers, such as Torlon^®, has demonstrated that confinement can substantially alter the intrinsic transport properties of filler particles. Based on these studies, it was concluded that polymer confinement of filler particles can reduce their structural flexibility, thereby leading to a change in transport properties compared to unconfined filler particles. Building on these insights, our current work investigates how introducing CMS particles in a polymer like Torlon^® modifies their transport behavior. To investigate the influence of confinement on diffusion, we employ pulsed field gradient (PFG) nuclear magnetic resonance (NMR) to measure the intra-particle self-diffusion of single-component liquid sorbates, such as methanol and xylene isomers, at microscopic length scales. Using PFG NMR, we compare intra-particle self-diffusion rates of different liquid sorbates in reference samples of loosely packed CMS particles with those in the CMS-based MMMs prepared using CMS filler particles from the same batch as the reference sample. This comparison will quantify the impact of polymer confinement on the transport properties of CMS. All diffusion data will be presented for different temperatures and displacement length scales.