(496e) Physical Aging of Defect-Free Functionalized Asymmetric PIM Hollow Fiber Membranes

Polymer hollow fibers are an important membrane format for enhancing energy-efficient gas separations and organic solvent nanofiltration. Compared to traditional flat sheet membranes, these fibers offer advantages such as higher surface-area-to-volume ratios (up to 10³ m²m^−3), thin selective layers, and improved mechanical stability. However, despite their versatility, polymer membranes face challenges in industrial deployment due to the permeability-selectivity trade-off, as per the Robeson upper bound. To address this, polymers with inefficient packing structures and high fractional free volume, known as polymers of intrinsic microporosity (PIMs), have been developed. Among these, PIM-1 can be modified post-synthetically via solid-state functionalization to enhance gas separation performance for specific gas pairs by targeting its nitrile groups. Nevertheless, membranes made from glassy polymers suffer from physical aging, wherein polymer chains relax towards equilibrium, decreasing the material’s fractional free volume over time, thus impacting membrane performance. This study focuses on synthesizing high molecular weight PIM-1 at a large scale for hollow fiber spinning, followed by solid-state functionalization to produce an amine-functionalized derivative (PIM-NH₂). The aim is to investigate the effects of hydrogen bonding and chain mobility on the physical aging of hollow fibers. Results indicate that both types of PIM fibers experience accelerated aging compared to dense films, with PIM-1 fibers showing increased selectivity as permeability decreases over time, likely due to chain alignment during spinning. This research provides valuable insights into the physical aging and long-term performance of PIM-based hollow fibers, representing a comprehensive aging study conducted on such fibers spun from microporous organic polymers.