Albert Xiuyuan Wu

Sorption in glassy polymer membranes is commonly modeled with the dual‐mode sorption (DMS) model. Fitting the DMS model to sorption isotherms presents challenges, as multiple parameter sets may prove satisfactory. This work presents pyDMS, an open‐source Python package for the computation of DMS parameters obtained via a physics‐informed constrained optimization procedure, incorporating linear free energy relationships (LFERs) and van't Hoff constraints. Here, pyDMS is demonstrated by recomputing DMS parameters and sorption energetics from previously published isotherms of seven glassy polymers. Nonsystematic deviations occur between the DMS parameters obtained from constrained and unconstrained optimizations. These deviations become apparent when the parameters are constrained by theoretically anticipated sorption thermodynamics. pyDMS is used to rapidly compute mixed‐gas sorption isotherms and sorption selectivities in PIM‐1 for a 20/80 / molar mixture. Computation of energetics and sorption selectivities elucidates the importance of error propagation in DMS optimization.

Reverse osmosis (RO) and nanofiltration (NF) processes are considered “best available technologies” by the US Environmental Protection Agency for perfluoroalkyl and polyfluoroalkyl substance (PFAS) remediation from water. While these processes are industry standard for applications such as desalination, commercial membranes are typically tailored to said applications, so different membrane products may show differing PFAS rejection behavior based on proprietary manufacturing methods or surface modifications. Additionally, there are limited studies reporting rejection trends of ultrashort‐chain (USC) compared to short‐chain (SC) and long‐chain (LC) PFAS. This work benchmarks a total of 13 commercial RO or NF membranes for eight PFAS, spanning all size classes, under standardized conditions for rejection performance. A comparison of overall PFAS rejection across the membranes showed statistically significant differences in performance, indicating that membranes do not uniformly reject PFAS equally and highlighting the role of membrane chemistry on performance. A strong positive correlation between measured salt rejection and overall PFAS rejection was found. Lastly, USC and SC species were found to have similar rejection while LC species showed significantly higher rejection. These findings emphasize the importance of membrane selection when designing a system for PFAS remediation and provide new insight into PFAS rejection behavior relative to other species and salts.

Pure-gas sorption and mixed-gas transport properties of six functionalized PIM-1 variants were systematically investigated to study the role of CO ₂ affinity and polymer chemistry on competitive sorption.

Gas‐separation polymer membranes display a characteristic permeability–selectivity trade‐off that has limited their industrial use. The most comprehensive approach to improving performance is to devise strategies that simultaneously increase fractional free volume, narrow free volume distribution, and enhance sorption selectivity, but generalizable methods for such approaches are exceedingly rare. Here, we present an in situ crosslinking and solid‐state deprotection method to access previously inaccessible sorption and diffusion characteristics in amine‐functionalized polymers of intrinsic microporosity. Free volume element (FVE) size can be increased while preserving a narrow FVE distribution, enabling below‐upper bound polymers to surpass the H₂/N₂, H₂/CH₄, and O₂/N₂ upper bounds and improving CO₂‐based selectivities by 200 %. This approach can transform polymers into chemical analogues with improved performance, thereby overcoming traditional permeability–selectivity trade‐offs.

Gas‐separation polymer membranes display a characteristic permeability–selectivity trade‐off that has limited their industrial use. The most comprehensive approach to improving performance is to devise strategies that simultaneously increase fractional free volume, narrow free volume distribution, and enhance sorption selectivity, but generalizable methods for such approaches are exceedingly rare. Here, we present an in situ crosslinking and solid‐state deprotection method to access previously inaccessible sorption and diffusion characteristics in amine‐functionalized polymers of intrinsic microporosity. Free volume element (FVE) size can be increased while preserving a narrow FVE distribution, enabling below‐upper bound polymers to surpass the H₂/N₂, H₂/CH₄, and O₂/N₂ upper bounds and improving CO₂‐based selectivities by 200 %. This approach can transform polymers into chemical analogues with improved performance, thereby overcoming traditional permeability–selectivity trade‐offs.