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Polymer‐based membrane technology holds immense promise for CO2 separation. However, it faces persistent challenges, including the high CO2 pressure‐induced plasticization and permeability‐selectivity trade‐offs, which significantly hinder the development of polymeric membranes. To tackle this issue, we synthesized a novel polyimide 6FDA‐DAT:DABA(6FDD) containing triptycene and carboxylic groups. Upon de‐carboxylation induced cross‐linking, the membrane demonstrated a simultaneous enhancement of gas permeability and selectivity. Specifically, compared to the uncross‐linked 6FDD, the 400°C‐24 h cross‐linked membrane exhibited a remarkable increase in CO2 permeability by 177% (93.1 Barrer) and a significant rise in CO2/CH4 selectivity by 47% (57.5), reaching the CO2/CH4 upper bound. More importantly, the cross‐linked membrane displayed vastly improved CO2 plasticization resistance, withstanding up to 42 bar of CO2 feed pressure. The design of decarboxylated cross‐linked membranes in this work paves the way for creating high‐performing and plasticization‐resistant membranes with potential applications in high‐pressure CO2 separations. [ABSTRACT FROM AUTHOR]

For the sake of water and energy conservation, development of latent heat cooling and thermal storage systems that minimize water consumption and operate with higher efficacy than their water-driven counterparts is a crucial task. Phase change materials (PCMs) present a potential solution, but their integration into real-world systems abounds with scientific challenges such as material toxicity, flammability, low thermal performance and lack of tunable phase-change temperatures. In this study we report on a first-in-class nanocomposite PCM that leverages non-flammable, non-toxic, high latent heat sugar alcohols (SAs) encapsulated within easy-to-synthesize zeolitic imidazolate framework (ZIF) crystals. We also outline a practical route for surface functionalization with hydrophilic and hydrophobic moieties. The SA@ZIF composites display suppressed phase-change temperatures which, together with alterable surface functionality, broadens their applicability to a plethora of working environments. Direct synthesis of the SA@ZIF composite generates nanoconfined SAs with phase-change temperatures as low as 19.8 °C and latent heats as high as 285 J g−1. This nanoconfinement-induced thermal phenomenon is conserved even after functionalization of the SA@ZIF crystal surface. We believe this study will lay the groundwork as a platform for next generation high performing, tunable PCMs to aid in the realization of waterless cooling systems. [ABSTRACT FROM AUTHOR]

Membrane separation technology provides substantial savings in energy and cost for molecular separations in chemical industry, ideally complementing conventional thermally driven separation approaches. However, current membranes are subject to limitations, primarily lying in the Robeson permeability–selectivity upper bound limits. In this study, hydroxy metal‐organic framework (MOF)/polyimide mixed‐matrix membranes are found to enable high separation performance for applications including CO2 capture and hydrogen purification while offering enhanced compatibility with state‐of‐the‐art membrane‐manufacturing processes. The mixed‐matrix membranes exceed the present Robeson upper bounds with H2 and CO2 permeabilities of 907 and 650 Barrers, respectively and H2/CH4 and CO2/CH4 selectivities of 45 and 32, respectively. The unparalleled performance results from intimate interactions at the boundary of the hydroxy MOFs and carboxylic polymers through strong hydrogen bonds. The principle of design opens the door to highly permeable membranes with synergistic compatibility with established membrane manufacturing platforms for energy‐efficient molecular separations. [ABSTRACT FROM AUTHOR]

Abstract: High-performance ester-crosslinked hollow fiber membranes were evaluated for sensitivity to aggressive hydrocarbon and water impurities. The hollow fiber samples show improved separation productivity and hydrocarbon-induced antiplasticization resistance under extremely challenging feed conditions in comparison to previously reported cases. The CO2 permeance was improved from 10GPU to 50GPU with a CO2/CH4 selectivity of 28 in testing at an 800psi 50/50 CO2/CH4 feed with 1000ppm (molar) toluene, 35°C. Moreover, membrane samples with different skin layer thicknesses show significantly different sensitivities to toluene. The thinner skinned samples are hypothesized to have higher fractional free volume (FFV) and hence show more tendency to antiplasticize when exposed to impurities as compared to thicker skinned samples. The high separation performance of crosslinked hollow fibers was fully recovered after removing the high-level contaminants, including toluene and heptane, and showed negligible changes over 100h exposure to a 600psi 50/50 CO2/CH4 feed with 750ppm toluene, indicating a strong stability against contaminants. Furthermore, exposure to 101ppm (molar) water impurity did not cause an apparent subsequent change in the separation properties. The excellent properties in the presence of hydrocarbon and water contaminants demonstrate that ester-crosslinked hollow fiber membranes are attractive for natural gas purification, even under more aggressive operating conditions. [Copyright &y& Elsevier]

High-performance ester-cross-linkablecomposite hollow fibers were developed through simultaneous spinningof 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA)based polyimide and Torlon (registered trademark of Solvay Polymers)solutions. The core layer polyamide-imide polymer, Torlon, demonstratesexcellent adhesion with cross-linkable 6FDA-based polyimide duringspinning and ester-cross-linking. Torlon also shows superior thermalstability after cross-linking while maintaining the open substructureof the Torlon core layer. The resultant cross-linked composite hollowfibers show a CO2permeance of 40 GPU with a CO2/CH4selectivity of 39 in testing at 100 psi with 50/50CO2/CH4feed, 35 °C. The cross-linked compositehollow fibers also show high separation performance in the presenceof high-level toluene contaminants up to 1000 ppm, suggesting thatcross-linked composite hollow fibers are viable under realistic operationconditions. The high natural gas separation performance and significantlyreduced cost of hollow fiber formation provides a significant advancementin the state of the art for natural gas separations. [ABSTRACT FROM AUTHOR]

Membranes have seen a growing role in mitigating the extensive energy used for gas separations. Further expanding their effectiveness in reducing the energy penalty requires a fast separation process via a facile technique readily integrated with industrial membrane formation platforms, which has remained a challenge. Here, an ultrapermeable polyimide/metal‐organic framework (MOF) hybrid membrane is reported, enabling ultrafast gas separations for multiple applications (e.g., CO2 capture and hydrogen regeneration) while offering synthetic enhanced compatibility with the current membrane manufacturing processes. The membranes demonstrate a CO2 and H2 permeability of 2494 and 2932 Barrers, respectively, with a CO2/CH4, H2/CH4, and H2/N2 selectivity of 29.3, 34.4, and 23.8, respectively, considerably surpassing the current Robeson permeability–selectivity upper bounds. At a MOF loading of 55 wt%, the membranes display a record‐high 16‐fold enhancement of H2 permeability comparing with the neat polymer. With mild membrane processing conditions (e.g., a heating temperature less than 80 °C) and a performance continuously exceeding Robeson upper bounds for over 5300 h, the membranes exhibit enhanced compatibility with state‐of‐the‐art membrane manufacturing processes. This performance results from intimate interactions between the polymer and MOFs via extensive, direct hydrogen bonding. This design approach offers a new route to ultraproductive membrane materials for energy‐efficient gas separations. [ABSTRACT FROM AUTHOR]