2 research outputs found

    Effects of Spinning Temperature on the Morphology and Performance of Poly(ether sulfone) Gas Separation Hollow Fiber Membranes

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    In this study, we demonstrated that poly­(ether sulfone) (PES) hollow fiber membranes with almost defect-free surfaces could be prepared at low PES concentrations if the hollow fibers were spun at low temperatures by dry-jet wet spinning. A series of hollow fiber membranes were spun at different coagulation batch temperatures (<i>T</i><sub>c</sub>) and dope solution temperatures (<i>T</i><sub>d</sub>). Effects of <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub> on the membranes’ morphologies and gas separation performances were investigated. Membrane morphologies characterized by using a scanning electron microscope (SEM) showed that the skin layer thicknesses increased with the decreases in <i>T</i><sub>c</sub> and <i>T</i><sub>d</sub>. Moreover, mean surface pore sizes of the membranes, which were evaluated by using the gas permeation method, significantly decreased as <i>T</i><sub>c</sub> or <i>T</i><sub>d</sub> decreased. PES hollow fiber membranes spun at the lowest temperatures (<i>T</i><sub>c</sub> = 7 °C, <i>T</i><sub>d</sub> = 3 °C) showed O<sub>2</sub> and CO<sub>2</sub> permeances of 18.9 and 53.5 GPU, respectively. And selectivities of O<sub>2</sub>/N<sub>2</sub>, CO<sub>2</sub>/N<sub>2</sub>, and CO<sub>2</sub>/CH<sub>4</sub> gas pairs were 1.15, 3.26, and 1.24, respectively. After silicone coating, the selectivities increased to 7.24, 47.7, and 39.4, respectively, but O<sub>2</sub> and CO<sub>2</sub> permeances decreased to 4.85 and 31.9 GPU, respectively. To our best knowledge, the gas separation performance was the test among all PES hollow fiber membranes

    Molecular Design of Tröger’s Base-Based Polymers Containing Spirobichroman Structure for Gas Separation

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    Gas separation performance of glassy polymers can be improved by enhancing the polymer backbone stiffness to decrease the chain packing and increase the free volume and gas permeabilities. In this work, two Tröger’s base (TB)-based polymers were prepared by polymerization from two spirobichroman-containing diamine monomers, MSBC and SBC. The obtained TB-based polymers show good solubility in polar aprotic solvents including DMF, DMAc, NMP, and DMSO, high molecular weight, and high thermal stability. Gas separation performance of TB-MSBC and TB-SBC are much better than those of the 6FDA-MSBC and 6FDA-SBC, especially for H<sub>2</sub>/N<sub>2</sub> and H<sub>2</sub>/CH<sub>4</sub> gas pairs. Furthermore, the CO<sub>2</sub> permeability of TB-MSBC is about 7.6 times higher than that of 6FDA-MSBC. The much-improved separation performance of TB-based polymers can be mainly attributed to the ineffective chain packing via the incorporation of the spriobichroman structure and a ladder-type bridged bicyclic TB unit