Recent Progress on Polymers of Intrinsic Microporosity and Thermally Modified Analogue Materials for Membrane‐Based Fluid Separations (original) (raw)
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European Polymer Journal, 2019
This review provides a new perception on the role of the state of-the-art polymers of intrinsic micro porosity (PIMs) in membrane-based gas separations performance including H 2 /CH 4, H 2 /N 2 , CO 2 /CH 4 , H 2 S/CH 4 , O 2 /N 2 , and C 2 H 4 /C 2 H 6 applications. Polymers of intrinsic micro porosity are novel amorphous microporous materials that have rigid backbone contorted macromolecular structure with high surface area and many other significant properties attracted the attention of researchers. In contrast to other types of porous organic polymers, PIMs are not included in the class of cross-linked covalent bonds thus they could be dissolved easily in organic solvents and transformed into robust films, fibers or coatings. Polymers of intrinsic micro porosity are considered as more effective among the inherently permeable membrane materials, alongwith their higher separation permeabilities and moderate selectivity that is the best fit into the Robeson upper bond model. This review brings a general overview of the preparation, separation mechanism and gas separation performances of novel polymers of intrinsic micro porosity materials that have been made in the last 16 yr along with their permeability and selectivity on the pure-gas upper bounds.
Macromolecules, 2012
Cross-linked membranes for gas separation have been prepared by thermal treatment of carboxylated polymers of intrinsic microporosity (C-PIMs). The optimal cross-linking temperature was investigated and possible cross-linking pathways involving aryl radical-induced thermal decarboxylation are provided, while several other possible mechanisms are ruled out. Carboxylated PIMs are accessible by controlled hydrolysis of the nitrile-containing parent polymer. The resulting cross-linked PIMs were insoluble in typical solvents and were characterized by Fourier transform infrared spectroscopy (FTIR), TGA-MS, TGA-FTIR, and gel content analysis. The decarboxylated PIM (DC-PIM) membranes showed higher selectivities for the O 2 /N 2 ,CO 2 /N 2 , and CO 2 /CH 4 gas pairs, with evidence of suppression of swelling-induced densification under high CO 2 pressure.
2021
Trade-off between permeability and nanometer-level selectivity is an inherent shortcoming of membrane-based separation of molecules, while most highly porous materials with high adsorption capacity lack solution processability and stability for achieving adsorption-based molecule separation. We hereby report a hydrophilic amidoxime modified polymer of intrinsic microporosity (AOPIM-1) as a membrane adsorption material to selectively adsorb and separate small organic molecules from water with ultrahigh processing capacity. The membrane adsorption capacity for Rhodamine B reaches 26.114 g m−2, 10~1000 times higher than previously reported adsorptive membranes. Meanwhile, the membrane achieves >99.9% removal of various nano-sized organic molecules with water flux 2 orders of magnitude higher than typical pressure-driven membranes of similar rejections. This work confirms the feasibility of microporous polymers for membrane adsorption with unprecedented capacity, and provides the pos...
ACS Applied Polymer Materials, 2021
investigated under different solvent (dimethylformamide (DMF) and dimethylacetamide/dichlorobenzene) and temperature (65−160°C) conditions to produce a range of topologically different polymer samples. Characterization of the polymers, particularly with proton NMR spectroscopy and multiple detector SEC analysis, indicated that, like PIM-1, the polymerizations proceeded with a degree of polymer chain branching. This is attributed to the occurrence of monosubstitution reactions, instead of disubstitution, which eventually leads to a significant proportion of colloidal network formation. However, all polymer samples remained soluble/ dispersible in chloroform at the concentration required to cast self-standing films. This work reports the first examination of PIM-Py as a membrane for gas separation applications. The most structurally diverse PIM-Py samples produced films that exhibited selectivity/permeability balances in single gas permeation studies above the 2008 Robeson upper bound for the CO 2 /N 2 gas pair. Indeed, a film cast from the highest colloidal network content sample surpassed the recently introduced 2019 CO 2 /N 2 upper bound. After 143 days of aging, a 40 μm self-standing membrane still exhibited a single gas CO 2 permeability of 4480 barrer and an ideal CO 2 /N 2 selectivity of 45. The polymers produced in lower temperature reactions in DMF exhibited gas separation performances very similar to a structurally regular "normal" PIM-1 polymer, sitting on or around the 2008 Robeson upper bound line. Single gas permeation measurements to determine CO 2 /CH 4 selectivity showed similar trends across the range of polymer samples, without generally reaching high selectivities as for the CO 2 /N 2 pair. Mixed gas CO 2 /CH 4 permeation measurements with aging were also completed for PIM-Py membranes, which indicated similar gas separation performance to a structurally regular PIM-1 polymer. This study would suggest that, like PIM-1, gas separation performance of PIM-Py is greatly influenced by the topological balance toward branched and network material within the polymer sample.
Gas-Separation Membranes Loaded with Porous Aromatic Frameworks that Improve with Age
Angewandte Chemie (International ed. in English), 2015
Porosity loss, also known as physical aging, in glassy polymers hampers their long term use in gas separations. Unprecedented interactions of porous aromatic frameworks (PAFs) with these polymers offer the potential to control and exploit physical aging for drastically enhanced separation efficiency. PAF-1 is used in the archetypal polymer of intrinsic microporosity (PIM), PIM-1, to achieve three significant outcomes. 1) hydrogen permeability is drastically enhanced by 375 % to 5500 Barrer. 2) Physical aging is controlled causing the selectivity for H2 over N2 to increase from 4.5 to 13 over 400 days of aging. 3) The improvement with age of the membrane is exploited to recover up to 98 % of H2 from gas mixtures with N2 . This process is critical for the use of ammonia as a H2 storage medium. The tethering of polymer side chains within PAF-1 pores is responsible for maintaining H2 transport pathways, whilst the larger N2 pathways gradually collapse.