Effects of halloysite nanotubes on the morphology and CO2/CH4 separation performance of Pebax/polyetherimide thin-film composite membranes

Enhancing the performance of gas separation membranes is one of the major concerns of membrane researchers. Thus, in this study, poly(ether-block-amide) (Pebax)/polyetherimide (PEI) thin-film composite membranes were prepared and their CO₂/CH₄ gas separation performance was investigated by means of pure and mixed gases permeation tests. To improve the properties of these membranes, halloysite nanotubes (HNT) were added to Pebax layer at different loadings of 0.5, 1, 2, and 5 wt % to form Pebax-HNT/PEI membranes. Scanning electron microscopy, gas sorption, X-ray diffraction, Fourier-transform infrared, and differential scanning calorimetry tests were also performed to investigate the impact of HNT on structure and properties of prepared membranes. Results showed that both CO₂/CH₄ selectivity and CO₂ permeance increased by adding HNT to Pebax layer up to 2 wt %. By increasing HNT loading to 5 wt %, the CO₂/CH₄ selectivity decreased from 32 to 18, while CO₂ permeance increased from 3.25 to 4.2 GPU. Pebax/PEI and Pebax-HNT/PEI membranes containing 2 wt % of HNT were tested using CO₂/CH₄ gas mixtures at different feed CO₂ concentrations and feed pressure of 4 bar. The results showed that with increasing CO₂ concentration from 20 to 80 vol %, CO₂/CH₄ selectivity of Pebax/PEI composite membranes increased by 19%, while, in Pebax-HNT/PEI membrane, CO₂/CH₄ selectivity decreased by 40%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48860.     

Synthesis and characterization of poly(ether-<Emphasis Type="Italic">block</Emphasis>-amide) copolymers/multi-walled carbon nanotube nanocomposite membranes for CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation

One of the effective techniques for improving separation properties of polymeric membranes is incorporation of suitable nanoparticles into their matrices. This study presents the preparation of three types of nanocomposite membranes comprising three grades of poly (ether-block-amide) (Pebax 1074, Pebax 1657 and Pebax 2533) and modified multi-walled carbon nanotubes (MWCNTs) with different loadings (1, 1.5, 2 and 2.5 wt%). The prepared membranes were characterized by field emission scanning electron microscopy (FESEM), attenuated total reflection-Fourier transfer infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). Permeation of CO₂ and CH₄ gases through the prepared membranes was measured at the pressure range of 2-8 bars and 25 °C. The results showed that the incorporation of MWCNTs into the polymers matrices improves CO₂/CH₄ selectivity. Further, Pebax 1074/MWCNT nanocomposite membrane exhibits better performance for CO₂/CH₄ separation compared to the neat Pebax and the two other nanocomposite membranes.     

Effect of graphene oxide on the behavior of poly(amide‐6‐b‐ethylene oxide)/graphene oxide mixed‐matrix membranes in the permeation process

Polyether‐block‐amide (Pebax)/graphene oxide (GO) mixed‐matrix membranes (MMMs) were prepared with a solution casting method, and their gas‐separation performance and mechanical properties were investigated. Compared with the pristine Pebax membrane, the crystallinity of the Pebax/GO MMMs showed a little increase. The incorporation of GO induced an increase in the elastic modulus, whereas the strain at break and tensile strength decreased. The apparent activation energies (E_p) of CO₂, N₂, H₂, and CH₄ permeation through the Pebax/GO MMMs increased because of the greater difficulty of polymer chain rotation. The E_p value of CO₂ changed from 16.5 kJ/mol of the pristine Pebax to 23.7 kJ/mol of the Pebax/GO MMMs with 3.85 vol % GO. Because of the impermeable nature of GO, the gas permeabilities of the Pebax/GO MMMs decreased remarkably with increasing GO content, in particular for the larger gases. The CO₂ permeability of the Pebax/GO MMMs with 3.85 vol % GO decreased by about 70% of that of the pristine Pebax membrane. Rather than the Maxwell model, the permeation properties of the Pebax/GO MMMs could be described successfully with the Lape model, which considered the influence of the geometrical shape and arrangement pattern of GO on the gas transport. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42624.     

Effect of support layer on gas permeation properties of composite polymeric membranes

PES/Pebax and PEI/Pebax composite membranes were prepared by coating the porous PES and PEI substrate membranes with Pebax-1657. The morphology and performance of the prepared membranes were investigated by SEM and CO₂ and CH₄ permeation tests. The CO₂ permeances of 28 and 52 GPU were achieved for PES/Pebax and PEI/Pebax composite membranes, respectively, with CO₂/CH₄ selectivities almost equal to that of Pebax (26). The experimental data were further subjected to a theoretical analysis using the resistance model. It was found that the porosity and the thickness of the dense section of PES substrate were an order of magnitude higher than those of PEI substitute. The porosity/thickness ratio of PEI substrate was, however, higher than PES, explaining the higher permeance of PEI/Pebax composite membrane. Substrates with porosities much higher than the Henis-Tripodi gas separation membrane were used in this work, aiming to achieve the selectivity of Pebax, rather than those of the substrate membrane materials.     

Enhanced permeation performance of polyether-polyamide block copolymer membranes through incorporating ZIF-8 nanocrystals

Membrane-based CO2 separation is a promising alternative in terms of energy and environmental issues to other conventional techniques.Polyether-polyamide block copolymer (Pebax) membranes are promising for CO2 separation because of their excellent selectivity,but limited by their moderate gas permeability.In this study,fresh-prepared zeolitic imidazolate framework-8 (ZIF-8) nanocrystals were integrated into the Pebax(R)1657 matrices to form mixed matrix membranes.The resulting membrane exhibits significantly improved CO2 permeability (as high as 300％ increase),without the sacrifice of the selectivity,to the pristine polymer membrane.Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices.The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored.Mixed-gas permeation for both CO2/N2 and CO2/CH4 was also evaluated.The separation performance for CO2/CH4 mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound,and thus is technologically attractive for purification of natural gas.     

Carbon molecular sieve membranes derived from trimethylsilyl substituted poly(phenylene oxide) for gas separation

Carbon molecular sieve membranes for gas separation prepared using poly(phenylene oxide) (PPO) as precursor have been examined. The PPO precursor was modified by introducing a trimethylsilyl (TMS) substituent and its effect on the gas transport property of the resulting carbon membrane was examined. TMS-substituted PPO (TMSPPO) was prepared in a high yield by a simple one-step reaction, and its carbon membrane was successfully fabricated. The modification improved the gas permeability of the resulting membrane which also exhibited excellent O₂/N₂ and CO₂/CH₄ separation performance comparable to those of polyimide-derived carbon membranes. From the analysis of the microstructure of the TMSPPO carbon membranes, it is believed that the TMS groups improve gas diffusivity by increasing the micropore volume.     

Progress in Applications of Polymer-Based Membranes in Gas Separation Technology

Separation of gases through polymeric membrane by selective transport has immense advantages such as light weight, economical, high process flexibility, and space requirements. Fabrication methods of polymeric membrane (polysulfone, polyimide, polyamide, polycarbonate) and their properties along with fundamental principles for gas separation mechanism are discussed in this review. Polysulfone membranes are fabricated by dry/wet phase inversion process to investigate membrane properties. Polyimide membranes show great potential for gas separation and reveal good selectivity for CO₂/N₂ and CO₂/CH₄ gas pairs. Transport characteristics of polycarbonate membrane are improved by functionalization. Superior properties allow potential use of polymeric membranes in large-scale industrial applications.     

Mixed matrix membranes of Pebax1657 loaded with iron benzene‐1,3,5‐tricarboxylate for gas separation

Mixed matrix membranes offer major advantages in gas separation processes due to desirable properties found in both organic and inorganic membranes. In this study, a novel mixed matrix membrane was prepared for such application by incorporating iron benzene‐1,3,5‐tricarboxylate (Fe‐BTC) into the poly(amide‐6‐b‐ethylene oxide) (Pebax1657) polymer. Membranes with various loadings of 5, 10, and 20 wt% Fe‐BTC in the polymer matrix were fabricated to investigate the effect of filler loading on the membrane performance. Membranes, prepared by solution‐casting were characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, X‐ray diffraction, and tensile test. Pure gas separation of CO₂, CH₄, and N₂ and ideal gas selectivity of CO₂/CH₄ and CO₂/N₂ were performed and permeation tests were carried out under 4, 8, and 12 bar pressures. Results show that adding Fe‐BTC into the Pebax1657 matrix improved both permeability and selectivity of the filled membranes. For instance, 10 wt% loading of Fe‐BTC into the Pebax1657 matrix led to CO₂ permeability increase of 49% as well as CO₂/CH₄ and CO₂/N₂ selectivities enhancements of about 36% and 16%, respectively. POLYM. COMPOS., 38:1363–1370, 2017. © 2015 Society of Plastics Engineers     

Performance evaluation of a synthesized and characterized Pebax1657/PEG1000/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> membrane for CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation using response surface methodology

In this work, the response surface methodology (RSM) based on the central composite design (CCD) was used to examine effects of different gamma alumina (γ-Al₂O₃) loadings (0 to 8 wt.%) and various polyethylene glycol 1000 (PEG1000) contents (0 to 40 wt.%) as parameters on membrane preparation. Accordingly, pure carbon dioxide (CO₂) and methane (CH₄) gasses permeability and ideal CO₂/CH₄ selectivity values were considered as responses. Poly (ether block amide) 1657 (Pebax1657) was used as the base polymer matrix for the membranes fabrication. The neat Pebax1657 membrane was prepared via solution casting-solvent evaporation method and the other membranes were prepared via solution blending technique. Analysis of variance (ANOVA) was used to analyze the experiments statistically and the results indicated that the optimized amounts of γ-Al₂O₃ nanoparticles and PEG1000 in order to enhance both CO₂ permeability and ideal CO₂/CH₄ selectivity were 8 wt.% and 10 wt.%, respectively. Additionally, a comparison between the separation performance of the neat membrane, the nanocomposite membrane with the optimum amount of γ-Al₂O₃ nanoparticles, the blended membrane with optimum amounts of PEG1000, and the blended nanocomposite membrane with optimum amounts of γ-Al₂O₃ nanoparticles and PEG1000 was presented. The obtained gas permeation results showed that the blended nanocomposite membrane exhibits the highest CO₂/CH₄ separation performance compared to the neat Pebax membrane.     

Improved CO2/CH4 separation performance of mixed-matrix membrane by adding ZIF-7-NH2 nanocrystals

Membrane-based technology is an attractive alternative in terms of CO₂ separation. Pebax-based membranes are regarded as potential candidates for CO₂ separation due to the favorable interaction between its poly (ethylene oxide) chains with CO₂ molecules and inorganic fillers. However, the separation performance for CO₂/CH₄ mixture is still suffered from the moderate gas permeability and selectivity. To overcome this problem, in this work, amino-functionalized zeolite imidazolate framework (ZIF-7-NH₂) nanocrystals were used as fillers to blend with Pebax 1657 for fabricating mixed-matrix membranes (MMMs). XRD, Brunauer–Emmett–Teller (BET), scanning electron microscope, and ¹H nuclear magnetic resonance characterization indicated that ZIF-7-NH₂ with the highest crystallinity was synthesized. Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and Young's modulus showed that it has good interfacial interaction. Gas separation test results showed that both the CO₂ permeability and CO₂/CH₄ selectivity of the 31 wt% ZIF-7-NH₂/Pebax MMMs increased by 80 and 170%, respectively. The improved performance is attributed to the addition of ZIF-7-NH₂ nanocrystals and the favorable interfacial interactions between the polymer and ZIF-7-NH₂ nanocrystals. Furthermore, the polyvinylidene fluoride supported hollow fiber composite membranes also exhibit the long-term stability for CO₂/CH₄ separation.     

Methoxy poly (ethylene glycol) methacrylate-TiO2/poly (methyl methacrylate) nanocomposite: an efficient membrane for gas separation

Polymer/nanoparticle mixed matrix membranes (MMMs) is one of the most important topics in gas separation field. In this study, to improve gas separation efficiency, methoxy poly(ethylene glycol) methacrylate (MPEG) was grafted on TiO₂ surface and was used for synthesis of poly (methyl methacrylate) (PMMA) MMMs. Gas permeation and separation properties of PMMA/PMPEG-TiO₂ MMMs were studied for CO₂, CH₄, O₂, and N₂ gases. The results showed that the MMM filled with 5 wt% PMPEG-TiO₂ nanoparticle exhibited optimal separation performance with CO₂ permeability of 32.48 Barrer and CO₂/N₂ selectivity of 56.98, which are higher than pure polymer (2.75 Barrer and 36.71).     

Synthesis and Characterization of Ceramic Membranes (W‐Type Zeolite Membranes)

In this article, effects of synthesis parameters (synthesis temperature, synthesis time, and number of layers) on W‐type zeolite membranes synthesized over flat SUS supports for O₂/SF₆ gas separation were experimentally investigated. Experiments were carried out at these levels of synthesis temperature: 165°C, 185°C, and 200°C; synthesis time: 6, 12, and 18 h and number of layers: 1 and 2. Permeation measurements, XRD and SEM analysis were used for characterization of the synthesized membranes. The results showed that increasing synthesis temperature from 165°C up to 185°C increases separation factor of O₂/SF₆, however, further increasing decreases the separation performance. The same trend was observed for synthesis time for the single layer synthesized zeolite W membrane, although for the double layer synthesized zeolite W membrane, separation factor increased with increasing synthesis time. Repetition of layering has a net positive effect on separation factor of O₂/SF₆, and negative effect on permeation flux through the membranes. This behavior was attributed to the dual effect of synthesis temperature and synthesis time on selectivity. More zeolite crystals are deposited and larger crystals are formed at higher synthesis temperatures and longer synthesis times. Well W‐type zeolite membrane was synthesized at 185°C for 18 h with two repeating layers with a high separation factor of 20.1.     

ALTERNATIVE GENERATION OF H2, CO AND H2, CO2 MIXTURES FROM STEAM-CARBON DIOXIDE REFORMING OF METHANE AND THE WATER GAS SHIFT WITH PERMEABLE (MEMBRANE) REACTORS

A new process is proposed which converts CO₂ and CH₄ containing gas streams to synthesis gas, a mixture of CO and H₂ via the catalytic reaction scheme of steam-carbon dioxide reforming of methane or the respective one of only carbon dioxide reforming of methane, in permeable (membrane) reactors. The membrane reformer (permreactor) can be made by reactive or inert materials such as metal alloys, microporous ceramics, glasses and composites which all are hydrogen permselective. The rejected CO reacts with steam and converted catalytically to CO₂ and H₂ via the water gas shift in a consecutive permreactor made by similar to the reformer materials and alternatively by high glass transition temperature polymers. Both permreactors can recover H₂ in permeate by using metal membranes, and H₂ rich mixtures by using ceramic, glass and composite type permselective membranes. H₂ and CO₂ can be recovered simultaneously in water gas shift step after steam condensation by using organic polymer membranes. Product yields are increased through permreactor equilibrium shift and reaction separation process integration.

CO and H₂ can be combined in first step to be used for chemical synthesis or as fuel in power generation cycles. Mixtures of CO₂ and H₂ in second step can be used for synthesis as well (e.g., alternative methanol synthesis) and as direct feed in molten carbonate fuel cells. Pure H₂ from the above processes can be used also for synthesis or as fuel in power systems and fuel cells. The overall process can be considered environmentally benign because it offers an in-situ abatement of the greenhouse CO₂ and CH₄ gases and related hydrocarbon-CO₂ feedstocks (e.g., coal, landfill, natural, flue gases), through chemical reactions, to the upgraded calorific value synthesis gas and H₂, H₂ mixture products.     

Prediction of CO2/O2 absorption selectivity using supported ionic liquid membranes (SILMs) for gas–liquid membrane contactor

Given their unique and tunable properties as solvents, ionic liquids (ILs) have become a favorable solvent option in separation processes, particularly for capturing carbon dioxide (CO₂). In this work, a simple method that can be used to screen the suitable IL candidates was implemented in our modified gas–liquid membrane contactor system. Solubilities, selectivities of CO₂, nitrogen (N₂), and oxygen (O₂) gases in imidazolium-based ILs and its activity coefficients in water and monoethanolamine (MEA) were predicted using conductor-like screening model for real solvent (COSMO-RS) method over a wide range of temperature (298.15–348.15?K). Results from the analysis revealed that [emim] [NTf₂] IL is a good candidate for further absorption process attributed to its good hydrophobicity and CO₂/O₂ selectivity characteristics. While their miscibility with pure MEA was somehow higher, utilizing the aqueous phase of MEA would be beneficial in this stage. Data on absorption performances and selectivity of CO₂/O₂ are scarce especially in gas–liquid membrane contactor system. Therefore, considering [emim] [NTf₂] IL as a supporting material in supported ionic liquid membranes (SILMs), using aqueous phase of MEA as an absorbent would result in a great membrane-solvent combination system in furthering our gas–liquid membrane contactor process. In conclusion, COSMO-RS is a potentially great predictive utility to screen ILs for specified separation applications. In addition, this work provides useful results for the [emim] [NTf₂]-SILMs to be extensively applied in the field of CO₂ capture and selective O₂ removal.     

Preparation of ZIF-8—Pebax 1657 nanocomposite membranes for n-hexane/nitrogen separation as a representative of gasoline vapour recovery

Gasoline vapour emission is hazardous to both human health and the ecosystem and also results in capital loss, altogether revealing the necessity of its recovery. Some ZIF-8–Pebax flat nanocomposite membranes were fabricated by the method of solution casting and used for gasoline vapour recovery as represented by n-hexane vapour/nitrogen separation. Microporous ZIF-8 nanoparticles were synthesized and characterized by Fourier transform infrared (FTIR) and Brunauer–Emmett–Teller (BET) analysis. BET results revealed specific surface area, total volume, and average pore diameter of 940.8 m² · g⁻¹, 0.36 cm³ · g⁻¹, and 1.54 nm, respectively. Pure nitrogen and n-hexane vapour/nitrogen gas mixture permeabilities were measured through the membranes. There was a decline in both permeation rate and selectivity up to 5.0 wt.% of ZIF-8 loading and the next increment at their higher loadings to considerably more values that the pristine membrane. The maximum n-hexane vapour permeability and selectivity at 10.0 wt.% loading of ZIF-8 nanoparticles, the feed flow rate of 173 mL · min⁻¹, and permeate side pressure of −200 mbar were observed as 280.1 Barrer and 106.7, respectively, revealing 60.0% and 36.9% improvements compared with those of the pristine Pebax membrane. Observed 86%–92% n-hexane vapour recovery approves the successful application of the ZIF-8–Pebax nanocomposite membranes for n-hexane/nitrogen separation. The long-term separation performance of 5.0 wt.% ZIF-8 loaded nanocomposite membrane was improved by 76.5% compared with that of the pristine Pebax membrane.     

Rolltruded Poly(Aryl Ether Ether Ketone) (PEEK) for Membrane Applications

Abstract

An investigation of the transport and separation of several permanent gases (CO₂, N₂, CH₄, and H₂) and vapors (H₂O and ethanol) in unprocessed and rolltruded poly(aryl ether ether ketone) (PEEK) thin films has been conducted to evaluate PEEK for membrane applications requiring thermally and chemically stable materials. Transport coefficients and separation factors have been determined at permeation temperatures ranging from 40 to ca. 180°C. The gas transport coefficients were found to increase by up to 30% depending on the processing conditions. Actual separation factors, determined for a CO₂/N₂ gas mixture (24.6 vol% CO₂), were depressed slightly in comparison to the ideal values obtained from pure component data. In contrast, water and ethanol vapor permeabilities declined between 10 and 15% as a result of processing. For a 39.1 wt% vapor mixture of H₂O in EtOH, ideal and actual separation factors, determined at 130°C, were in good agreement. In contrast, order of magnitude improvements in the actual versus ideal separation factors were found for 11.7 and 7.6 wt% mixtures of H₂O in EtOH in both unprocessed and rolltruded PEEK. A comparison with other membranes considered for high temperature vapor dehydrations suggests that PEEK may be an excellent polymer for these applications.     

The effect of protic ionic liquids incorporation on CO2 separation performance of Pebax-based membranes

The separation of carbon dioxide (CO₂) is of great importance for environment protection and gas resource purification. The ionic liquids (ILs)-based gas separation membrane provides a new chance for efficient CO₂ separation, while high permeability and selectivity of membranes is a great challenge. In this study, the influence of two protic ILs with different anion ([TMGH][Im] and [TMGH][PhO]) on the CO₂ separation performance of the prepared ILs/Pebax blended membranes were systematically investigated at different temperature. The results showed the CO₂ permeability exhibits the rising trend for ILs/Pebax blended membranes with the increment of IL content. Especially, the [TMGH][Im] with low viscosity and high CO₂ absorption capacity leads to the blended membranes showing better CO₂ permeability and ideal CO₂ selectivity than that of membranes with [TMGH][PhO] at high IL content. Besides, with operating temperature increasing, the gas permeability of 20% (mass) [TMGH][Im]/Pebax blended membrane increases due to the decreasing viscosity of IL and the rising chain mobility of polymer. Inversely, the gas selectivity shows decreasing trend because CO₂ absorption capacity obviously decreased at higher temperature.     

Molecular design of nanohybrid gas separation membranes for optimal CO2 separation

Organic-inorganic materials comprising CO₂-philic components may yield superior CO₂ transport properties and good CO₂/H₂ gas selectivity. We report that a fine balance in size heterogeneity in the silicon-based structures is essential and a mixture of sizes up to 50 nm surrounded by 5–15 nm silicon-based nanostructures is the preferred inorganic phase morphology that yields optimal nanohybrid membranes. The combination of optimal synthesis conditions i.e. water/silicon ratio, condensation and ozone pre-treatment durations yields a nanohybrid membrane with a CO₂ permeability of 2000 Barrer while achieving a CO₂/H₂ selectivity of 11. The findings of this work are important for the design of gas separation membranes using green materials.     

Preparation of poly(ether‐block‐amide)/poly(amide‐co‐poly(propylene glycol)) random copolymer blend membranes for CO2/N2 separation

A series of poly(amide‐co‐poly(propylene glycol)) (PA‐PPG) random copolymers with different content of PPG were designed by polycondensation reaction. These random copolymers were blended up to 60% with commercially available Pebax 2533. The blend membranes were characterized by Fourier‐transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning electron microscope (SEM). Gas permeation properties of these blend membranes were investigated using five single‐gases (CO₂, H₂, O₂, CH₄, and N₂) at different temperature of 25–55°C and 1.0 atm. The impacts of content of PA‐PPG with different PPG content and operating temperature on CO₂ separation properties of Pebax/PA‐PPG blend membranes were studied. The results showed that CO₂ permeability gradually increased with the increasing operating temperature, whereas CO₂ permeability gradually decreased with the increase in content of PA‐PPG. CO₂/N₂ selectivity gradually increased with the increase in content of PA‐PPG. In particular, Pebax/PA‐PPG (50)–60% displayed excellent CO₂ and O₂ separation properties (P_CO2 = 79.7 Barrer and P_O2 = 13.6 Barrer, CO₂/N₂ = 34.7 and O₂/N₂ = 5.9) at 25°C and 1.0 atm. POLYM. ENG. SCI., 59:E14–E23, 2019. © 2018 Society of Plastics Engineers     

Blending PPO‐based molecules with Pebax MH 1657 in membranes for gas separation

This work explores the possibilities to blend block copolymers, i.e., Pebax MH 1657, with a variety of cheap poly(propylene oxide)‐rich molecules which could potentially play a double role in the resulting membranes as dispersing/stabilizing agents in multi‐component casting solutions and as a gas transport medium in the final membrane. These membranes were prepared by solution casting and were characterized by differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, X‐ray diffraction, density measurements, and Fourier transform infrared‐attenuated total reflection, while additive incorporation was also studied with theoretical calculations. Gas permeation measurements showed that this approach resulted in increased permeabilities at the expense of mixed‐gas selectivity. An interpretation of the blend structure was finally made using gas transport models. The compatibility of these additives with the synthesis of selective gas separation membranes may enable a potential double role in membrane synthesis, i.e., as stabilizing agents in membrane synthesis and as a gas transport medium in the final membrane. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46433.