Preparation and gas transport properties of dual‐layer polysulfone membranes for high pressure CO2 removal from natural gas

Permeability, sorption, and plasticization behaviors of dual‐layer composite membrane were studied. Polysulfone containing 10.7 wt % glycerol as additive was used for preparing a microporous membrane support. A thin top selective layer was prepared using diethylene glycol dimethyl ether as casting solvent. The overall performance of the membrane was evaluated using Scanning Electron Microscopy, and permeation and sorption tests at pressure up to 50 bar. The prepared membrane displayed high permeability at low pressure which gradually decreased with increase in pressure. Permeability of CO₂ was determined to be 84.97 Barrer at 2 bar. Membrane did not show any plasticization tendency up to the experimental pressure of 40 bar. Plasticization pressure and permeability at plasticization pressure were estimated to be 41.07 bar and 6.03 Barrer, respectively. The improved performance of the membrane is associated to the synergistic properties of the two layers prepared from different formulations of the same polymer. Thus, the dual‐layer flat sheet configuration displayed a potential in high pressure CO₂ removal from natural gas. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40924.     

Changes in free volume and gas permeation properties of poly(vinyl alcohol) nanocomposite membranes modified using cage-structured polyhedral oligomeric silsesquioxane

The present work reports the effect of various organically functionalized polyhedral oligomeric silsesquioxane (POSS) particles on the gas transport properties (N₂, O₂, and CO₂ molecules) in poly(vinyl alcohol) (PVA) membranes. The incorporation of polyethylene glycol-POSS (PEG-POSS), octa-tetramethylammonium-POSS (Octa-TMA-POSS) and m-POSS (Octa-TMA-POSS molecule was modified using cetyltrimethyl ammonium bromide) led to the enhancement in CO₂ separation performance of PVA, among which, PEG-POSS exhibited highest CO₂ separation due to the dipole-quadrupolar interaction of CO₂ with ethylene oxide group in POSS. Octa-TMA-POSS and m-POSS reduced the O₂ and N₂ permeability of the PVA membrane due to the reduction in the number of permeating pathways as compared to pure PVA. Free volume of the membranes was evaluated by positron annihilation lifetime spectroscopic (PALS) and coincidence Doppler broadening measurements. PALS confirms the increase in polymer free volume in PVA/POSS system due to the presence of rigid and spherical POSS molecule, which could enter in the polymer chain and provide viable pathway for molecular transport. Maxwel–Wagner–Sillar and Higuchi models were applied for the theoretical prediction of permeability of the fabricated membranes.     

Waterborne poly(urethane‐urea) gas permeation membranes for CO2/CH4 separation

In this work, dense membranes from aqueous dispersions of poly(urethane‐urea) (PUU) based on poly(propylene glycol) (PPG) and a block copolymer composed of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG), EG‐b‐PG, with 7 wt % of the former were obtained. Nonpolluting formulations were synthesized with proportions of PPG and EG‐b‐PG as 1:0, 1:1, 1:3, and 3:1 in terms of equivalent number ratios. The effect of small and gradual increases in PEG segments was evaluated for the permeability of pure CO₂, CH₄, and N₂, at room temperature. Slight increases in PEG‐based segments in PUU promoted some remarkable properties, which led to a simultaneous increase in CO₂ permeability and ideal selectivity for CH₄ (300%) and N₂ (380%). Infrared spectroscopy showed that the PEG portions induced hydrogen bonds between ? NH of urethane and ether groups in the PEG portions, which promoted ordering of the flexible segments, confirmed by X‐ray diffractometry and small‐angle X‐ray scattering. Diffractometry techniques also confirmed the absence of crystalline domains, as did dynamic mechanical analysis. The produced membranes showed performance above Robeson's 2008 upper bound and seemed to be a superior polymeric material for CO₂/CH₄ and CO₂/N₂ separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46003.     

Electrospun soy‐protein‐based nanofibrous membranes for effective antimicrobial air filtration

Soy proteins are gaining more and more attention because of its multifunction and biodegradability. Silver nanoparticles (AgNPs) are introduced into the nanofibers to prevent growth of microorganisms over the filter media. In the present study, the multifunctional and antimicrobial nanofibrous membranes were prepared by electrospinning the soy protein isolate (SPI)/polymide‐6 (PA6)‐silver nitrate system followed by ultraviolet reduction. The morphology of SPI/PA6 nanofibrous membranes was characterized by scanning electron microscopy. Antibacterial property of nanofibrous membranes were investigated against Escherichia coli and Bacillus subtilis. The optimized fiber membrane exhibited over 95% filtration efficiency of PM_0.3 (particulate matter size less than 0.3 μm). The successful synthesis of SPI/PA6‐AgNPs nanofibrous membranes would make it to be the potential candidate for novel antibacterial and high‐performance air filter. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45766.     

Crosslinking and stabilization of nanoparticle filled poly(1‐trimethylsilyl‐1‐propyne) nanocomposite membranes for gas separations

Poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) has been crosslinked using 4,4′‐diazidobenzophenone bisazide to improve its chemical and physical stability over time. Crosslinking PTMSP renders it insoluble in good solvents for the uncrosslinked polymer. Gas permeability and fractional free volume decreased as crosslinker content increased, while gas sorption was unaffected by crosslinking. Therefore, the reduction in permeability upon crosslinking PTMSP was due to decrease in diffusion coefficient. Compared with the pure PTMSP membrane, the permeability of the crosslinked membrane is initially reduced for all gases tested due to the crosslinking. By adding nanoparticles (fumed silica, titanium dioxide), the permeability is again increased; permeability reductions due to crosslinking could be offset by adding nanoparticles to the membranes. Increased selectivity is documented for the gas pairs O₂/N₂, H₂/N₂, CO₂/N₂, CO₂/CH and H₂/CH₄ using crosslinking and addition of nanoparticles. Crosslinking is successful in maintaining the permeability and selectivity of PTMSP membranes and PTMSP/filler nanocomposites over time. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Amphiphilic ABA‐type triblock copolymers for the development of high‐performance poly(vinylidene fluoride)/poly(vinyl pyrrolidone) blend ultrafiltration membranes for oil separation

ABA‐type amphiphilic triblock copolymers (TBCs) were synthesized by a reversible addition fragmentation chain transfer (RAFT) process with a telechelic polystyrene macro‐RAFT agent and 4‐[n‐(acryloyloxy)alkyloxy]benzoic acid monomers. Ultrafiltration (UF) membranes were fabricated by a phase‐inversion process with blends of the TBC, poly(vinylidene fluoride) (PVDF), and poly(vinyl pyrrolidone) (PVP) in dimethylformamide. The UF‐fabricated membranes were characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, thermogravimetric analysis, and differential scanning calorimetry. Pure water permeation, molecular weight cutoff values obtained by the permeation of different molecular weight polymers as probe solutes, bovine serum albumin (BSA) solution permeate flux, and oil–water emulsion filtration tests were used to evaluate the separation characteristics of the fabricated membranes. The tripolymer blend membranes exhibited a higher flux recovery ratio (FRR) after the membrane was washed with sodium lauryl sulfate (0.05 wt %) solution for a BSA solution (FRR = 88%) and oil–water emulsion (FRR = 95%) feeds when than the PVDF–PVP blend membrane (57 and 80% FRR values for the BSA solution and oil–water emulsion, respectively). The pendant carboxylic acid functional moieties in this ABA‐type TBC have potential advantages in the fabrication of high‐performance membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45132.     

Free volume defects and transport properties of mechanically stable polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol)‐poly(ethylene oxide) blend membranes

Polymer membrane based gas transport and pervaporation processes are fast growing areas in separation technology and have received wide attention as areas of ‘clean technology’. Mechanically stable novel polyhedral oligomeric silsesquioxane (POSS) embedded poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend membranes were prepared by solution blending followed by casting. The addition of carboxymethyl cellulose enhanced the interfacial activities of the PVA and PEO blends. The peripheral organic substituent on POSS plays a key role in achieving compatibility with polymers whereas the rigid Si–O–Si core of POSS imparts high mechanical strength. Compared to PVA membrane, poly(ethylene glycol) and octa(tetramethylammonium) functionalized POSS embedded PVA/PEO membranes exhibit 680% and 580% enhancement in Young's modulus as well as 130% and 140% improvement in tensile strength respectively. The Einstein, Kerner and Frankel–Acrivos models were applied to compare the experimental and theoretical Young's modulus of PVA‐PEO/POSS membranes. The presence of an ethylene oxide tail on POSS as well as PEO in the blend membrane enhances the CO₂ affinity of the membrane. The presence of a hydrophilic functional group on the POSS improves the hydrophilicity of the membrane and produces more binding sites for water molecules in the membrane during the pervaporation separation of a tetrahydrofuran–water azeotropic mixture. The transport properties of the membrane are further elucidated by means of free volume defect analysis carried out by positron annihilation lifetime spectroscopy and coincidence Doppler broadening spectroscopy. © 2019 Society of Chemical Industry     

Ultraviolet‐ray treatment of polysulfone membranes on the O2/N2 and CO2/CH4 separation performance

UV irradiation on polysulfone (PSF) membranes was studied to improve their gas‐separation properties. Membranes with 19–25% PSF contents were prepared by the phase‐inversion method, and the membrane surface was modified with UV rays with a wavelength of 312 nm and a power of 360 µw/cm². Measurements of gas permeation were conducted with pure carbon dioxide (CO₂), methane (CH₄), oxygen (O₂), and nitrogen (N₂) gases under 3–8 bar pressure at 25°C. Fourier transform infrared spectrometry revealed that the polar functional groups of hydroxyl and carbonyl were introduced by UV irradiation. The water contact angle of the treated membrane was reduced from 70–75° to 10–12° after 12 h of UV exposure. Scanning electron microscopy observation showed that the dense skin layer increased as the polymer concentration increased. After UV treatment, the permeation of O₂ decreased from 0.4–3.4 to 0.2–2.3 m³ m^?2 h^?1 bar^?1, whereas that of N₂, CO₂, and CH₄ increased for all of the pressures used from 0.1–1.7 m³ m^?2 h^?1 bar^?1 to about 0.1–3.4 m³ m^?2 h^?1 bar^?1; this depended on the applied pressure and the PSF content. As a result, the selectivity ratio of O₂/N₂ decreased from 1.9–7.8 to 0.6–1.5, whereas that of CO₂/CH₄ increased from 0.9–2.6 to 1.1–6.1. Moreover, the O₂/N₂ and CO₂/CH₄ of the untreated and the treated membranes decreased with increasing pressure and increased with increasing polymer concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42074.     

Properties of poly(ethylene terephthalate) containing epoxy‐functionalized polyhedral oligomeric silsesquioxane

Poly(ethylene terephthalate) (PET) containing epoxy‐functionalized polyhedral oligomeric silsesquioxane (POSS) was prepared by melt‐mixing and in situ polymerization methods. The melt‐mixed composite showed phase separation while the in situ polymerized composite did not, based on SEM characterization. During melt mixing, the reaction between the epoxy groups of POSS and hydroxyl groups of PET occurred, based on DSC results. DSC results on the in situ polymerization product showed formation of a lower‐melting component compared with PET. The tensile strength and modulus of the melt‐mixed composite fiber decreased compared with those properties of PET, whereas those of the in situ polymerized composite showed slightly higher values than PET despite the relatively small amounts (1 wt%) of POSS used. Dynamic mechanical analysis results showed an increase in storage modulus for the in situ polymerized composite of POSS and PET compared with PET over the temperature range of 40 °C to 140 °C. Copyright © 2004 Society of Chemical Industry     

Hyperbranched polyhedral oligomeric silsesquioxane (HB‐POSS) nanomaterials for high transmission and radiation‐resistant space and solar applications

Hyperbranched polycarbosiloxanes and polysiloxanes with octafunctional polyhedral oligomeric silsesquioxane (POSS) branchpoints and curable alkoxysilane or silanol end‐groups were formulated with linear polysiloxanes to fabricate transparent and robust nanostructured POSS‐containing materials for use in a range of high performance space and solar applications. The effect of methyl vs. phenyl content, architecture and linear polysiloxane mass on transmission, thermal, physical, and proton, electron and UV radiation resistance properties was determined, and the physical properties of the nanomaterials were tailored to produce adhesives, or rigid or flexible coatings as desired. The methyl formulations showed superior electron resistance relative to a commercial space control material and to a POSS‐free HB polymer control material, even when directly exposed to radiation in coating form, whereas the phenyl formulations were shown to have inferior electron and UV resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3849–3861, 2013     

Characterization of poly(vinyl pyrrolidone‐co‐isobutylstyryl polyhedral oligomeric silsesquioxane) nanocomposites

Poly(vinyl pyrrolidone‐co‐isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP–POSS) were synthesized by one‐step polymerization and characterized using FTIR, high‐resolution ¹H‐NMR, solid‐state ¹³C‐NMR, ²⁹Si‐NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The T_g of the PVP–POSS hybrid is influenced by three main factors: (1) a diluent role of the POSS in reducing the self‐association of the PVP; (2) a strong interaction between the POSS siloxane and the PVP carbonyl, and (3) physical aggregation of nanosized POSS. At a relatively low POSS content, the role as diluent dominates, resulting in a decrease in T_g. At a relatively high POSS content, the last two factors dominate and result in T_g increase of the PVP–POSS hybrid. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2208–2215, 2004     

Efficient cage structured polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol) membranes: Thermal degradation and mechanical stability in hydrated condition

In this work, the thermal degradation of functionalized cage structured polyhedral oligomeric silsesquioxane (POSS) incorporated poly(vinyl alcohol) (PVA) and poly(vinyl alcohol)-poly (ethylene oxide) (PEO) blend membranes were discussed. PVA-PEO/POSS and cross-linked PVA/POSS systems exhibited excellent improvement in thermal stability at lower loading of POSS as compared to pure PVA and uncross-linked PVA/POSS system. Uncross-linked PVA and PVA/POSS systems exhibited mainly two degradation steps. However, cross-linked PVA/POSS systems showed more degradation steps due to the formation of 3-dimentional network structure in the polymer. The mechanical stability of PVA/POSS and PVA-PEO/POSS systems at hydrated state were analyzed and observed a remarkable stability even in the wet condition.     

Properties of poly(butylene terephthalate) chain‐extended by epoxycyclohexyl polyhedral oligomeric silsesquioxane

Epoxycyclohexyl polyhedral oligomeric silsesquioxane (epoxy–POSS) was used to prepare a chain‐extended poly(butylene terephthalate) (PBT) with a twin‐screw extruder. The effect of epoxy–POSS on the melt flow index, mechanical properties, rheological behavior, and thermal properties of chain‐extended PBT was investigated. PBT had an intrinsic viscosity of 1.1 dL/g and a carboxy1 content of 21.6 equiv/10⁶ g, but the PBT chain‐extended with 2 wt % epoxy–POSS had an intrinsic viscosity of 1.7 dL/g and a carboxy1 content lower than 7 equiv/10⁶ g. After the addition of epoxy–POSS, the melt flow index of PBT dramatically decreased, the elongation at break increased greatly, the tensile strength increased slightly, and the thermal stability was also improved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fabrication of polysulfone nanocomposite membranes with silver‐doped carbon nanotubes and their antifouling performance

In this study, polysulfone (PSf)/silver‐doped carbon nanotube (Ag‐CNT) nanocomposite membranes were prepared by a phase‐inversion technique; they were characterized and evaluated for fouling‐resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet‐impregnation technique. The prepared Ag‐CNT nanotubes were characterized with scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat‐sheet PSf/Ag‐CNT nanocomposite membranes with different Ag‐CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (≥90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag‐CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag‐CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44688.     

Gas permeability of NH3‐plasma‐treated poly(methyl methacrylate) membranes

The effect of NH₃ plasma treatment on glassy poly(methyl methacrylate) (PMMA) membranes on the diffusion process for penetrant gases (CO₂, O₂, and N₂) was investigated from mean permeability data. The mean permeability coefficient for CO₂ definitely depended on the upstream pressure, whereas those for O₂ and N₂ remained constant regardless of the upstream pressure. For O₂ transport, the permeability increased a little with increasing treatment power, and for N₂ transport, it was not affected by the treatment power. For CO₂ transport, NH₃ plasma treatment promoted the transport of Langmuir mode, presumably through an increased Langmuir capacity constant for CO₂. NH₃ plasma treatment for PMMA membranes resulted in an increase in the separation factor of CO₂ relative to N₂ and in the permeability to CO₂. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1068–1072, 2003     

Tuning the gas separation performance of fluorinated and sulfonated PEEK membranes by incorporation of zeolite 4A

Mixed matrix membranes (MMMs) containing fluorinated‐sulfonated poly(ether ether ketone) (F‐SPEEK) and zeolite 4A filler, were prepared by solution casting. F‐SPEEK with a fixed degree of sulfonation (40%) was used for membrane synthesis. The SEM pictures showed good interfacial adhesion between filler particles and polymer, which was also confirmed by the increase in glass transition temperature of MMMs with increase in filler particles. Pure and mixed gas permeation experiments were carried out to investigate the potential of this membrane material. The results revealed that addition of zeolite 4A fillers enhanced both permeability and selectivity owing to the intrinsic nature of polymer and modified membrane morphology due to filler. The highest permeability obtained for CO₂ at 30% filler loading was 49.2 Barrer, while highest selectivities obtained for CO₂/CH₄ and CO₂/N₂ were 55 and 58 compared to 47 and 51 for the unfilled polymer, respectively. Intrinsic CO₂ solubility of F‐SPEEK was observed to be decreased from 10.7 to 1.9 (10^?2) cm³ (STP)/cm³ cmHg with the addition of Zeolite 4A. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45952.     

Preparation of poly(4‐methyl‐1‐pentene) asymmetric or microporous hollow‐fiber membranes by melt‐spun and cold‐stretch method

Poly(4‐methyl‐1‐pentene) (PMP) hollow fibers were prepared and fabricated into gas separation or microporous membranes by the melt‐spun and cold‐stretched method. PMP resin was melt‐extruded into hollow fibers with cold air as the cooling medium. The effects of take‐up speed and thermotreatment on the mechanical behavior and morphology of the fibers were investigated. Scanning electronic microscope (SEM) photos were used to reveal the geometric structure of the section and surface of the hollow fibers. It was found that the original fiber had an asymmetric structure. A “sandwich” mode was used to describe the formation of this special fine structure. And a series of PMP hollow‐fiber membranes were prepared by subsequent drawing, and it was found that there was a “skin–core” structure on the cross section of these hollow‐fiber membranes. Asymmetric or microporous PMP hollow‐fiber membranes could be obtained by controlling posttreatment conditions. The morphology of these membranes were characterized by SEM, and the gas (oxygen, nitrogen, and carbon dioxide) permeation properties of the membranes was measured. The results indicate that the annealing time of the original fiber and the stretching ratio were the key factors influencing the structure of the resulting membrane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2131–2141, 2006     

CO2‐facilitated transport through poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate)/polysulfone composite membranes

Poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate) (VSA–SA)/polysulfone (PS) composite membranes were prepared for the separation of CO₂. VSA–SA contained secondary amines and carboxylate ions that could act as carriers for CO₂. At 20°C and 1.06 atm of feed pressure, a VSA–SA/PS composite membrane displayed a pure CO₂ permeation rate of 6.12 × 10^?6 cm³(STP)/cm² s cmHg and a CO₂/CH₄ ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO₂ and 50 vol % CH₄, at 20°C and 1.04 atm of feed pressure, the CO₂ permeation rate was 9.2 × 10^?6 cm³ (STP)/cm² s cmHg, and the selectivity of CO₂/CH₄ was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO₂ over CH₄ and the CO₂ permeation rate had a maximum against the carrier concentration. The high CO₂ permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 275–282, 2006     

Thermal and mechanical properties of poly(ε‐caprolactone)/polyhedral oligomeric silsesquioxane nanocomposites

Poly(ε‐caprolactone) (PCL)/trisilanolphenyl polyhedral oligomeric silsesquioxane (TspPOSS) nanocomposites were prepared by solution mixing followed by film casting. Wide‐angle X‐ray diffraction and field‐emission scanning electron microscopy observations showed that the POSS molecules formed crystal domains and dispersed uniformly on the nanoscale in the PCL matrix. Fourier transform infrared analysis of the nanocomposites revealed that there are hydrogen‐bonded interactions between the silanol group of the TspPOSS and carbonyl oxygen of the PCL. Differential scanning calorimetry, tensile testing, and dynamic mechanical analysis (DMA) showed that, with increasing POSS content in the nanocomposites, the melting temperature and degree of crystallinity decreased while glass transition temperature, tensile modulus and strength increased without sacrificing the ductility of the PCL. DMA results also demonstrated the presence of a rubbery plateau above the melting temperature of the PCL/TspPOSS nanocomposites, and the moduli at the plateau region increased with increasing POSS content in the nanocomposites, implying that the PCL/TspPOSS nanocomposites formed a physically crosslinked structure. The physically crosslinked PCL/TspPOSS nanocomposites exhibited a thermally triggered shape memory effect. Copyright © 2012 Society of Chemical Industry     

Amine-impregnated natural zeolite as filler in mixed matrix membranes for CO2/CH4 separation

Flat mixed matrix membranes (MMMs) comprising polysulfone and clinoptilolite-type natural zeolite were prepared by casting. Zeolite was modified with three alkylamines: ethanolamine (EA), bis(2-hydroxypropyl)amine (BHPA), and polyethylenimine (PEI) by the impregnation method. Impregnated zeolite samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and N₂ adsorption–desorption. The alkylamine loading extent determined by thermogravimetric analysis was 5.2, 4.8, and 8.5% for EA, BHPA, and PEI, respectively. Analyses of MMMs showed that the incorporation of impregnated zeolite affected the glass-transition temperature (T_g) and mixed-gas transport properties. In this regard, a decreasing trend of the T_g values from 185.5 °C for the polymeric membrane up to 176.6 °C for Clino-EA-based MMM was recorded. In addition, the gas separation performance was evaluated at two different feed pressures. At 50 psi, MMMs showed an enhancement up to 30% on the CO₂ permeability (22.79 Barrer) and 55% on the CO₂/CH₄ selectivity (45.78) in comparison with the polymeric membrane (CO₂ permeability 17.34 Barrer; CO₂/CH₄ selectivity 29.38). These values varied depending on the alkylamine, BHPA being the most selective. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48286.