scholarly journals Development of CO2-Selective Polyimide-Based Gas Separation Membranes Using Crown Ether and Polydimethylsiloxane

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1927
Author(s):  
Dongyoung Kim ◽  
Iqubal Hossain ◽  
Asmaul Husna ◽  
Tae-Hyun Kim
Keyword(s):  
Crown Ether ◽  
Gas Separation ◽  
Structural Characteristics ◽  
Gel Permeation Chromatography ◽  
Diffusion Path ◽  
Gas Diffusion ◽  
Separation Performance ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Fine Grained

A series of CO2-selective polyimides (CE-PDMS-PI-x) was synthesized by copolymerizing crown ether diamine (trans-diamino-DB18C6) and PDMS-diamine with 4,4′-(hexafluoroisopropylidene) di-phthalic anhydride (6FDA) through the polycondensation reaction. The structural characteristics of the copolymers and corresponding membranes were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and gel permeation chromatography (GPC). The effect of PDMS loading on the CE-PDMS-PI-x copolymers was further analyzed and a very good structure–property relationship was found. A well-distributed soft PDMS unit played a key role in the membrane’s morphology, in which improved CO2-separation performance was observed at a low PDMS content (5 wt %). In contrast, the fine-grained phase separation adversely affected the separation behavior at a certain level of PDMS loading, and the PDMS was found to provide a flexible gas-diffusion path, affecting only the permeability without changing the selective gas-separation performance for the copolymers with a PDMS content of 20% or above.

scholarly journals The spirobichroman-based polyimides with different side groups: from structure–property relationships to chain packing and gas transport performance

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5086-5095
Author(s):  
Shuli Wang ◽  
Xiaohua Tong ◽  
Chunbo Wang ◽  
Xiaocui Han ◽  
Sizhuo Jin ◽  
...  
Keyword(s):  
Dihedral Angle ◽  
Gas Separation ◽  
Gas Transport ◽  
Critical Role ◽  
Polymer Membranes ◽  
Separation Performance ◽  
Structure Property ◽  
Chain Packing ◽  
Structure Property Relationships ◽  
Gas Separation Performance

Effect of substituents on the dihedral angle and chain packing plays a critical role in the enhancement in the gas separation performance of polymer membranes.

scholarly journals Poly(ether- block -amide) copolymer membrane for CO 2 /N 2 separation: the influence of the casting solution concentration on its morphology, thermal properties and gas separation performance

2019 ◽  
Vol 6 (9) ◽  
pp. 190866 ◽  
Author(s):  
Lidia Martínez-Izquierdo ◽  
Magdalena Malankowska ◽  
Javier Sánchez-Laínez ◽  
Carlos Téllez ◽  
Joaquín Coronas
Keyword(s):  
Gas Separation ◽  
Solution Concentration ◽  
Polymer Chains ◽  
Separation Performance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
Casting Solution ◽  
Feed Pressure ◽  
Gas Separation Performance

The present work is focused on the study of the effect that the casting solution concentration has on the morphology and gas separation performance of poly(ether- block -amide) copolymer membranes (Pebax ® MH 1657). With this aim, three different concentrations of Pebax ® MH 1657 in the casting solution (1, 3 and 5 wt%) were used to prepare dense membranes with a thickness of 40 µm. The morphology and thermal stability of all membranes were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, rotational viscometry and thermogravimetric analyses. An increase in crystallinity was notable when the amount of solvent in the Pebax ® MH 1657 solution was higher, mainly related to the polymer chains arrangement and the solvent evaporation time. Such characteristic seemed to play a key role in the thermal degradation of the membranes, confirming that the most crystalline materials tend to be thermally more stable than those with lower crystallinity. To study the influence of their morphology and operating temperature on the CO 2 separation, gas separation tests were conducted with the gas mixture CO 2 /N 2 . Results indicated that a compromise must be found between the amount of solvent used to prepare the membranes and the crystallinity, in order to reach the best gas separation performance. In this study, the best performance was achieved with the membrane prepared from a 3 wt% casting solution, reaching at 35°C and under a feed pressure of 3 bar, a CO 2 permeability of 110 Barrer and a CO 2 /N 2 selectivity of 36.

scholarly journals Pentiptycene-based ladder polymers with configurational free volume for enhanced gas separation performance and physical aging resistance

2021 ◽  
Vol 118 (37) ◽  
pp. e2022204118
Author(s):  
Tanner J. Corrado ◽  
Zihan Huang ◽  
Dezhao Huang ◽  
Noah Wamble ◽  
Tengfei Luo ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeation ◽  
Separation Performance ◽  
Structure Property ◽  
Mixed Gas ◽  
Initial Separation ◽  
Primary Advantage ◽  
Polymers Of Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) have shown promise in pushing the limits of gas separation membranes, recently redefining upper bounds for a variety of gas pair separations. However, many of these membranes still suffer from reductions in permeability over time, removing the primary advantage of this class of polymer. In this work, a series of pentiptycene-based PIMs incorporated into copolymers with PIM-1 are examined to identify fundamental structure–property relationships between the configuration of the pentiptycene backbone and its accompanying linear or branched substituent group. The incorporation of pentiptycene provides a route to instill a more permanent, configuration-based free volume, resistant to physical aging via traditional collapse of conformation-based free volume. PPIM-ip-C and PPIM-np-S, copolymers with C- and S-shape backbones and branched isopropoxy and linear n-propoxy substituent groups, respectively, each exhibited initial separation performance enhancements relative to PIM-1. Additionally, aging-enhanced gas permeabilities were observed, a stark departure from the typical permeability losses pure PIM-1 experiences with aging. Mixed-gas separation data showed enhanced CO2/CH4 selectivity relative to the pure-gas permeation results, with only ∼20% decreases in selectivity when moving from a CO2 partial pressure of ∼2.4 to ∼7.1 atm (atmospheric pressure) when utilizing a mixed-gas CO2/CH4 feed stream. These results highlight the potential of pentiptycene’s intrinsic, configurational free volume for simultaneously delivering size-sieving above the 2008 upper bound, along with exceptional resistance to physical aging that often plagues high free volume PIMs.

Synthesis and gas transport properties of sulfonated poly(ether ether sulfone) membranes containing pendant sulfonic acid groups

2020 ◽  
Vol 32 (8) ◽  
pp. 883-893
Author(s):  
Liexiang Ren
Keyword(s):  
Sulfonic Acid ◽  
Gas Permeability ◽  
Structural Characteristics ◽  
Gel Permeation Chromatography ◽  
Separation Performance ◽  
Visible Absorption ◽  
Separation Membranes ◽  
Different Temperatures ◽  
Sulfonic Acid Groups ◽  
Sulfonated Poly

A series of gas separation membranes based on sulfonated poly(ether ether sulfone)s (SPEESs) can be synthesized by the polycondensation and sulfonation reactions. The structural characteristics of copolymers were confirmed by 1H-NMR spectroscopy, Fourier-transform infrared spectroscopy, gel permeation chromatography, and ultraviolet–visible absorption spectroscopy. The permeability and selectivity behavior of these membranes were investigated using three single-gases (CO2, O2, and N2) at different temperatures of 25–55°C and pressures of 1.0–3.0 atm. The effect of sulfonation degree (SD), operating temperature, and pressure on gas permeability was explored and discussed. The results showed that SPEESs containing pendant sulfonic acid groups exhibited different separation performance. In particular, the SPEES-4 membrane with an SD of 67% exhibited the highest permeability (CO2 = 513.8 Barrer and O2 = 78.19 Barrer) at 55°C and 1 atm, whereas CO2/N2 and O2/N2 selectivity was 31.09 and 4.73, respectively.

scholarly journals Ultrapermeable Thin Film Composite Membranes Enhanced via Doping MOF Nanosheets

2020 ◽  
Author(s):  
Min Liu ◽  
Ke Xie ◽  
MITCHELL NOTHLING ◽  
Lianhai Zu ◽  
qiang fu ◽  
...  
Keyword(s):  
Thin Film ◽  
Gas Separation ◽  
Gas Permeability ◽  
Polymeric Materials ◽  
Composite Membranes ◽  
Gas Diffusion ◽  
Separation Performance ◽  
Film Composite ◽  
Thin Film Composite ◽  
Tfc Membrane

Thin film composite (TFC) membranes have attracted increasing interest to meet the demands of industrial gas separation. However, the development of high performance TFC membranes within their current configuration faces two key challenges: (i) the thickness-dependent gas permeability of polymeric materials (mainly polydimethylsiloxane (PDMS)) and (ii) the geometric restriction effect due to the limited pore accessibility of porous substrates. Here we demonstrate for the first time that the incorporation of trace (~1.8 wt%) amounts of amorphous metal-organic framework (aMOF) nanosheets into the gutter layer of TFC assemblies can simultaneously address these two limitations, with experimental evidence revealing the creation of rapid gas diffusion pathways along horizontal direction. Leveraging this strategy, we successfully fabricated a novel TFC membrane, consisting of a PDMS/aMOF gutter and an ultrathin (~54 nm) poly(ethylene glycol) top selective layer<i> via</i> surface-initiated atom transfer radical polymerization (ATRP). The complete TFC membrane exhibits excellent processability and the highest CO<sub>2</sub> permeance (1,990 GPU with a CO<sub>2</sub>/N<sub>2</sub> ideal selectivity of 39) yet observed for a TFC membrane employing a PDMS gutter layer. This study reveals an avenue for the design and fabrication of a new TFC membrane system with unprecedented gas separation performance.

scholarly journals The Phase Structural Evolution and Gas Separation Performances of Cellulose Acetate/Polyimide Composite Membrane from Polymer to Carbon Stage

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 618
Author(s):  
Haojie Li ◽  
Shan Xu ◽  
Bingyu Zhao ◽  
Yuxiu Yu ◽  
Yaodong Liu
Keyword(s):  
Heat Treatment ◽  
Cellulose Acetate ◽  
Gas Separation ◽  
Gas Permeability ◽  
Structural Evolution ◽  
Gas Diffusion ◽  
Separation Performance ◽  
Membrane Structures ◽  
Separation Performances

Blending and heat-treatment play significant roles in adjusting gas separation performances of membranes, especially for incorporating thermally labile polymers into carbon molecular sieve membranes (CMSMs). In this work, cellulose acetate (CA) is introduced into polyimide (PI) as a sacrificial phase to adjust the structure and gas separation performance from polymer to carbon. A novel result is observed that the gas permeability is reduced, even when the immiscible CA phase decomposes and forms pores after heat treatment at 350 °C. After carbonization at 600 °C, the miscible CA has changed without contribution, while the role of the immiscible CA phase has changed from original hindrance to facilitation, the composite-based CMSM at a CA content of 10 wt.% shows highest performances, a H2 permeability of ~5300 Barrer (56% enhancement) with a similar H2/N2 permselectivity of 42. The structural analyses reveal that the chain interactions and phase separation behaviors between CA and PI play critical roles on membrane structures and gas diffusion, and the corresponding phase structural evolutions during heat treatment and carbonization determine gas separation properties.

scholarly journals Ultrapermeable Thin Film Composite Membranes Enhanced via Doping MOF Nanosheets

2020 ◽  
Author(s):  
Min Liu ◽  
Ke Xie ◽  
MITCHELL NOTHLING ◽  
Lianhai Zu ◽  
qiang fu ◽  
...  
Keyword(s):  
Thin Film ◽  
Gas Separation ◽  
Gas Permeability ◽  
Polymeric Materials ◽  
Composite Membranes ◽  
Gas Diffusion ◽  
Separation Performance ◽  
Film Composite ◽  
Thin Film Composite ◽  
Tfc Membrane

Thin film composite (TFC) membranes have attracted increasing interest to meet the demands of industrial gas separation. However, the development of high performance TFC membranes within their current configuration faces two key challenges: (i) the thickness-dependent gas permeability of polymeric materials (mainly polydimethylsiloxane (PDMS)) and (ii) the geometric restriction effect due to the limited pore accessibility of porous substrates. Here we demonstrate for the first time that the incorporation of trace (~1.8 wt%) amounts of amorphous metal-organic framework (aMOF) nanosheets into the gutter layer of TFC assemblies can simultaneously address these two limitations, with experimental evidence revealing the creation of rapid gas diffusion pathways along horizontal direction. Leveraging this strategy, we successfully fabricated a novel TFC membrane, consisting of a PDMS/aMOF gutter and an ultrathin (~54 nm) poly(ethylene glycol) top selective layer<i> via</i> surface-initiated atom transfer radical polymerization (ATRP). The complete TFC membrane exhibits excellent processability and the highest CO<sub>2</sub> permeance (1,990 GPU with a CO<sub>2</sub>/N<sub>2</sub> ideal selectivity of 39) yet observed for a TFC membrane employing a PDMS gutter layer. This study reveals an avenue for the design and fabrication of a new TFC membrane system with unprecedented gas separation performance.

scholarly journals Multiple Amine-Contained POSS-Functionalized Organosilica Membranes for Gas Separation

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 194
Author(s):  
Xiuxiu Ren ◽  
Masakoto Kanezashi ◽  
Meng Guo ◽  
Rong Xu ◽  
Jing Zhong ◽  
...  
Keyword(s):  
Gas Separation ◽  
Mixed Matrix Membranes ◽  
Mixed Matrix Membrane ◽  
Separation Performance ◽  
Hybrid Membranes ◽  
Mixed Matrix ◽  
Translation Model ◽  
Good Thermal Stability ◽  
Oligomeric Silsesquioxane

A new polyhedral oligomeric silsesquioxane (POSS) designed with eight –(CH2)3–NH–(CH2)2–NH2 groups (PNEN) at its apexes was used as nanocomposite uploading into 1,2-bis(triethoxysilyl)ethane (BTESE)-derived organosilica to prepare mixed matrix membranes (MMMs) for gas separation. The mixtures of BTESE-PNEN were uniform with particle size of around 31 nm, which is larger than that of pure BTESE sols. The characterization of thermogravimetric (TG) and gas permeance indicates good thermal stability. A similar amine-contained material of 3-aminopropyltriethoxysilane (APTES) was doped into BTESE to prepare hybrid membranes through a copolymerized strategy as comparison. The pore size of the BTESE-PNEN membrane evaluated through a modified gas-translation model was larger than that of the BTESE-APTES hybrid membrane at the same concentration of additions, which resulted in different separation performance. The low values of Ep(CO2)-Ep(N2) and Ep(N2) for the BTESE-PNEN membrane at a low concentration of PNEN were close to those of copolymerized BTESE-APTES-related hybrid membranes, which illustrates a potential CO2 separation performance by using a mixed matrix membrane strategy with multiple amine POSS as particles.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

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