scholarly journals Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1241 ◽  
Author(s):  
Silvio Neumann ◽  
Gisela Bengtson ◽  
David Meis ◽  
Volkan Filiz
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Time Lag ◽  
Polymer Chains ◽  
Separation Performance ◽  
Polymer Backbone ◽  
Cross Linkage ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

scholarly journals Boosting gas separation performance and suppressing the physical aging of polymers of intrinsic microporosity (PIM-1) by nanomaterial blending

Nanoscale ◽  
2020 ◽  
Vol 12 (46) ◽  
pp. 23333-23370 ◽  
Author(s):  
Mohd Zamidi Ahmad ◽  
Roberto Castro-Muñoz ◽  
Peter M. Budd
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Ideal Gas ◽  
Mixed Matrix Membranes ◽  
Separation Performance ◽  
Hybrid Fillers ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity ◽  
Gas Separation Performance ◽  
The Ideal

The development of PIM-1 mixed matrix membranes using organic, inorganic and hybrid fillers towards the ideal gas separation enhancement.

scholarly journals Effect of Bridgehead Methyl Substituents on the Gas Permeability of Tröger’s-Base Derived Polymers of Intrinsic Microporosity

Membranes ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 62 ◽  
Author(s):  
Richard Malpass-Evans ◽  
Ian Rose ◽  
Alessio Fuoco ◽  
Paola Bernardo ◽  
Gabriele Clarizia ◽  
...  
Keyword(s):  
Gas Permeability ◽  
Time Lag ◽  
Composite Membranes ◽  
Detailed Comparison ◽  
Gas Diffusion ◽  
Size Selectivity ◽  
Surface Areas ◽  
Troger's Base ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

A detailed comparison of the gas permeability of four Polymers of Intrinsic Microporosity containing Tröger’s base (TB-PIMs) is reported. In particular, we present the results of a systematic study of the differences between four related polymers, highlighting the importance of the role of methyl groups positioned at the bridgehead of ethanoanthracene (EA) and triptycene (Trip) components. The PIMs show BET surface areas between 845–1028 m2 g−1 and complete solubility in chloroform, which allowed for the casting of robust films that provided excellent permselectivities for O2/N2, CO2/N2, CO2/CH4 and H2/CH4 gas pairs so that some data surpass the 2008 Robeson upper bounds. Their interesting gas transport properties were mostly ascribed to a combination of high permeability and very strong size-selectivity of the polymers. Time lag measurements and determination of the gas diffusion coefficient of all polymers revealed that physical ageing strongly increased the size-selectivity, making them suitable for the preparation of thin film composite membranes.

scholarly journals Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

2021 ◽  
Author(s):  
Faiz Almansour ◽  
Monica Alberto ◽  
Rupesh S. Bhavsar ◽  
Xiaolei Fan ◽  
Peter M. Budd ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Separation Performance ◽  
Aging Effects ◽  
Methanol Vapor ◽  
Alcohol Vapor ◽  
Industrial Level ◽  
Vapor Treatment

AbstractPhysical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO2 and CH4 (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO2 permeability > 7000 barrer.

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.

scholarly journals Polymer of Intrinsic Microporosity (PIM-1) Membranes Treated with Supercritical CO2

Membranes ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 41 ◽  
Author(s):  
Colin Scholes ◽  
Shinji Kanehashi
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Supercritical Co2 ◽  
Physical Aging ◽  
Size Exclusion ◽  
Membrane Morphology ◽  
Polymers Of Intrinsic Microporosity ◽  
Micro Cavity ◽  
The Impact ◽  
Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) are a promising membrane material for gas separation, because of their high free volume and micro-cavity size distribution. This is countered by PIMs-based membranes being highly susceptible to physical aging, which dramatically reduces their permselectivity over extended periods of time. Supercritical carbon dioxide is known to plasticize and partially solubilise polymers, altering the underlying membrane morphology, and hence impacting the gas separation properties. This investigation reports on the change in PIM-1 membranes after being exposed to supercritical CO2 for two- and eight-hour intervals, followed by two depressurization protocols, a rapid depressurization and a slow depressurization. The exposure times enables the impact contact time with supercritical CO2 has on the membrane morphology to be investigated, as well as the subsequent depressurization event. The density of the post supercritical CO2 exposed membranes, irrespective of exposure time and depressurization, were greater than the untreated membrane. This indicated that supercritical CO2 had solubilised the polymer chain, enabling PIM-1 to rearrange and contract the free volume micro-cavities present. As a consequence, the permeabilities of He, CH4, O2 and CO2 were all reduced for the supercritical CO2-treated membranes compared to the original membrane, while N2 permeability remained unchanged. Importantly, the physical aging properties of the supercritical CO2-treated membranes altered, with only minor reductions in N2, CH4 and O2 permeabilities observed over extended periods of time. In contrast, He and CO2 permeabilities experienced similar physical aging in the supercritical treated membranes to that of the original membrane. This was interpreted as the supercritical CO2 treatment enabling micro-cavity contraction to favour the smaller CO2 molecule, due to size exclusion of the larger N2, CH4 and O2 molecules. Therefore, physical aging of the treated membranes only had minor impact on N2, CH4 and O2 permeability; while the smaller He and CO2 gases experience greater permeability loss. This result implies that supercritical CO2 exposure has potential to limit physical aging performance loss in PIM-1 based membranes for O2/N2 separation.

scholarly journals PEEK–WC-Based Mixed Matrix Membranes Containing Polyimine Cages for Gas Separation

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5557
Author(s):  
Marcello Monteleone ◽  
Riccardo Mobili ◽  
Chiara Milanese ◽  
Elisa Esposito ◽  
Alessio Fuoco ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Gas Separation ◽  
Gas Permeability ◽  
Time Lag ◽  
Mixed Matrix Membranes ◽  
Filler Materials ◽  
Separation Performance ◽  
Mixed Matrix ◽  
Neat Polymer ◽  
Matrix Membranes

Membrane-based processes are taking a more and more prominent position in the search for sustainable and energy-efficient gas separation applications. It is known that the separation performance of pure polymers may significantly be improved by the dispersion of suitable filler materials in the polymer matrix, to produce so-called mixed matrix membranes. In the present work, four different organic cages were dispersed in the poly(ether ether ketone) with cardo group, PEEK-WC. The m-xylyl imine and furanyl imine-based fillers yielded mechanically robust and selective films after silicone coating. Instead, poor dispersion of p-xylyl imine and diphenyl imine cages did not allow the formation of selective films. The H2, He, O2, N2, CH4, and CO2 pure gas permeability of the neat polymer and the MMMs were measured, and the effect of filler was compared with the maximum limits expected for infinitely permeable and impermeable fillers, according to the Maxwell model. Time lag measurements allowed the calculation of the diffusion coefficient and demonstrated that 20 wt % of furanyl imine cage strongly increased the diffusion coefficient of the bulkier gases and decreased the diffusion selectivity, whereas the m-xylyl imine cage slightly increased the diffusion coefficient and improved the size-selectivity. The performance and properties of the membranes were discussed in relation to their composition and morphology.

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