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Scheme 1. Synthesis of aromatic, fluorinated dianhydride, 4,4 -(hexafluoroisopropylidene)-diphthalic anhydride (6FDA)-based imide monomers. a: DMF (5 • C, 1 h; RT, 24 h); b: Toluene (125 • C, 24 h); c: Ac 2 O (70 • C, 16 h).
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![Figure 1. [Rmim][Tf2N] ionic liquids (ILs) utilized to form...](publication/334211612/figure/fig3/AS:776767019184133@1562207097579/RmimTf2N-ionic-liquids-ILs-utilized-to-form-polyimide-ionene-IL-composites_Q320.jpg)
Three new isomeric 6FDA-based polyimide-ionenes, with imidazolium moieties and varying regiochemistry (para-, meta-, and ortho- connectivity), and composites with three different ionic liquids (ILs) have been developed as gas separation membranes. The structural-property relationships and gas separation behaviors of the newly developed 6FDA polyimi...
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Context 1
... and 3-butyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl) sulfonyl)amide ([Bnmim] [Tf2N]) followed procedures previously introduced in the literature [24]. The ionic liquids shown in Figure 1 were incorporated as discussed in the following section on membrane formation. ...Context 2
... and 3-butyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl) sulfonyl)amide ( [Bnmim][Tf 2 N]) followed procedures previously introduced in the literature [24]. The ionic liquids shown in Figure 1 were incorporated as discussed in the following section on membrane formation. ...Context 3
... H-NMR and 13 C-NMR were utilized for structural confirmation of the monomers and polyimide-ionenes. NMR chemical shifts [δ] are reported in the experimental section, with spectra included in Figures S1-S6. 1 H-NMR of the monomers supports formation of bis-imidazole imide monomers, indicated by the disappearance of the broad NH 2 peak and a downfield shift of all peaks in the aromatic region as a result of imidization. Additionally, the chemical shifts between 9.59-10.04 ...Context 4
... scanning calorimetry (DSC) was utilized to determine T g values for the three PI-ionenes and aforementioned IL hybrids. The thermal data are summarized in Table 2, with plots included in a supporting document (See Figure S8-S21). The d-spacing values for all derivatives are also summarized in Table 2, and discussed later in Section 3.3. ...Citations
... Then the researchers discovered that the membrane of composite form with functionalization of polymeric materials may fulfill the aforementioned criteria Alqaheem et al. 2017;Maheswari and Palanivelu 2017;Bei et al. 2021). Over the decades, a lot of polymeric composite membranes have been produced with different polymeric materials (cellulose acetate (CA) and its derivatives (Shieh and Chung 2000;Mao et al. 2011;Ahmad et al. 2014;Shankar and Kandasamy 2019), polysulfones (PSf) (Scholes et al. 2010a;Rafiq et al. 2012), polycarbonates (PC) (Hellums et al. 1989;Iqbal et al. 2008), polyethylene oxides (PEO) (Suzuki et al. 1998;Wang et al. 2014;Lee and Kang 2019), perfluoropolymers (PFP) (Jansen et al. 2006;Scholes et al. 2015;Fang et al. 2016), natural or synthetic rubbers (Zhuang et al. 2018;Tseng et al. 2019), polypropylene (PP) (Teramae and Kumazawa 2007;, polyamines (PA) (Matsuyama et al. 1996;Kim et al. 2004;Shen et al. 2015;Chen et al. 2016), polyimides (PI) (Marek et al. 1996;Hillock and Koros 2007;Harra et al. 2019), co-polymers (Sridhar et al. 2007c;Ji et al. 2009;Chen et al. 2015), etc.) by various researchers' extensively in CO 2 gas separation application and they are observed remarkable results in lab scale and industrial scale (Alqaheem et al. 2017;Brinkmann et al. 2017). ...
Carbon dioxide (CO2) emission to the atmosphere is the prime cause of certain environmental issues like global warming and climate change, in the present day scenario. Capturing CO2 from various stationary industrial emission sources is one of the initial steps to control the aforementioned problems. For this concern, a variety of resources, such as liquid absorbents, solid adsorbents, and membranes, have been utilized for CO2 capturing from various emission sources. Focused on membrane-based CO2 capture, polymeric membranes with composite structure (polymeric composite membrane) offer a better performance in CO2 capturing process than other membranes, due to the composite structure it offers higher gas flux and less material usage, thus facile to use high performed expensive material for membrane fabrication and achieved good efficacy in CO2 capture. This compressive review delivers the utilization of different polymeric composite membranes in CO2 capturing applications. Further, the types of polymeric materials used and the different physicochemical modifications of those membrane materials and their CO2 capturing ability are briefly discussed in the text. In conclusion, the current status and possible perspective ways to improve the CO2 capture process in industrial CO2 gas separation applications are described in this review.
... Though polyimides possess many attractive features, most of the wholly aromatic polyimides with rigid structures for thermo-dimensional stability generally suffer poor solubility in organic solvents, which often frustrates their diverse application [2]. To overcome this problem, various structural modifications of polyimides have been attempted over the last few decades [3][4][5][6][7][8]. ...
A series of soluble aromatic poly(amide-imide)s (PAIs) was prepared from a new diamide–diamine monomer having biphenyl units with two CF3 groups. The diamide–diamine monomer was polymerized with 2,2′-bis(trifluoromethyl)benzidine and pyromelltic dianhydride through an imidization reaction to prepare PAIs with a controlled imide/amide bond ratio in the main chains. While the PAIs with the highest imide bond content showed a limited solubility, other PAIs were soluble in polar organic solvents and can be solution-cast into flexible freestanding films. All PAIs exhibited high thermal stability with 5% weight loss temperature (Td5) from 464 to 497 °C in air, and no appearance of glass transition up to 400 °C. Notably, the linear coefficient of thermal expansion (CTE) value of the PAI films was linearly decreased with the imide bond content and varied from 44.8 to 7.8 ppm/°C.
... PILs and ionenes are generally very similar and share the same field of applications [68]. However, while PILs are often based on mono-functional alkenyl moieties, and therefore, possess an aliphatic, non-ionic backbone, literature reports on ionenes increasingly focus on the introduction of ionic groups in high performance polymers such as polyimides [63,69] or aromatic polyamides [64,70]. Furthermore, the position of the ions influences the ion aggregation [71] and an increased ion conductivity was found for ionenes in comparison to a polyelectrolyte [72]. ...
Poly(ionic liquids) (PILs) and ionenes are polymers containing ionic groups in their repeating units. The unique properties of these polymers render them as interesting candidates for a variety of applications, such as gas separation membranes and polyelectrolytes. Due to the vast number of possible structures, numerous synthesis protocols to produce monomers with different functional groups for task-specific PILs are reported in literature. A difunctional epoxy-IL resin was synthesized and cured with multifunctional amine and anhydride hardeners and the thermal and thermomechanical properties of the networks were assessed via differential scanning calorimetry and dynamic mechanical analysis. By the selection of suitable hardeners, the glass transition onset temperature (Tg,onset) of the resulting networks was varied between 18 °C and 99 °C. Copolymerization of epoxy-IL with diglycidyl ether of bisphenol A (DGEBA) led to a further increase of the Tg,onset. The results demonstrate the potential of epoxy chemistry for tailorable PIL networks, where the hardener takes the place of the ligands without requiring an additional synthesis step and can be chosen from a broad range of commercially available compounds.
... Many factors such as molecular packing, molecular ordering, free volume, and internal motions around bonds in molecules affect the polymer properties and depend mainly on the polymer structure and preparation conditions. There is a strong relationship between the properties and structure of the polymers that have to be fully understood to be able to design suitable polymers for a targeted application [311]. Small changes in the morphology and chemical structure can have a profound impact on the gas separation performance. ...
In the last decades, many novel polymeric materials have been considered to prepare highly energy-efficient gas separation membranes. There is a continuous search to overcome the trade-off relationship between the gas permeability and selectivity to improve the membrane separation performance during long-term operation. One of the most important research fields of molecular design and polymer chemistry is the synthesis of new polymers with a highly microporous structure, referred to as polymers of intrinsic microporosity (PIMs) and thermally rearranged (TR) polymers. The major challenge of PIMs and TR polymers, required for their application in membrane gas separation, is achieving a high permeability and selectivity, which remain stable over prolonged periods and under all possible operating conditions. Limits of their use can be low mechanical stability, sophisticated and challanging synthesis methods, physical aging of PIMs, etc. For TR polymers, identifying the optimum temperature in the thermal treatment process is challenging, and the preparation of thin-film TR membranes from PBO precursor via conventional methods is difficult. Moreover, the productivity of the membrane modules and the adhesion between the support/polymer and nanomaterials/polymer need to be improved in mixed matrix membranes (MMMs). Also, the formation of defects in the membrane structure is the main challenge to overcome for the fabrication of thin-film composites (TFCs).
In this manuscript, we carefully review the molecular design and the properties and performance of PIMs and TR materials as energy-efficient membranes for various gas separations, emphasizing CO2/CH4 and CO2/N2. Different methods for synthesizing PIMs and TR polymers are described, and the resulting polymers are evaluated for gas separation. Structure designing for the synthesis of PIMs and TR membranes and the influence of different chemical structures of monomers for creating chain rigidity by non-planar groups, and tuning the angle of contorted centres, are investigated. Moreover, the presence of functional groups and other substituents, such as fluorinated, sulfonated, carboxylic, tetrazole, and other groups, are investigated. Different strategies for membrane preparation and tailoring of their properties, such as cross-linking, co-polymerization, blending with other polymeric or organic and inorganic materials, are discussed as well.
... The gas transport behaviors of these PIL: free IL or crosslinking IL composite films were investigated using a high-vacuum time-lag apparatus in our laboratories, based on the constant-volume/variable-pressure method, which have been detailed in our previous works [25,26,28,39,40]. To avoid membrane fracture due to edge pressure from the O-ring within the unit, the membranes were masked using an adhesive aluminum tape in order to confine gas permeation through a fixed membrane area of ½" diameter (A = 0.196 in 2 ). ...
... The gas transport behaviors of these PIL: free IL or crosslinking IL composite films were investigated using a high-vacuum time-lag apparatus in our laboratories, based on the constant-volume/variable-pressure method, which have been detailed in our previous works [25,26,28,39,40]. To avoid membrane fracture due to edge pressure from the O-ring within the unit, the membranes were masked using an adhesive aluminum tape in order to confine gas permeation through a fixed membrane area of 1 2 " diameter (A = 0.196 in 2 ). ...
... Robeson plots depicting the CO2 selectivity against N2, CH4, and H2 for the PIL:IL-filled membranes in this work for comparison with relevant membrane materials[4,26,28,37,[39][40][41][43][44][45]. (a) αCO2/CH4 vs. PCO2; (b) αCO2/N2 vs. PCO2; (c) αCO2/H2 vs. PCO2. ...
This work introduces a series of vinyl-imidazolium-based polyelectrolyte composites, which were structurally modified via impregnation with multivalent imidazolium-benzene ionic liquids (ILs) or crosslinked with novel cationic crosslinkers which possess internal imidazolium cations and vinylimidazolium cations at the periphery. A set of eight [C4vim][Tf2N]-based membranes were prepared via UV-initiated free radical polymerization, including four composites containing di-, tri-, tetra-, and hexa-imidazolium benzene ILs and four crosslinked derivatives which utilized tri- and tetra- vinylimidazolium benzene crosslinking agents. Structural and functional characterizations were performed, and pure gas permeation data were collected to better understand the effects of "free" ILs dispersed in the polymeric matrix versus integrated ionic crosslinks on the transport behaviors of these thin films. These imidazolium PIL:IL composites exhibited moderately high CO2 permeabilities (~20-40 Barrer), a 4-7× increase relative to corresponding neat PIL, with excellent selectivities against N2 or CH4. The addition of imidazolium-benzene fillers with increased imidazolium content were shown to correspondingly enhance CO2 solubility (di- < tri- < tetra- < hexa-), with the [C4vim][Tf2N]: [Hexa(Im+)Benz ][Tf2N] composite showing the highest CO2 permeability (PCO2 = 38.4 Barrer), while maintaining modest selectivities (αCO2/CH4 = 20.2, αCO2/N2 = 23.6). Additionally, these metrics were similarly improved with the integration of more ionic content bonded to the polymeric matrix; increased PCO2 with increased wt% of the tri- and tetra-vinylimidazolium benzene crosslinking agent was observed. This study demonstrates the intriguing interactions and effects of ionic additives or crosslinkers within a PIL matrix, revealing the potential for the tuning of the properties and transport behaviors of ionic polymers using ionic liquid-inspired small molecules.
... Elrasheedy et al. [186] reviewed water applications of membranes. Also, O'Harra et al. [187] fabricated composite membranes for gas separation. Supercapacitor electrodes are produced from carbon nanotube and cellulose combinations. ...
In this paper, a review of the compatibility of polymeric membranes with lignocellulosic biomass is presented. The structure and composition of lignocellulosic biomass which could enhance membrane fabrications are considered. However, strong cell walls and interchain hindrances have limited the commercial-scale applications of raw lignocellulosic biomasses. These shortcomings can be surpassed to improve lignocellulosic biomass applications by using the proposed pretreatment methods, including physical and chemical methods, before incorporation into a single-polymer or copolymer matrix. It is imperative to understand the characteristics of lignocellulosic biomass and polymeric membranes, as well as to investigate membrane materials and how the separation performance of polymeric membranes containing lignocellulosic biomass can be influenced. Hence, lignocellulosic biomass and polymer modification and interfacial morphology improvement become necessary in producing mixed matrix membranes (MMMs). In general, the present study has shown that future membrane generations could attain high performance, e.g., CO2 separation using MMMs containing pretreated lignocellulosic biomasses with reachable hydroxyl group radicals.
... The resulting macromolecular species is called polyimidic ionenes or imidic poly(ionic liquid)s. The strategy uses ionic liquids' strong affinity to CO2 with the high-performance characteristics of PIs for the development of new materials for gas membrane separation [110][111][112][113]. ...
The development of high-performance bio-based polyimides (PIs) seems a difficult task due to the incompatibility between petrochemical-derived, aromatic monomers and renewable, natural resources. Moreover, their production usually implies less eco-friendly experimental conditions, especially in terms of solvents and thermal conditions. In this chapter, we touch some of the most significant research endeavors that were devoted in the last decade to engineering naturally derived PI building blocks based on nontoxic, bio-renewable feedstocks. In most cases, the structural motifs of natural products are modified toward amine functionalities that are then used in classical or nonconventional methods for PI synthesis. We follow their evolution as viable alternatives to traditional starting compounds and prove they are able to generate eco-friendly PI materials that retain a combination of high-performance characteristics, or even bring some novel, enhanced features to the field. At the same time, serious progress has been made in the field of nonconventional synthetic and processing options for the development of PI-based materials. Greener experimental conditions such as ionic liquids, supercritical fluids, microwaves, and geothermal techniques represent feasible routes and reduce the negative environmental footprint of PIs’ development. We also approach some insights regarding the sustainability, degradation, and recycling of PI-based materials.
... Our recent review highlights the progress of ionenes and their convergence with high-performance applications [7]. The utility of ionenes has been demonstrated in separations and CO2 capture [8][9][10][11][12][13], ionexchange or conducting membranes [14], antimicrobial coatings [15][16][17][18], batteries [19][20][21], electrochromic devices [22], hydrogels and gelators [23][24][25], water treatment [26], and fiber applications [12,27,28]. Nearly all known ionenes bear cationic moieties such as ammonium, phosphonium, pyrrolidinium, pyridinium, triazolium, and imidazolium groups [8,14,20,22,23,[29][30][31][32][33][34]. ...
... Long's group has emphasized the progress and versatile applicability of ammonium, imidazolium, and phosphonium ionenes [32,38,39]. Previous literature by Bara and coworkers has demonstrated the expansive possibilities of imidazolium ionenes, shifting toward more "high-performance" materials and exploring the effects of introducing imidazolium ILs into the ionene matrix [9,10,13,28,36,40,41]. We have demonstrated the suitability of imidazolium ionenes applied as CO2-selective gas separation membranes, self-healing and shape memory materials, 3D printing feedstocks, and as fibers [9][10][11][12][13]27,28]. The tailorability of this imidazolium platform is vast, when creative chemistries are employed to probe the effects of structural or connective variation of the cyclic cation, substitution, charge density, functionality, and modification of properties via addition of ILs. ...
... Previous literature by Bara and coworkers has demonstrated the expansive possibilities of imidazolium ionenes, shifting toward more "high-performance" materials and exploring the effects of introducing imidazolium ILs into the ionene matrix [9,10,13,28,36,40,41]. We have demonstrated the suitability of imidazolium ionenes applied as CO2-selective gas separation membranes, self-healing and shape memory materials, 3D printing feedstocks, and as fibers [9][10][11][12][13]27,28]. The tailorability of this imidazolium platform is vast, when creative chemistries are employed to probe the effects of structural or connective variation of the cyclic cation, substitution, charge density, functionality, and modification of properties via addition of ILs. ...
Here we introduce the synthesis and thermal properties of a series of sophisticated imidazolium ionenes with alternating amide-amide or amide-imide backbone functionality, and investigate the structural effects of mono(imidazolium) and unprecedented tris(imidazolium) ionic liquids (ILs) in these ionenes. The new set of poly(amide-amide) (PAA) and poly(amide-imide) (PAI) ionenes represent the intersection of conventional high-performance polymers with the ionene archetype–presenting polymers with alternating functional and ionic elements precisely sequenced along the backbone. The effects of polymer composition on the thermal properties and morphology were analyzed. Five distinct polymer backbones were synthesized and combined with a stoichiometric equivalent of the IL 1-benzyl-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), which were studied to probe the self-assembly, structuring, and contributions of intermolecular forces when IL is added. Furthermore, three polyamide (PA) or polyimide (PI) ionenes with simpler xylyl linkages were interfaced with [Bnmim][Tf2N] as well as a novel amide-linked tris(imidazolium) IL, to demonstrate the structural changes imparted by the inclusion of functional, ionic additives dispersed within the ionene matrix. This work highlights the possibilities for utilizing concepts from small molecules which exhibit supramolecular self-assembly to guide creative design and manipulate the structuring of ionenes.
... [28][29][30] Earlier work by Bara and O'Harra introduced an ew class of imide-and amide-functionalized bisimidazole monomers, which were subsequently polymerized into high-performance imidazolium ionenes, which inspired this investigation probing similarg reener synthetic routes toward ionic polymers for gas separation or 3D printing by upcycling. [31][32][33][34][35][36] Ionenes are ionic polymers that contain ionic moieties directly within the main chain, rather than as pendant groups (asi np olyelectrolytes or ionomers). ...
... Recently,w er eported that the combination of ionenes and polyamides is applicable to formationf or free-standing membranes, fibers for additive manufacture, or for the treatment of microbial infections. [28][29][30][31][32][33][34][35][36]38] H-bonding provided by the amide functionality and ionic interactions between imidazolium moieties were both factors contributing to the thermal and mechanical stabilities of the membranes. [35,36,38] Nevertheless, the conventional synthesis requires terephthaloyl chloride, which is ah azardousc ompound both for environment and for health (Scheme 1A). ...
Imidazolium‐based ionenes are known to be high‐performance materials for a great variety of applications. The preparation of these polymers requires the use of bis‐imidazole starting monomers, which are commonly prepared by using toxic chloride reagents. In this study, bis‐imidazole monomers are synthesized by organocatalytic chemical recycling of discarded plastics through chemical depolymerization. By using poly(ethylene terephthalate) and bisphenol A polycarbonate as starting materials, different monomers containing amide or urea functionalities are prepared to produce high‐molecular‐weight ionic polymers. These novel ionenes show excellent elastomeric and self‐healing behavior, serving as a promising means to expand the exploration of plastic wastes as a source of new materials.
... Recently, we have synthesized polyimide ionene (PI-ionene) and polyamide ionene (PA-ionene) materials for gas sepration membranes, with the combination of functional groups and ionic components yielding flexible yet robust thin films via solvent-casting or melt-pressing. These ionenes incorporate imidazolium cations within the main backbone paired with "free" (i.e., untethered) fluorinated anions, spacing functional groups or high free volume elements [6,8,47]. Ionenes are an form of ionic polymers that is typically synthesized via condensation reactions [48]. ...
... Materials considered to possess state-of-the-art gas separation performance feature certain functional and structural moieties, which may impart higher free volume distribution or promote flexibility and thermal stability. Polyimides [5][6][7][8][9][10], polymers of intrinsic microporosity (PIMs) [11,12], thermally-rearranged polymers (TR) [13][14][15][16], polyamides [17][18][19], and ion-containing polymers [20,21] are classes of polymeric materials which have been prevalent in this research area. Polyamides are another desirable material class as they feature H-bonding, which often produce self-assembled or well-ordered materials due to chain alignment [22][23][24]. ...
... The synthesis of 4-(1H-imidazol-1-yl)aniline (I4A) starting from imidazole and 4-fluoronitrobenzene followed by reduction in EtOH with H 2 over Pd/C was reported in our previous work [47]. 1 H NMR (500 MHz, DMSO-d 6 ) δ 7.95 (s, 1H), 7.48 (s, 1H), 7.22 (d, 2H), 7.01 (s, 1H), 6.64 (d, J = 8.8, 2H), 5.26 (s, 2H). The synthesis of 3-(1H-imidazol-1-yl)aniline "I3A" was synthesized via a similar procedure and was outlined in our previous work [6]. 1 H NMR (360 MHz, DMSO-d 6 ) δ 8.08 (s, 1H), 7.57 (t, J = 1.3 Hz, 1H), 7.13 (t, J = 1.3 Hz, 1H), 7.08 (s, 2H), 6.73 (t, 1H), 6.72-6.67 ...
Here, we report the synthesis and thermophysical properties of seven primarily aromatic, imidazolium-based polyamide ionenes. The effects of varied para-, meta-, and ortho-connectivity, and spacing of ionic and amide functional groups, on structural and thermophysical properties were analyzed. Suitable, robust derivatives were cast into thin films, neat, or with stoichiometric equivalents of the ionic liquid (IL) 1-benzy-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), and the gas transport properties of these membranes were measured. Pure gas permeabilities and permselectivities for N2, CH4, and CO2 are reported. Consistent para-connectivity in the backbone was shown to yield the highest CO2 permeability and suitability for casting as a very thin, flexible film. Derivatives containing terephthalamide segments exhibited the highest CO2/CH4 and CO2/N2 selectivities, yet CO2 permeability decreased with further deviation from consistent para-linkages.
