Thermally crosslinked sulfonated polyethersulfone proton exchange membranes for direct methanol fuel cells

Gil, Seung Chul; Kim, Jin Chul; Ahn, Dahee; Jang, Jin-Sung; Kim, Haekyoung; Jung, Jin Chul; Lim, Seongyop; Jung, Doo‐Hwan; Lee, Wonmok

doi:10.1016/j.memsci.2012.05.064

Cited by 22 publications

(8 citation statements)

References 29 publications

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“…The linear disulfonated BPS copolymers in the graph span a wide range of selectivity and water permeability values; however, the selectivities of the cross-linked sulfonated oligomers remained relatively constant. Similar phenomena have previously been observed in cross-linked materials for use as fuel cell membranes, in which cross-linking simultaneously increased proton conductivity and membrane selectivity (conductivity/methanol permeability) . Similarly, in these studies, cross-linking permitted preparation of sulfonated polysulfones with higher levels of hydrophilicity (i.e., higher degrees of sulfonation) within the oligomers than previously used.…”

Section: Resultssupporting

confidence: 79%

Cross-Linked Disulfonated Poly(arylene ether sulfone) Telechelic Oligomers. 2. Elevated Transport Performance with Increasing Hydrophilicity

Sundell

Jang

Cook

et al. 2016

Ind. Eng. Chem. Res.

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Disulfonated poly(arylene ether sulfone) copolymer membranes are of interest for water purification by desalination. These negatively charged copolymers exhibit lower fouling and greatly improved resistance to oxidants such as chlorinated disinfectants compared to state-of-the-art highly cross-linked aromatic polyamide, porous polysulfone supported thin film composite (TFC) systems. A systematic series of controlled molecular weight 4,4′-biphenol and bisphenol A based partially disulfonated poly(arylene ether sulfone)s were synthesized with terminal amine functionalities via end-capping with m-aminophenol. The stoichiometric balance of the end-capping reagent, bisphenols, and two activated dihalides controlled M n and degree of disulfonation. Oligomers with controlled molecular weights and ionic content were thermally cross-linked with a multifunctional epoxy resin (TGBAM) derived from methylene dianiline. The residual masses from boiling solvent extraction confirmed high gel fractions. The networks had improved salt rejection compared to linear controls due to reduced swelling, and this proved to be a valuable parameter for enhancing transport properties. The cross-linked highly sulfonated copolymers produced the best water purification properties to date observed for disulfonated polysulfone membranes by retaining high salt rejection with enhanced water permeabilities. For example, an epoxy-cross-linked 4,4′-biphenol-based 60% disulfonated polysulfone with an ion exchange capacity (IEC) of 1.85 mequiv/g had a salt rejection of 96.7% and a relatively high hydraulic water permeability of 1.18 (L μm m–2 h–1 bar–1), compared to a linear 4,4′-biphenol-based 40% disulfonated polysulfone with a similar ionic content (IEC = 1.78) that only had a salt rejection of 92.5% and a hydraulic water permeability of 0.62 (L μm m–2 h–1 bar–1).

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Section: Resultssupporting

confidence: 79%

Cross-Linked Disulfonated Poly(arylene ether sulfone) Telechelic Oligomers. 2. Elevated Transport Performance with Increasing Hydrophilicity

Sundell

Jang

Cook

et al. 2016

Ind. Eng. Chem. Res.

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“…Moreover, the DSC analysis for copolymer membranes thermally treated at 240 °C (curve 4) does really indicate that the cross-linking reaction is proceeding since there is a reduction in the area that corresponds to the exothermic cross-linking reaction. Even though it is not the goal of this research to investigate the precise cross-linking mechanisms in the whole range of temperatures, since it could be proceeding according to complex coupling reactions, , it would be interesting to prove that they are already cross-linked under some possible chemical reactions promoted under a vacuum at 240 °C for 1 h. In this regard, Figure summarizes at least two possible cross-linking mechanisms, one that implies a complex coupling reaction through the triple bond in the carbon–carbon atoms (Straus coupling, Glasser coupling) to produce a linear cross-linker and another one that implies simple trimerization reactions among three acetylene end groups to form an aromatic cross-linker . The solubility experiments made in NMP, and also in DMSO, carried out to determine the gel content indeed confirm that the copolymers thermally treated at 150 and 200 °C are completely soluble, indicating that the cross-linking reaction has not proceeded, whereas the copolymers that were thermally treated at 240 °C become insoluble, at 93 wt %, as compared to the initial weight immersed in NMP and DMSO, thus implicating that the propargyl cross-linking reaction has taken place.…”

Section: Results and Discussionmentioning

confidence: 99%

“…In relation to cross-linking, the current literature suggests that the unsaturated groups found in a propargyl moiety favor the cross-linking of the polymer repeating units to get useful materials for diverse applications, i.e., proton exchange membranes, , thermoplastic liquid crystalline polymers, TLCPs, microporous organic polymers for CO 2 capture and H 2 storage, CMPs, phenolic resins, − thermostable polymers for electric applications, cross-linked polypeptoides as an alternative route to natural and synthetic polypeptides, and ionic conducting membranes for gas separation . In parallel, research efforts have also been focused on the evaluation of the selectivity–permeability properties of the so termed thermally rearranged polymer membranes, which possess an outstanding performance due to the formation of microcavities and fractional free volume redistribution upon a change in chemical structure promoted by thermal treatment. − Alternative modifications to produce microcavities in polymers are the incorporation of two to four tert -butyl carbonate groups, BOC, and/or covalent attachment of β-cyclodextrin in polyimides with the goal that upon removal under an appropriate thermal treatment, the decomposition of such thermolabile groups may form the required microcavities, leading to membranes with outstanding performance in selectivity–permeability.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Thermal Cross-Linking and Decomposition of Side Groups to Mitigate Physical Aging in Poly(oxyindole biphenylylene) Gas Separation Membranes

Hernández-Martínez

Ruiz‐Treviño

Ortiz-Espinoza

et al. 2018

Ind. Eng. Chem. Res.

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Physical aging in amorphous polymers causes a decrease in specific volume and thus in the gas transport properties of their membranes. In this work, the effect of simultaneous thermal decomposition of a thermolabile tert-butyl carbonate group, BOC, and cross-linking by a propargyl group (−CH2–CCH) on the gas selectivity–permeability properties of the resulting membranes is studied to learn how membranes with mitigated variations in the gas permeability coefficients with aging time may be produced. The model copolymer is a poly(oxyindole biphenylylene) that bears BOC and propargyl groups, [(PN-BOC) x -(PN-Pr) y ] n . Systematic studies on the structure/processing/property relationship assessed by TGA, DSC, and permeation measurement using pure gases reveal that a single thermal treatment for 1 h at 240 °C on a neat copolymer membrane, 12–20 μm thickness, is enough to produce chemically robust membranes (insoluble in NMP and DMSO) and that are physically more resistant to aging since the permeability reduction rate approaches zero. The cross-linked membranes possess lower gas permeability coefficients with higher ideal selectivity with respect to the corresponding neat copolymer membranes, i.e., the P(H2) decreases from 60 to 42 Barrers but H2/CH4 selectivity increases by a factor of 2 (21 to 40), and in general the selectivity–permeability properties for the gas pairs H2/CH4, O2/N2, and CO2/CH4 do not present drastic variations with aging time at least from 72 to 2000 h.

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“…A wide range of materials as a substitute for Nafion have been described. A major development in this regard is seen in the use of sulfonated aromatic polymer (sulfonated polyimide) [ 17 ], sulfonated poly ether sulfone (SPES) [ 18 ], sulfonated poly (phenylene oxide) (SPPO) [ 19 ] and sulfonated poly ether ether ketone (SPEEK) [ 6 , 20 ]. Recently, SPES and SPEEK have shown potential applications for direct methanol fuel cell due to their cost effectiveness and improved chemical stability [ 21 , 22 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

SPEEK and SPPO Blended Membranes for Proton Exchange Membrane Fuel Cells

Khan

Shanableh

Shahida³

et al. 2022

Membranes

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In fuel cell applications, the proton exchange membrane (PEM) is the major component where the balance among dimensional stability, proton conductivity, and durability is a long-term trail. In this research, a series of blended SPEEK/SPPO membranes were designed by varying the amounts of sulfonated poly(ether ether ketone) (SPEEK) into sulfonated poly(phenylene) oxide (SPPO) for fuel cell application. Fourier transform infrared spectroscopy (FTIR) was used to confirm the successful synthesis of the blended membranes. Morphological features of the fabricated membranes were characterized by using scanning electron microscopy (SEM). Results showed that these membranes exhibited homogeneous structures. The fabricated blended membranes SPEEK/SPPO showed ion exchange capacity (IEC) of 1.23 to 2.0 mmol/g, water uptake (WR) of 22.92 to 64.57% and membrane swelling (MS) of 7.53 to 25.49%. The proton conductivity of these blended membranes was measured at different temperature. The proton conductivity and chemical stability of the prepared membranes were compared with commercial membrane Nafion 117 (Sigma-Aldrich, St. Louis, Missouri, United States) under same experimental conditions. The proton conductivity of the fabricated membranes increased by enhancing the amount of SPPO into the membrane matrix. Moreover, the proton conductivity of the fabricated membranes was investigated as a function of temperature. Results demonstrated that these membranes are good for applications in proton exchange membrane fuel cell (PEMFC).

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Thermally crosslinked sulfonated polyethersulfone proton exchange membranes for direct methanol fuel cells

Cited by 22 publications

References 29 publications

Cross-Linked Disulfonated Poly(arylene ether sulfone) Telechelic Oligomers. 2. Elevated Transport Performance with Increasing Hydrophilicity

Cross-Linked Disulfonated Poly(arylene ether sulfone) Telechelic Oligomers. 2. Elevated Transport Performance with Increasing Hydrophilicity

Simultaneous Thermal Cross-Linking and Decomposition of Side Groups to Mitigate Physical Aging in Poly(oxyindole biphenylylene) Gas Separation Membranes

SPEEK and SPPO Blended Membranes for Proton Exchange Membrane Fuel Cells

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