ACS Publications. Most Trusted. Most Cited. Most Read
Nanophase-Separated Block-co-Polymers Based on Phosphonated Pentafluorostyrene and Octylstyrene for Proton-Exchange Membranes
More

OR SEARCH CITATIONS

My Activity
Publications

Figure 1Loading Img
Download Hi-Res ImageDownload to MS-PowerPointCite This:ACS Materials Lett. 2023, 5, 8, 2039-2046
  • Open Access
Letter

Nanophase-Separated Block-co-Polymers Based on Phosphonated Pentafluorostyrene and Octylstyrene for Proton-Exchange Membranes
Click to copy article linkArticle link copied!

  • Sebastian Auffarth*
    Sebastian Auffarth
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
    * Email: [email protected]
    More by Sebastian Auffarth
    Orcidhttps://orcid.org/0000-0002-6784-9135
  • Maximilian Wagner
    Maximilian Wagner
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    More by Maximilian Wagner
  • Anja Krieger
    Anja Krieger
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    More by Anja Krieger
  • Birk Fritsch
    Birk Fritsch
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    More by Birk Fritsch
    Orcidhttps://orcid.org/0000-0001-7935-2188
  • Linus Hager
    Linus Hager
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
    More by Linus Hager
  • Andreas Hutzler
    Andreas Hutzler
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    More by Andreas Hutzler
    Orcidhttps://orcid.org/0000-0001-5484-707X
  • Thomas Böhm
    Thomas Böhm
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    More by Thomas Böhm
    Orcidhttps://orcid.org/0000-0003-2036-2159
  • Simon Thiele
    Simon Thiele
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
    More by Simon Thiele
    Orcidhttps://orcid.org/0000-0002-4248-2752
  • Jochen Kerres*
    Jochen Kerres
    Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    Chemical Resource Beneficiation Faculty of Natural Sciences, North-West University, Potchefstroom 2520, South Africa
    *Email: [email protected]
    More by Jochen Kerres
Open PDFSupporting Information (1)

ACS Materials Letters

Cite this: ACS Materials Lett. 2023, 5, 8, 2039–2046
Click to copy citationCitation copied!
https://doi.org/10.1021/acsmaterialslett.3c00569
Published June 29, 2023

Copyright © 2023 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Abstract

Click to copy section linkSection link copied!
High Resolution Image
Download MS PowerPoint Slide

Nanophase separation into hydrophobic and hydrophilic domains in commercial perfluorosulfonic acid polymers promotes high conductivity by forming proton-conductive channels within a matrix. To transfer this beneficial phase separation to phosphonic acid functionalized ionomers, we combine phosphonated polypentafluorostyrene and flexible polyoctylstyrene in a di-block-co-polymer. We introduce a stepwise approach, including mesophase simulations, synthesis, and spectroscopic imaging. After the required block lengths were calculated, controlled radical polymerization led to a narrowly distributed block-co-polymer. The respective block-co-polymer membrane outperforms a phosphonated pentafluorostyrene blend concerning conductivity and water uptake. Stained membrane cross-sections revealed bicontinuous nanophase separation in the 13 to 25 nm range in transmission electron microscopy. The ion-conducting phosphonated polymer block assembled into an isotropic, three-dimensional gyroidal network across the membrane. Our stepwise approach is transferable toward other block-co-polymer systems featuring different monomers or functional groups. Applying the proposed principles allows for the prediction of structure-related phase separation while reducing the amount of synthesis work.

This publication is licensed under

CC-BY 4.0 .
  • cc licence
  • by licence
Copyright © 2023 The Authors. Published by American Chemical Society

Subjects

what are subjects
Ion-conducting polymers (ionomers) are part of a wide range of electrolyzers, batteries, and fuel cells, facilitating ion transport between anode and cathode reactions. (1−3) In those applications, their high ion conductivity can be utilized in membranes and electrodes. (4,5) Application-relevant ionomer properties include

  • high conductivity at application temperature

  • high chemical stability against the reactants/products, radicals, humidity and temperature(-changes)

  • high durability against dimensional changes related to swelling, start/shut-down cycles, and pressure deviations in reactant/product feeds

If an ionomer is used as a membrane material, the electric insulation of the anode and cathode, the separation of the reactants and the selective transport of different ionic species are essential. (6−8) Ionomer membranes can be specifically tailored for their respective applications, because of the broad range of possible material modifications.
Nafion and its derivates have emerged as standard materials for hydrogen fuel cells and electrolyzers featuring a fluorinated, aliphatic polymer backbone and sulfonic acid group side chains. (9−11) In particular, Nafion excels in achieving high proton conductivities despite a comparably low ion-exchange capacity (IEC) of under one mmol H+ per gram of polymer. This characteristic relates to a pronounced phase separation in the nanometer range, promoting channels with high local concentrations of water and sulfonic acid. (12,13) Compared to randomly sulfonated copolymers, phase separation of block-co-polymers enhances the conductivity, water uptake, and cell performance. (14,15) Recently, the thiolation of block-co-polymers from polypentafluorostyrene (PPFS) and butylacrylate enabled the preparation of thin films and membranes with distinct nanophase separation between 30 and 96 nm. (16,17) Extensive swelling of the mercaptopropane sulfonate functionalized ionomer was observed in water, but ionic and covalent cross-linking stabilized the membranes. (17)
In general, the presence of water around acidic groups enables high proton conductivity due to distinct hopping and vehicular transport mechanisms. (18) Above 100 °C at ambient pressure, the evaporation of water limits the sufficient humidification of sulfonated polymers required for high conductivities.
Consequently, high-temperature applications above 100 °C often rely on phosphoric acid-doped membranes. (19) The respective ionomers contain a positive or protonated group, which coordinates phosphoric acid and phosphonates. (20,21) General obstacles of phosphonic acid-doped materials include catalyst poisoning by phosphonate anions and acid loss over time. (22,23) The loss of the ion-conducting acid can occur during operation by evaporation above 160 °C or via an exponential water replacement mechanism. (24) Phosphonic acid groups can also be directly attached to a polymer to avoid acid loss over time. In phosphonated polypentafluorostyrene (PWN), the electron-deficient aromatic ring enhances the acidity of the ion-conducting group by stabilizing the corresponding negative charge. (25) Applying atom-transfer radical polymerization, first graft and block-co-polymers of PWN have been reported based on polymer backbones with high molecular weight dispersity and glass transition temperature. (26−28) Unfortunately, PWN, in its dry state, is also very brittle due to its high glass-transition temperature. (29) The mechanical properties can be enhanced by blending them with polybenzimidazole. While the additional acid–base cross-links further stabilize the membrane, the basic benzimidazole groups reduce the number of accessible acid groups for proton transport.
In this publication, we present the mesophase structure simulation-supported, controlled synthesis of a block-co-polymer based on brittle PWN and viscous polyoctylstyrene (POS). After preparation of a diblock-polymer membrane, the conductivity and water uptake were determined. The nanostructure of the membrane was analyzed by scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDXS).
Various solubility parameters can describe the interactions between two blocks within a di-block-co-polymer. In this publication, solubility parameters and molar densities were calculated by forcite calculations (see SI-1). Table 1 shows the respective densities and solubility parameters of different repeating units calculated from an energy minimization of 100 monomers each. We decided to reduce the phosphonation degree to two-thirds in the simulation since fully phosphonated PWN-100 is water-soluble. (25) Figure 1 depicts the nanophase separation from mesostructured simulations of di-block-co-polymers with various lengths based on partly phosphonated PWN and POS in 64·64·64 nm3 cubes. The number of simulated polymer chains is related to the block lengths and their molar volume (see SI-1). Typical for di-block-co-polymers, the ratio between the block lengths of partly phosphonated PWN and POS plays a significant role in the nanostructure. A continuous nanophase of functional groups is required to ensure sufficient conductivity of charges within ion exchange membranes.

Figure 1

Figure 1. Mesostructure simulations of nanophase separation of POS-b-PWN-66 with block lengths of 100:20 (a), 50:50 (b), and 20:100 (c). The simulated cubes consist of 5543 (a), 7763 (b), 7769 (c) distinct POS-b-PWN-66 chains.

High Resolution Image
Download MS PowerPoint Slide
Table 1. Calculated Parameters for Mesostructure Simulations by Forcite Energy Minimization
polymersolubility parameter [(J cm–3)0.5]density [g cm–3]molar mass [g mol–1]molar volume [cm3 mol–1]
phosphonated PFS24.01.6256160
pentafluorostyrene18.61.42194137
octylstyrene17.20.85216254
PWN-6622.21.54235152
PWN-66-POS5.0  203
For proton-exchange membranes, a continuous domain of phosphonic acid groups presents a direct pathway for protons to move through the membrane. Therefore, materials with nanophase separations, as depicted in Figure 1b and c, promise sufficient conductivity. A bicontinuous system, like in Figure 1b, offers adequate conductivity while reducing the amount of brittle PWN. The length adjustment of the polymer blocks allows fine-tuning of the nanophase. Thus, the simulations of this relationship are utilized in the following polymer synthesis.
The mesostructure simulations of the POS-b-PWN-66 derivatives rely on distinct block lengths with a unique molecular weight. Therefore, we aimed to synthesize polymers with a narrow polymer weight distribution to minimize a potential impact on the nanophase separation. The stepwise polymerization of the di-block-co-polymer was realized by a controlled radical polymerization utilizing a reversible addition-fragmentation chain-transfer (RAFT) reagent. Figure 2 shows the synthesis of the block-co-polymer POS-PPFS and the subsequent phosphonation of X% pentafluorostyrene units to POS-PWN-X. End-group and backbone analyses by nuclear magnetic resonance (NMR) spectroscopy (see SI-2) and size-exclusion chromatography (GPC) were used to calculate the block lengths within the di-block-co-polymer POS-PPFS (Table 2).

Figure 2

Figure 2. Stepwise synthesis of POS-PPFS by RAFT-polymerization and partial phosphonation.

High Resolution Image
Download MS PowerPoint Slide
Table 2. Block Lengths from GPC/NMR Analysis and Glass Transition Temperatures of Block-co-polymer POS-b-PPFS
polymer-blockMn/Mw [kg mol–1]dispersity Đblock length GPC-Mwblock length 1H-NMRTg [°C]
polyoctylstyrene (POS)12.8/13.31.0376250 
polypentafluorostyrene (PPFS)  5554 
POS-b-PPFS21.1/24.01.137  –19/101
While only the synthesis of the first block POS required an additional RAFT reagent, azobis(isobutyronitrile) (AIBN) initiated the polymerizations of both polymer blocks. The RAFT-terminated POS was isolated as a yellow, sticky oil since the alkyl chains in the para-position disturb POS’s crystallization, lowering the glass transition temperature. (30) For calculation of the block lengths, the degree of polymerization (DP, average number of monomer units per polymer) was determined. The terminal CH3-group of the RAFT reagent was used as a reference for calculating the block length by 1H-NMR analysis (see SI-2). Compared to the block length by end-group analysis, GPC’s mass average corresponds to a slightly higher number of octylstyrene units. Next to minor chain termination by recombination, this finding relates to GPC’s polystyrene standard calibration and the increased hydrodynamic diameter of POS.
Nevertheless, the low dispersity of under 1.04 underlines the narrow weight distribution of the controlled radical polymerization. For the second block of PPFS, the POS block was utilized as a macro-RAFT-reagent. By comparing backbone integrals, NMR analysis proves the successful synthesis of the di-block-co-polymer POS-b-PPFS with equal block sizes (see SI-2). Deriving the difference in mass average from GPC, the block lengths for the PPFS block are similar regardless of the analysis technique. While the dispersity of POS-b-PPFS increased slightly, the diblock exhibits the expected glass transition temperatures of around −20 and 100 °C (see SI-4). (31,32)
The PPFS part of the diblock-polymer was phosphonated by para-fluor substitution with tris(trimethylsilyl)-phosphite (TSP). The stoichiometric equivalents of the TSP influence the phosphonation degree X, as described in the literature for the phosphonation of pure PPFS. (33) Additional factors that impact the phosphonation degree include influences of additional solvent and water/oxygen impurities, which quench the TSP during or before the reaction. To monitor the phosphonation degree X against time, we traced the reaction by 19F-NMR (see SI-3). Since TSP substitutes the para-fluorine atom, the degree of phosphonation can be calculated from the integrals of the respective peaks. The solvent DMAc seemed to limit the phosphonation degrees to around 60% despite 1.2 equiv of TSP. During the subsequent workup, the protecting groups were hydrolyzed. For higher phosphonation degrees, pure TSP was used both as a reactant and as a solvent for POS-b-PPFS. The excess of TSP leads to shorter reaction times of a few hours (see SI-3). However, (nearly) complete phosphonation of PWN-homopolymers causes water solubility, preventing their application in aqueous conditions. A fully phosphonated POS-b-PWN-100 derivate showed good film-forming properties but disintegrated into a turbid dispersion due to the excessive water uptake of the PWN-100 block.
The block-co-polymer POS-b-PWN-60 forms a clear, viscous gel in dimethylsulfoxide (DMSO). By the addition of tetrahydrofuran (THF), the viscosity of the polymer solution decreases drastically to allow membrane manufacturing by solution casting. This observation relates to the different solubilities of the hydrophobic and hydrophilic blocks. Unlike pristine PWN, the POS-b-PWN-60 membrane features two glass transition temperatures at −20 and 265 °C (see SI-4). The membrane POS50-b-PWN-6054 is relatively sticky to various surfaces, such as a polyethylene storage bag. When the POS ratio in the presented block-co-polymer is increased, the stickiness is expected to increase until the membrane becomes a viscous oil. When the PPFS block is enlarged to around 185 units, the water uptake of the PWN part, which is responsible for membrane disintegration, needs to be contradicted. The phosphonation degree was reduced to 42%. While the decreased proportion of POS reduced the stickiness of POS50-b-PWN-42185, the general mechanical handling of the membrane was similar to POS50-b-PWN-6054. The material’s brittleness corresponds to Young’s modulus, which was analyzed by dynamic mechanical analysis (see SI-5). As expected, pure PWN-75 has a higher Young’s modulus of 275 ± 42 MPa than the POS-b-PWN-60 with 70 ± 7 MPa at 0% relative humidity. With its −20 °C glass transition temperature, the POS block softens the respective membrane, resulting in a lower overall brittleness/Young’s modulus. At high relative humidities of around 90% (maximum of our testing device), the Young’s moduli of PWN-75 and POS-b-PWN-60 are very close within the same order of magnitude and decrease by 98.6% and 89.3%, respectively. Since their high phosphonation degree, PWN-75 and POS-b-PWN-60 absorb water, significantly lowering the brittleness. However, the absolute change is lower for POS-b-PWN-60 because the POS block causes a general softening regardless of the precise relative humidity. While these results prove the softening effect of the flexible POS on the brittle PWN, additional cross-linking of the polymer chains may be incorporated in the future to achieve elastomeric properties of the block-co-polymer.
Table 3 compares the POS-b-PWN-60 membrane’s properties (see experimental details in SI-6) to Nafion and a blend of PWN-75 and polyvinylidene fluoride (PVDF). The through-plane membrane conductivities at room temperature of POS-b-PWN-60 and the PVDF-PWN-75-blend are lower than for the commercial Nafion 211 reference. This finding is expected and relates to the lower acidity of phosphonic acid groups compared with the sulfonic acids found in Nafion. Like phosphoric acid, phosphonated ionomers can simultaneously act as a proton acceptor and donor, reducing reliance on water to ensure proton conductivity. (34,35) The phosphonated PWN also features higher thermal stability than the sulfonated equivalent (Tdegradation: 391 °C for PWN/351 °C for sulfonated PPFS). (36) Phosphonated ionomers are therefore used in low humidity applications, especially. (37) A higher number of acidic groups generally increase the number of charge carriers in proton-exchange membranes, thereby enhancing conductivity. The ratio of the PVDF and PWN-75 was set to mimic the number of charge carriers (IECdirect) of POS-PWN-60 to allow a direct comparison of conductivity and swelling. Despite their same IECdirect (see experimental details in SI-6), POS-b-PWN-60 has a 50% higher conductivity than the PVDF-PWN-75. As for Nafion, distinct nanophase separation produces pathways for proton transport by locally increasing the concentration of acidic groups. The PVDF-PWN-75-membrane has a far higher water uptake of 123 wt % at 85 °C, whereas the uptake of Nafion and POS-b-PWN-60 is around 40 wt % and 70 wt % (see Table 3). While the water uptake is higher than for commercial Nafion membranes, the nonpolar POS block reduces the water uptake of POS-b-PWN-60 significantly compared to PVDF-PWN-75.
Table 3. Membrane Properties of POS-b-PWN-60, PVDF-PWN-75, and Nafion 211
membraneconductivity [mS cm–1]water uptake (wt %) at 25/60/85 °CIECdirect [mmol g–1]
POS-b-PWN-6033 ± 227/44/711.22
PVDF-PWN-7521 ± 144/69/1231.25
N21155 ± 415/36/410.91*
*

Calculated from the equivalent weight.

In general, high water absorption directly correlates with dimensional swelling and wider proton conductive channels. Despite the lower water uptake of POS-b-PWN-60, the additional nanostructure increases the local density of the proton conducting groups. This effect seems to overcompensate for the influence of the reduced water absorption on the conductivity. In literature, the impact of the copolymer architecture on the conductivity in regard to hydration has been demonstrated for different sulfonated membranes before. (38,39) A sulfonated block copolymer from styrene and isobutylene polymer (48% sulfonation degree, IECdirect 1.28 mmol g–1) featured a conductivity at room temperature of around 25 mS cm–1 and a water uptake of 75 wt % (Nafion 117: 27 mS cm–1, 25 wt %). (14) Utilizing an in-plane conductivity procedure, a copolymer consisting of PVDF/hexafluoropropylene and partially sulfonated styrene blocks with an IECdirect of 1.18 mmol g–1 had a conductivity of 80 mS cm–1 and a water-uptake of around 90 wt % (Nafion 117: 72 mS cm–1, 29 wt %). (40) While the conductivities of sulfonated, phase-separated membranes equal that of their respective Nafion references, the water uptake at room temperature was significantly higher than that for POS-b-PWN-60. Compared to the phosphonated PVDF-PWN-75 blend, the block-co-polymer membrane features a conductivity increase of 50% despite a 40% decrease in swelling. These results clearly show the potential of our block-co-polymer approach toward high-performance membrane alternatives. The sulfonation of the block-co-polymer is currently being investigated in our laboratories to provide nanostructure-enhanced membranes for low-temperature applications.
To prove the formation of distinct nanophases, the POS-b-PWN-60 membrane was stained with Pb2+-ions and an ultramicrotomy cross-section was analyzed by high-angle annular dark field (HAADF) STEM imaging. Pb2+-staining increases the Z-contrast in HAADF-STEM due to the Rutherford-like scattering. The HAADF-STEM micrographs in Figure 3 depict a clear nanophase separation of a bright, continuous, honeycomb-like structure within a darker phase. Nanophases with highly polar constituents, like the polar PWN-60 block, accumulate the charged Pb2+-ions while they are excluded from the nonpolar POS block. As the scattering at the Pb2+-ions creates a bright image contrast, the darker domains correspond to the POS block.

Figure 3

Figure 3. Nanophase separation in POS-b-PWN-60. (a) HAADF-STEM images of the Pb2+ stained membrane cross-section and diffractogram for nanostructure size determination. (b) Mean atomic-bond lengths from SAED. (c) Chemical structure of the polymer from synthesis. (d) Nanophase simulation of POS50-b-PWN-6650 with the same parameters as those in Figure 1. Similar to (a), the dark parts correspond to the nonpolar POS-rich phase. (e) Structure domains highlighted in HAADF image and corresponding EDXS images for fluorine, lead, phosphorus, and carbon.

High Resolution Image
Download MS PowerPoint Slide
As mentioned, the dark and bright domains consist of nonpolar and polar blocks, respectively. The different shades within the TEM images (e.g., visible in Figure 3a) can be explained by the section thickness of the sample, with a nominal thickness of 75 nm. Consequently, the transmission images contain overlaps between polar and nonpolar domains. The interconnection of bright domains between dark, nonpolar domains forms a gyroidal, three-dimensional network. Since this network consists of the polar PWN-60 block, isotropic proton transport occurs through the phosphonic groups. In contrast, lamellar or similar nanophases often align parallel to the fabrication direction (here, membrane casting), negatively affecting the perpendicular through-plane conductivity. (41)
At high magnification, the bright intensity at the interphase between the nonpolar and polar domains only decays gradually. This observation may be explained by staining artifacts and ultimately hinders the direct measurement of domain sizes from STEM images. Therefore, the average sizes of the domains were extracted from the diffractograms (see inset in Figure 3a) of the HAADF-STEM images. The nonpolar regions have an average size of 24.7 ± 9.5 nm, whereas polar domains are slightly smaller with an average size of 12.7 ± 2.5 nm (marked as np/p in Figure 3e, respectively). In addition, a nanostructure size of 2.3 ± 1.3 nm (visible in Figure 3a at higher magnification) was extracted, which might relate to agglomerations of octylstyrene repeating units or the congregation of multiple phosphonic acid groups within the polar region. Additional selected area electron diffraction (SAED) was performed to obtain information about potential smaller structure sizes. The corresponding selected area bright field TEM micrograph is depicted in SI-7. By least-squares fitting of background-corrected, polar-integrated radial intensity profiles, (42) structure sizes in the range of various inter-/intramolecular bond lengths were identified (see Figure 3b).
Compared to the simulation of an ideal 50–50 co-block-polymer (Figure 3d), the cross-section of the actual polymer POS-b-PWN-60 (chemical structure depicted in Figure 3c) appears to have slightly larger domain sizes. Although still on the same order of magnitude, the deviation in the transmission images also relates to the domain’s random orientation within the sample section and blurred domain edges (see SI-8). Slight deviations from a broader polymer weight distribution and lower phosphonation might also influence the precise form of the nanophases in the STEM micrographs. The observed honeycomb structure of the polar domains could relate to other interactions within the distinct nanophases, which were not considered in the simulation. Nevertheless, our mesophase simulations of diblock polymers accurately predicted the bicontinuous, phase-separated structure and successfully guided our polymer synthesis.
Additional EDXS imaging in Figure 3e confirms the assignment of POS and PWN-60 domains. The intensities of fluorine and phosphorus, only present in the PWN-60 block, correlate with the bright regions of the micrographs. As expected, the intensity of the lead emerges in the same regions, highlighting the polarity of the phases. In contrast, differences in carbon intensity, present in both parts of the block-co-polymer, are minor. The higher fraction of carbon in the POS block (89 wt % C) compared to the PWN-60 block (42 wt % C without lead staining) results in slightly higher intensity in the nonpolar domains.
To conclude, we present the combination of simulation, synthesis, and (spectroscopic) imaging of a block-co-polymer for application as a proton-exchange membrane. After calculating the solubility parameters for mesostructure analysis, we estimated the required block sizes for a bicontinuous polymer nanophase. Controlled RAFT-polymerization allowed us to realize the proposed diblock backbone structure with two distinct glass transition temperatures. After partial phosphonation, membranes were manufactured by solution casting. Compared with a PWN75-PVDF blend, the diblock-polymer exhibited improved conductivity and water uptake. The proposed nanostructure of a cross-section was verified by HAADF-STEM imaging and EDXS, where a gyroidal network of ion-conducting domains was found. The isotropic distribution of these domains enables a high ion conductivity. In the future, our simulation-guided synthesis approach may help in the manufacture of membranes from ionomers suffering from high brittleness. We look forward to expanding our block-co-polymer systems to other nonpolar polymer blocks and further ion-conducting functional groups.

Experimental Methods

Click to copy section linkSection link copied!
Octylstyrene was destabilized by an alumina oxide column. All of the other chemicals were used without further purification.

Synthesis of the Block-co-polymer POS-PPFS

DDMAT (97.0 mg, 0.26 mmol, 1 equiv) and AIBN (8.7 mg, 0.05 mmol, 0.2 equiv) were dissolved in a mixture of DMF (3 mL) and 4-n-octylstyrene (4.5 g, 5.4 mL, 0.02 mol, 80 equiv), and the reaction mixture was degassed by three freeze–pump–thaw cycles to remove oxygen residuals. The reaction mixture was stirred at 85 °C for three days. The viscous yellow raw product was dissolved in ethyl acetate (10 mL) and precipitated in methanol twice. The viscous oil was separated, and volatile residual solvents/monomer were removed at 80 °C under high vacuum. The poly(4-octylstyrene) (POS, macro-chain-transfer-reagent, 2.2 g, 0.18 mmol, 1 equiv) was dissolved in destabilized THF and was added to 1,2,3,4,5-pentafluorostyrene (2.1 g, 1.5 mL, 0.01 mol, 60 equiv) and AIBN (6.0 mg, 0.04 mmol, 0.2 eq). The reaction mixture was stirred at 85 °C for 35 h. The viscous solution was diluted in THF (5 mL) and precipitated in isopropanol twice. The yellowish powder POS-PPFS (2.1 g) was filtered off and dried overnight at 60 °C in a vacuum oven.

Phosphonation of the Block-co-polymer POS-PPFS

For partial phosphonation, POS-PPFS (2.0 g, 5.19 mmol PFS-units, 1 equiv) was dissolved in DMAc, and the phosphonation reagent TSP (2.0 g, 2.3 mL, 0.07 mmol, 1.26 equiv) was added portion-wise. Under an argon atmosphere, the reaction mixture was heated to 170 °C for 48 h. For full phosphonation, POS-PPFS (1 equiv) can be dissolved in the phosphonation reagent TSP (6 eq). Under an argon atmosphere, the reaction mixture was heated up to 170 °C for 20 h. In both cases, the crude product was cooled to room temperature and precipitated in acetonitrile. The polymer was filtered off and consecutively hydrolyzed in water (100 °C) and aqueous HCl (1 M, 60 °C) for one day each. The polymer suspension was precipitated once in acetonitrile and washed with water until a neutral pH. The phosphonated polymer POS-PWN-60 was dried at 95 °C for 18 h and at 60 °C for 2 h in a vacuum oven to yield a yellow solid (1.3 g).

Membrane Casting

After dissolving the di-block-co-polymer in DMSO (5 wt % solution), THF (20 wt %) was added to the solution to decrease the viscosity for doctor blade casting. After adding THF to the viscous polymer solution in DMSO (5 wt %), the final polymer concentration is around 4.2 wt %. The casted thin film was predried sequentially at 45 and 65 °C for 45 min each to evaporate the THF slowly. After, the thin film was dried at 85 °C for 2 h. To ensure complete evaporation of the solvent, the membrane was further dried at 110 °C overnight. A gap height of 900 μm resulted in a 32 μm thick membrane after detachment in water. The PVDF-PWN-75 blend membranes were prepared by mixing PVDF (10 wt %) and PWN-75 (5 wt %) solutions in DMAc. The PWN-75 was synthesized according to the literature. (25) The ratio of PVDF and PWN-75 was calculated according to the measured IECdirect of the membrane POS-PWN-60.

Supporting Information

Click to copy section linkSection link copied!

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmaterialslett.3c00569.

  • Simulation of POS-PWN-66 nanophase; NMRs of the block-co-polymers; DSC curves of POS-PPFS and POS-PWN60; DMA measurements of POS-b-PWN-60 and PWN-75; experimental details of membrane characterization; experimental details of nanophase imaging; analysis of STEM and simulation images of POS-PWN; NMR and GPC methods (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

Click to copy section linkSection link copied!
  • Corresponding Authors
    • Sebastian Auffarth - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany;  Orcidhttps://orcid.org/0000-0002-6784-9135;  Email: [email protected]
    • Jochen Kerres - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Chemical Resource Beneficiation Faculty of Natural Sciences, North-West University, Potchefstroom 2520, South Africa;  Email: [email protected]
  • Authors
    • Maximilian Wagner - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    • Anja Krieger - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany
    • Birk Fritsch - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Orcidhttps://orcid.org/0000-0001-7935-2188
    • Linus Hager - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
    • Andreas Hutzler - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Orcidhttps://orcid.org/0000-0001-5484-707X
    • Thomas Böhm - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Orcidhttps://orcid.org/0000-0003-2036-2159
    • Simon Thiele - Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Cauerstr. 1, 91058 Erlangen, Germany;  Department of Chemical and Biological Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany;  Orcidhttps://orcid.org/0000-0002-4248-2752
  • Author Contributions

    All authors have approved the final version of the manuscript. CRediT: Sebastian Auffarth conceptualization, methodology, investigation, data curation, writing - original draft, visualization; Maximilian Wagner methodology, software, writing - review & editing; Anja Krieger investigation, visualization, writing - review & editing; Birk Fritsch investigation, visualization, writing - review & editing; Linus Hager conceptualization, writing - review & editing; Andreas Hutzler investigation, visualization, writing - review & editing; Thomas Böhm investigation, writing - review & editing; Simon Thiele funding acquisition, supervision, writing - review & editing; Jochen Kerres conceptualization, supervision, writing - review & editing

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

Click to copy section linkSection link copied!

The authors acknowledge financial support from the Bavarian Ministry of Economic Affairs, Regional Development and Energy.

Abbreviations

Click to copy section linkSection link copied!
IEC

ion-exchange capacity

PPFS

polypentafluorostyrene

PWN-X

X% phosphonated polypentafluorostyrene

POS

polyoctylstyrene

STEM

scanning transmission electron microscope

EDXS

energy-dispersive X-ray spectroscopy

RAFT

reversible addition–fragmentation chain-transfer

NMR

nuclear magnetic resonance

GPC

gel permeation chromatograph

AIBN

azobisisobutyronitrile

DP

degree of polymerization

DDMAT

2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid

DMSO

dimethylsulfoxide

THF

tetrahydrofuran

TSP

tris(trimethylsilyl)phosphite

HAADF

high-angle annular dark-field imaging

DMF

dimethylformamide

DMAc

dimethylacetamide

DSC

differential scanning calorimetry

SAED

selected area electron diffraction

References

Click to copy section linkSection link copied!

This article references 42 other publications.

  1. 1
    Kerres, J. A. Design Concepts for Aromatic Ionomers and Ionomer Membranes to be Applied to Fuel Cells and Electrolysis. Polymer Reviews 2015, 55, 273– 306,  DOI: 10.1080/15583724.2015.1011754
    Google Scholar
    1
    Design Concepts for Aromatic Ionomers and Ionomer Membranes to be Applied to Fuel Cells and Electrolysis
    Kerres, Jochen A.
    Polymer Reviews (Philadelphia, PA, United States) (2015), 55 (2), 273-306CODEN: PRPPCY; ISSN:1558-3716. (Taylor & Francis, Inc.)
    In this review the research of the author's group regarding the optimization of the chem. stability and properties of arom. ion-exchange polymers by suitable and systematic synthesis of electron-deficient monomer building blocks and by their (co) polymn. into highly stable arom. ionomers are presented. Moreover, the prepn. of phys. or covalently cross-linked ion-exchange membranes by blending these ionomers with each other and with suitable com. polymers to finally afford ion-exchange membranes with properties tailored for electromembrane applications such as fuel cells, electrolysis, and redox-flow batteries are described.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXotFCgu7o%253D&md5=25f05be9f52e0eae711007e652c1dc51
  2. 2
    Chromik, A.; dos Santos, A. R.; Turek, T.; Kunz, U.; Häring, T.; Kerres, J. Stability of acid-excess acid–base blend membranes in all-vanadium redox-flow batteries. J. Membr. Sci. 2015, 476, 148– 155,  DOI: 10.1016/j.memsci.2014.11.036
    Google Scholar
    2
    Stability of acid-excess acid-base blend membranes in all-vanadium redox-flow batteries
    Chromik, Andreas; dos Santos, Antonio R.; Turek, Thomas; Kunz, Ulrich; Haering, Thomas; Kerres, Jochen
    Journal of Membrane Science (2015), 476 (), 148-155CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
    In this contribution the performance of 2 acid-base blend membranes in an all-V redox-flow battery (VRFB) is studied. The 1st membrane is a nonfluorinated acid-base blend membrane composed of a sulfonated poly(arylene ether sulfone) and polybenzimidazole PBIOO, the 2nd, partially fluorinated, membrane is composed of a sulfonated polymer from decafluorobiphenyl and bisphenol AF and the polybenzimidazole F6PBI. It turns out from gel permeation chromatog. expts. that the mol. wt. of both membranes degrades in VRFB. However the partially fluorinated membrane (S1B1) is more stable in VRFB, which can be seen in the no. of charge/discharge cycles, while the nonfluorinated membrane S2B2 fails after 137 cycles, the partially fluorinated membrane S1B1 survives 200 cycles. Also, the percentage of residual mol. wt. of the nonfluorinated membrane after failure (after 137 cycles) is 34.0%, and of the partially fluorinated membrane (after 200 cycles) is 58.8%, resp. Both membranes show better peak power densities than a Nafion 117 membrane operated in VRFB under the same conditions. In contrast to Nafion 117 and S2B2, the S1B1 membrane shows stable voltage and energy efficiency within the 1st 60 charge/discharge cycles. Also, the Coulomb efficiency of the S1B1 membrane was higher than that of S2B2 and Nafion 117, resp., being nearly 100%.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVems7zE&md5=3df52265f5f223043dea4cdcca101893
  3. 3
    Park, J. E.; Kim, J.; Han, J.; Kim, K.; Park, S.; Kim, S.; Park, H. S.; Cho, Y.-H.; Lee, J.-C.; Sung, Y.-E. High-performance proton-exchange membrane water electrolysis using a sulfonated poly(arylene ether sulfone) membrane and ionomer. J. Membr. Sci. 2021, 620, 118871,  DOI: 10.1016/j.memsci.2020.118871
    Google Scholar
    3
    High-performance proton-exchange membrane water electrolysis using a sulfonated poly(arylene ether sulfone) membrane and ionomer
    Park, Ji Eun; Kim, Junghwan; Han, Jusung; Kim, Kihyun; Park, SungBin; Kim, Sungjun; Park, Hyun S.; Cho, Yong-Hun; Lee, Jong-Chan; Sung, Yung-Eun
    Journal of Membrane Science (2021), 620 (), 118871CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
    Sulfonated poly(arylene ether sulfone) with degree of sulfonation of 50 mol.% (SPAES50) was synthesized for the prepn. of a hydrocarbon-based membrane and ionomer, for application to proton-exchange membrane water electrolysis (PEMWE) as an alternative to Nafion. The SPAES50 membrane showing the excellent phys. and electrochem. properties as well as the SPAES50-based ionomer (P50) were prepd. and applied to PEMWE to evaluate its performance. The effects of the membrane thickness and ionomer content were also investigated to realize high-performance SPAES-based PEMWE. The proposed SPAES-based PEMWE showed higher performance than that of com. PEMWE with a Nafion membrane and ionomer. Addnl., this is the best performance reported to date, and it is attributed to the low ohmic resistance caused by the high proton cond. of SPAES50 membrane and the small membrane thickness (20 μm). Therefore, we demonstrate the great potential of SPAES50 as a hydrocarbon-based membrane and ionomer in PEMWE.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXitlWnsLnJ&md5=b6a5ff00056126b2ea3aa1e6026e03ba
  4. 4
    Bernt, M.; Gasteiger, H. A. Influence of Ionomer Content in IrO2/TiO2 Electrodes on PEM Water Electrolyzer Performance. J. Electrochem. Soc. 2016, 163, F3179– F3189,  DOI: 10.1149/2.0231611jes
    Google Scholar
    4
    Influence of ionomer content in IrO2/TiO2 electrodes on PEM water electrolyzer performance
    Bernt, Maximilian; Gasteiger, Hubert A.
    Journal of the Electrochemical Society (2016), 163 (11), F3179-F3189CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)
    In this study, the effect of ionomer content in IrO2/TiO2 anode electrodes for a proton exchange membrane (PEM) electrolyzer is investigated (Nafion 212 membrane; 2.0 mg Ir cm-2/0.35 mg Pt cm-2 (anode/cathode)) and the contributions of ohmic losses, kinetic losses, proton transport losses in the electrodes, and mass transport losses to the overall cell voltage are analyzed. Electrolysis tests are performed with an inhouse designed high pressure electrolyzer cell at differential pressure up to 30 bar. The best performance is obtained for an ionomer content of 11.6 wt% and a cell voltage of 1.57 V at 1 A cm-2 and less than 2 V at 6 A cm-2 (ambient pressure, 80°). Performance losses at lower ionomer contents are the result of a higher proton conduction resistance. For higher ionomer contents, on the other hand, performance losses can be related to a filling of the electrode void vol. by ionomer, leading to a higher O2 mass transport resistance, an increased electronic contact resistance, and the electronic insulation of parts of the catalyst by ionomer. At high pressure operation, the performance cor. by the shift of the Nernst voltage increases with H2 pressure and a new explanation is proposed for this effect.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXpsleisbw%253D&md5=f7c78ad670ca65d89047bf0cd1d7806d
  5. 5
    Kerres, J. A. Development of ionomer membranes for fuel cells. J. Membr. Sci. 2001, 185, 3– 27,  DOI: 10.1016/S0376-7388(00)00631-1
    Google Scholar
    5
    Development of ionomer membranes for fuel cells
    Kerres, J. A.
    Journal of Membrane Science (2001), 185 (1), 3-27CODEN: JMESDO; ISSN:0376-7388. (Elsevier Science B.V.)
    A review with 78 refs. of state-of-the-art of membrane development for proton-conductive polymer (composite) membranes for fuel cells. For prepn. of the polymers, processes have been developed for sulfonated arylene main-chain polymers as well as for arylene main-chain polymers contg. basic N-contg. groups, including a lithiation step. Covalently cross-linked polymer membranes have been prepd. by alkylation of the sulfinate groups of sulfinate group-contg. polymers with α,ω-dihalogenoalkanes. The advantage of the covalently cross-linked ionomer membranes was their dimensional stability even at temps. of 80-90°; their main disadvantage is their brittleness when drying out, caused by the inflexible covalent network. Sulfonated and basic N-contg. polymers have been combined to acid-base blends contg. ionic cross-links. The main advantage of this membrane type is its flexibility even when dried out, its good-to-excellent thermal stability, and the numerous possibilities to combine acidic and basic polymers to blend membranes having fine-tuned properties. The main disadvantage of this membrane type is the insufficient dimension stability at temps. greater than 70-90°, caused by breakage of the ionic cross-links. Some of the acid-base blend membranes are applied to H2 membrane fuel cells and to direct methanol fuel cells up to 100°, yielding the result that these membranes show very good perspectives for the membrane fuel cell application.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjtFCrs74%253D&md5=9605d7a7a1127bdde038c3f1cf0b01b5
  6. 6
    Inaba, M.; Kinumoto, T.; Kiriake, M.; Umebayashi, R.; Tasaka, A.; Ogumi, Z. Gas crossover and membrane degradation in polymer electrolyte fuel cells. Electrochim. Acta 2006, 51, 5746– 5753,  DOI: 10.1016/j.electacta.2006.03.008
    Google Scholar
    6
    Gas crossover and membrane degradation in polymer electrolyte fuel cells
    Inaba, Minoru; Kinumoto, Taro; Kiriake, Masayuki; Umebayashi, Ryota; Tasaka, Akimasa; Ogumi, Zempachi
    Electrochimica Acta (2006), 51 (26), 5746-5753CODEN: ELCAAV; ISSN:0013-4686. (Elsevier B.V.)
    H crossover measurements and durability tests of a single cell under open-circuit conditions were carried out to study membrane degrdn. in polymer electrolyte fuel cells (PEFCs). The limiting c.d. for H crossover was ∼0.8 mA/cm2 at 80° under atm. pressure - gas crossover increased with an increase in cell temp., humidity and H pressure. Under open-circuit conditions, the perfluorinated ionomer electrolyte membrane deteriorated significantly although no net electrochem. reactions took place at the cathode and anode. The mechanism for membrane degrdn. is discussed in terms of heat generation and H2O2 formation upon gas crossover and the resulting catalytic combustion. The latter is the primary reason through which H2O2 is formed by gas crossover of O and the resulting catalytic combustion at the anode. It was inferred that reactive O radicals (HO· and HO2·) were formed in the presence of minor impurities such as Fe2+ and Cu2+ which can accelerate membrane degrdn.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XotVaqtL0%253D&md5=8ac5ae7ddb0b673ac501fb6ba0c02e00
  7. 7
    Auffarth, S.; Dafinger, W.; Mehler, J.; Ardizzon, V.; Preuster, P.; Wasserscheid, P.; Thiele, S.; Kerres, J. Cross-linked proton-exchange membranes with strongly reduced fuel crossover and increased chemical stability for direct-isopropanol fuel cells. J. Mater. Chem. A 2022, 10, 17208– 17216,  DOI: 10.1039/D2TA03832C
    Google Scholar
    7
    Cross-linked proton-exchange membranes with strongly reduced fuel crossover and increased chemical stability for direct-isopropanol fuel cells
    Auffarth, Sebastian; Dafinger, Willibald; Mehler, Julia; Ardizzon, Valeria; Preuster, Patrick; Wasserscheid, Peter; Thiele, Simon; Kerres, Jochen
    Journal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (33), 17208-17216CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)
    Isopropanol fuel cells offer an attractive way to provide elec. energy from a liq., easily transportable fuel without producing significant amts. of CO2. The oxidn. product acetone can be easily hydrogenated back to isopropanol to close the storage cycle, thereby avoiding the sophisticated handling of fugitive mol. hydrogen. Until now, direct-isopropanol fuel cells (DIFC) usually rely on various perfluorosulfonic acid ionomers, like Nafion, which are costly and have an unfavorable high fluorine content. Addnl., the dissoln. of Nafion in isopropanol/acetone/water solns. within resp. applications has prevented the long time operation of DIFCs so far. The swelling of those ionomers during operation promotes fuel crossover and reduces the systems overall energy efficiency. This study uses ionic crosslinking of polymer blends to manuf. chem. stable membranes and introduces a new click-like covalent crosslinking strategy for ion exchange polymers. Compared to Nafion XL, the manufd. membranes increase the max. power d. by up to 10%, resist a dissoln. stress test up to 84 w% and reduce the detected isopropanol/acetone crossover up to 75/100% during fuel cell operation. Consequently, the material can be considered a major step toward the tech. implementation of isopropanol fuel cell technologies.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XitVOgsLnF&md5=a871be6d8c634200d64948d8fc828232
  8. 8
    Kreuer, K.-D.; Münchinger, A. Fast and Selective Ionic Transport: From Ion-Conducting Channels to Ion Exchange Membranes for Flow Batteries. Annu. Rev. Mater. Res. 2021, 51, 21– 46,  DOI: 10.1146/annurev-matsci-080619-010139
    Google Scholar
    8
    Fast and Selective Ionic Transport: From Ion-Conducting Channels to Ion Exchange Membranes for Flow Batteries
    Kreuer, Klaus-Dieter; Muenchinger, Andreas
    Annual Review of Materials Research (2021), 51 (), 21-46CODEN: ARMRCU; ISSN:1531-7331. (Annual Reviews)
    This review discusses selective and fast transport of ionic species (ions and their assocs.) through systems as diverse as ion-conducting transmembrane proteins and ion exchange membranes (IEMs) in aq. environments, with special emphasis on the role of electrostatics, specific chem. interactions, and morphol. (steric effects). Contrary to the current doctrine, we suggest that properly balanced ion-coordinating interactions are more important than steric effects for selective ion transport in biol. systems. Steric effects are more relevant to the selectivity of ionic transport through IEMs. As a general rule, decreased hydration leads to higher selectivity but also to lower transport rate. Near-perfect selectivity is achieved by ion-conducting channels in which unhydrated ions transfer through extremely short hydrophobic passages sepg. aq. environments. In IEMs, ionic species practically keep their hydration shell and their transport is sterically constrained by the width of aq. pathways. We discuss the trade-off between selectivity and transport rates and make suggestions for choosing, optimizing, or developing membranes for technol. applications such as vanadium-redox-flow batteries.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1alu7vE&md5=2d61e67e4ff43304025212e5177e094f
  9. 9
    Banerjee, S.; Curtin, D. E. Nafion® perfluorinated membranes in fuel cells. Journal of Fluorine Chemistry 2004, 125, 1211– 1216,  DOI: 10.1016/j.jfluchem.2004.05.018
    Google Scholar
    9
    Nafion perfluorinated membranes in fuel cells
    Banerjee, Shoibal; Curtin, Dennis E.
    Journal of Fluorine Chemistry (2004), 125 (8), 1211-1216CODEN: JFLCAR; ISSN:0022-1139. (Elsevier B.V.)
    A review. A no. of technologies have been demonstrated to be feasible for generation of power from fuel cells over the last several years. Proton exchange membranes have emerged as an essential factor in the technol. race. DuPont has supplied Nafion perfluorinated membranes in fuel cells for space travel for more than 35 yr and they have played an integral part in the success of recent work in portable, stationary and transportation applications. The basis for proton exchange membrane fuel cell emergence and DuPont technol. utilization is discussed.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXms1yrt70%253D&md5=69e994e6cc1beb137a0ee7c13869b632
  10. 10
    Mališ, J.; Mazúr, P.; Paidar, M.; Bystron, T.; Bouzek, K. Nafion 117 stability under conditions of PEM water electrolysis at elevated temperature and pressure. Int. J. Hydrogen Energy 2016, 41, 2177– 2188,  DOI: 10.1016/j.ijhydene.2015.11.102
    Google Scholar
    10
    Nafion 117 stability under conditions of PEM water electrolysis at elevated temperature and pressure
    Malis, Jakub; Mazur, Petr; Paidar, Martin; Bystron, Tomas; Bouzek, Karel
    International Journal of Hydrogen Energy (2016), 41 (4), 2177-2188CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)
    In this work a systematic study of the behavior of a Nafion 117 membrane under conditions of elevated temps. (up to 150 °C) and pressure (up to 0.7 MPa) was carried out. Attention focused primarily on the ionic cond. of the membrane in the proton form with exposure to the conditions under study for up to 800 h. The ion-exchange capacity, morphol., FTIR and NMR spectra of the membrane were detd. to explain the decline in cond. obsd. over time. The techniques used did not reveal any chem. degrdn. of the membrane polymer. The morphol. changes to the membrane connected with excessive expansion of the internal structure of the polymer are assumed to be the reason for the phenomenon obsd. Finally, to confirm the conclusions derived, the membrane behavior in a lab.-scale water electrolysis cell was studied under operating conditions corresponding to its prior characterization.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVSgsLfK&md5=b18c650b824bda77551b14416ad179b7
  11. 11
    Brodt, M.; Müller, K.; Kerres, J.; Katsounaros, I.; Mayrhofer, K.; Preuster, P.; Wasserscheid, P.; Thiele, S. The 2-Propanol Fuel Cell: A Review from the Perspective of a Hydrogen Energy Economy. Energy Tech 2021, 9, 2100164,  DOI: 10.1002/ente.202100164
    Google Scholar
    11
    The 2-Propanol Fuel Cell: A Review from the Perspective of a Hydrogen Energy Economy
    Brodt, Matthew; Mueller, Karsten; Kerres, Jochen; Katsounaros, Ioannis; Mayrhofer, Karl; Preuster, Patrick; Wasserscheid, Peter; Thiele, Simon
    Energy Technology (Weinheim, Germany) (2021), 9 (9), 2100164CODEN: ETNEFN; ISSN:2194-4296. (Wiley-VCH Verlag GmbH & Co. KGaA)
    A review The 2-propanol fuel cell has been shown to hold several key advantages over the more established methanol fuel cell, including a comparably high real open-circuit voltage, reduced fuel crossover through a Nafion membrane and a benign toxicol. fuel profile. In addn., while the highly selective partial oxidn. of 2-propanol to acetone in a fuel cell (rather than the more typical complete combustion of org. fuels to CO2) has been viewed as a disadvantage in the past, recent work has shown that the 2-propanol/acetone couple is compatible with traditional hydrocarbon liq. org. hydrogen carrier (LOHC) systems though transfer hydrogenation. With this approach, a disadvantage of hydrogen LOHC logistics-the steep energy cost of dehydrogenation that must be provided during energy-lean times-can be largely avoided. This LOHC compatibility along with the potential for high fuel-cell performance could place the 2-propanol fuel cell (also referred to as the direct isopropanol fuel cell or DIFC) in a position to enable a hydrogen energy economy while avoiding the drawbacks of mol. hydrogen transport and storage. In this Review, the purpose is to ascertain the state-of-the-art of DIFCs-an understudied yet promising research area with unique advantages and challenges.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFOnt7fL&md5=3f56c395570c54ccb2ed7aee86ab55e9
  12. 12
    Mauritz, K. A.; Moore, R. B. State of understanding of nafion. Chemical Reviews 2004, 104, 4535– 4585,  DOI: 10.1021/cr0207123
    Google Scholar
    12
    State of understanding of Nafion
    Mauritz, Kenneth A.; Moore, Robert B.
    Chemical Reviews (Washington, DC, United States) (2004), 104 (10), 4535-4585CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review on morphol. characterization using X-rays and neutrons, microscopy studies, mech. properties, mol. simulations, and the nature of aq. and nonaq. solvents and ions in Nafions.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXns12rtrg%253D&md5=50ff5d518145caaaf7565ac8c62c256f
  13. 13
    Roche, E. J.; Pineri, M.; Duplessix, R.; Levelut, A. M. Small-angle scattering studies of nafion membranes. J. Polym. Sci. Polym. Phys. Ed. 1981, 19, 1– 11,  DOI: 10.1002/pol.1981.180190101
    Google Scholar
    13
    Small-angle scattering studies of Nafion membranes
    Roche, E. J.; Pineri, M.; Duplessix, R.; Levelut, A. M.
    Journal of Polymer Science, Polymer Physics Edition (1981), 19 (1), 1-11CODEN: JPLPAY; ISSN:0098-1273.
    The phys. structure of Nafion [31175-20-9] sulfonic fluoropolymer membranes was studied by small-angle neutron scattering (SANS) and small-angle x-ray scattering (SAXS). Samples in the acid form exhibit 2 scattering peaks. The 1st peak, obsd. by SANS at an angle corresponding to a Bragg spacing of 180 Å, arises from structures in cryst. regions; a second, at larger scattering angles, arises from ion-contg. regions which may be swollen with water. Salt-form samples made by soaking the acid form in aq. salt soln. can also exhibit the same 2 scattering signals. However, in amorphous salt-form samples produced by quenching from the melt, the first peak is absent. This permits a more accurate study of the second peak by SAXS, which shows that the second scattering component is present as a max. over a wide range of water content but is absent in a sample dried at 200°. The position of the peak shifts to a lower scattering angle (or larger spacings) at higher water contents. Possible structure models for explaining the max. are discussed. The large majority of the water mols. are phase sepd. as indicated by anal. of the mean-square electron-d. fluctuation.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3MXms1GmsA%253D%253D&md5=a3ec9d8059213c14553b5799104448d1
  14. 14
    Elabd, Y. A.; Napadensky, E.; Walker, C. W.; Winey, K. I. Transport Properties of Sulfonated Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities. Macromolecules 2006, 39, 399– 407,  DOI: 10.1021/ma051958n
    Google Scholar
    14
    Transport Properties of Sulfonated Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities
    Elabd, Yossef A.; Napadensky, Eugene; Walker, Charles W.; Winey, Karen I.
    Macromolecules (2006), 39 (1), 399-407CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    Transport properties of sulfonated poly(styrene-b-isobutylene-b-styrene) (S-SIBS) triblock copolymers were examd. as a function of ion-exchange capacity (IEC), specifically at high IECs (up to ∼2 mequiv/g). The proton cond. of S-SIBS was ∼1 order of magnitude higher than sulfonated polystyrene at similar IECs and 3-fold higher than Nafion 117 at an IEC of 2 mequiv/g. However, all polymers in this study possessed similar selectivities (i.e., proton cond./methanol permeability) regardless of chem. or morphol. Small-angle X-ray scattering reveals a periodic-to-nonperiodic transition in S-SIBS with an anisotropic lamellar morphol. oriented in the plane of the membrane at IECs ranging from 0.5 to 1 mequiv/g and an isotropic cocontinuous morphol. at IECs ranging from 1.1 to 2 mequiv/g. This morphol. transition coincides with a discontinuity in the IEC-dependent transport properties. In addn., S-SIBS transport properties were measured after soln. casting from 15 different solvents at a const. IEC (0.8 mequiv/g). Transport properties varied by almost 3 orders of magnitude when comparing S-SIBS soln. cast from toluene to a toluene/ethanol mixt. X-ray scattering results show morphol. differences with solvent choice. This study demonstrates the significant impact of morphol. on transport properties in ionic block copolymers.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXht1Gktb%252FE&md5=5048790e1994abcfbd3933c7bad5c2cf
  15. 15
    Einsla, M. L.; Kim, Y. S.; Hawley, M.; Lee, H.-S.; McGrath, J. E.; Liu, B.; Guiver, M. D.; Pivovar, B. S. Toward Improved Conductivity of Sulfonated Aromatic Proton Exchange Membranes at Low Relative Humidity. Chem. Mater. 2008, 20, 5636– 5642,  DOI: 10.1021/cm801198d
    Google Scholar
    15
    Toward Improved Conductivity of Sulfonated Aromatic Proton Exchange Membranes at Low Relative Humidity
    Einsla, Melinda L.; Kim, Yu Seung; Hawley, Marilyn; Lee, Hae-Seung; McGrath, James E.; Liu, Baijun; Guiver, Michael D.; Pivovar, Bryan S.
    Chemistry of Materials (2008), 20 (17), 5636-5642CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)
    Three sulfonated arom. polymers with different sequence lengths were studied to better understand the relation between mol. structure, morphol., and properties of proton exchange membranes as a function of relative humidity. A random copolymer with a statistical distribution of sulfonic acid groups had small domain size, whereas an alternating polymer with sulfonic acid groups spaced evenly along the polymer chain was found to have larger, but quite isolated, domains. The multiblock copolymer studied showed highly phase-sepd. hydrophilic and hydrophobic domains, with good long-range connectivity. Scanning force microscopy as a function of relative humidity was used to observe water absorption and swelling of the hydrophilic domains in each of the three membranes. The cond., water sorption kinetics, and fuel cell performance, esp. at low relative humidity, were highly dependent upon the morphol. The multiblock copolymer outperformed both the random and alternating systems at 100° and 40% RH fuel cell operating conditions and showed similar performance to Nafion.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXpvVaktbg%253D&md5=3cdc8b91685971c75e6dfb348cdc34fc
  16. 16
    Bosson, K.; Marcasuzaa, P.; Bousquet, A.; Tovar, G. E.; Atanasov, V.; Billon, L. PentaFluoroStyrene-based block copolymers controlled self-assembly pattern: A platform paving the way to functional block copolymers. Eur. Polym. J. 2022, 179, 111560,  DOI: 10.1016/j.eurpolymj.2022.111560
    Google Scholar
    16
    PentaFluoroStyrene-based block copolymers controlled self-assembly pattern: A platform paving the way to functional block copolymers
    Bosson, Karell; Marcasuzaa, Pierre; Bousquet, Antoine; Tovar, Gunter E. M.; Atanasov, Vladimir; Billon, Laurent
    European Polymer Journal (2022), 179 (), 111560CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)
    Diblock copolymers of 2,3,4,5,6-pentafluorostyrene (PFS) and Bu acrylate (BuA) were synthesized by nitroxide mediated polymn. (NMP). By varying the conversion and/or the BuA monomer to PPFS macro-initiator ratio, various molar compns. of the block copolymer BCP were obtained. Due to the immiscibility of both polymeric blocks, phase sepn. at the nanometer scale occurred. The variety of BCP synthesized gave rise to a large panel of morphologies by self-assembly. The structuration of the nanodomains of PPFS/PBuA BCPs were studied by AFM and SAXS. Nanodomain sizes ranging from 30 to 45 nm depending on the molar mass of the BCP were obsd. Moreover, the lability of the fluorine atom in para position of the arom. ring of the PFS units allows for the functionalization of the BCPs. Indeed, the para fluorine-thiol soft organo-catalyzed substitution was performed with 1-hexanethiol as side group. The thermal properties and the self-assembly pattern of the BCP changes drastically by the incorporation of alkyl moiety, acting as an artificial increase of the vol. fraction of the PPFS block and also matching the soly. parameter value of the PBA block, i.e. no more nano-pattern is obsd. by AFM and SAXS.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xitl2ksLjJ&md5=ebf1c67d2955991a19e1e1c0c0eeee38
  17. 17
    Bosson, K.; Marcasuzaa, P.; Bousquet, A.; Tovar, G. E.; Atanasov, V.; Billon, L. para fluoro-thiol clicked diblock-copolymer self-assembly: Towards a new paradigm for highly proton-conductive membranes. J. Membr. Sci. 2022, 659, 120796,  DOI: 10.1016/j.memsci.2022.120796
    Google Scholar
    17
    para fluoro-thiol clicked diblock-copolymer self-assembly: Towards a new paradigm for highly proton-conductive membranes
    Bosson, Karell; Marcasuzaa, Pierre; Bousquet, Antoine; Tovar, Gunter E. M.; Atanasov, Vladimir; Billon, Laurent
    Journal of Membrane Science (2022), 659 (), 120796CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
    Sulfonated sPPFS-b-PBuA diblock and statistical copolymers based on 2,3,4,5,6-pentafluorostyrene PFS and Bu acrylate BuA were elaborated for Proton Exchange Membrane Water Electrolyzer (PEMWE) purposes. The block copolymers (BCP) were synthesized by Nitroxide Mediated Polymn. NMP, a controlled radical polymn. technique that yields a well-defined molar mass and a low dispersity material. These diblock-copolymers have the ability to self-assemble due to the immiscibility of the two macromol. segments PPFS and PBuA. Statistical copolymers of the similar chem. compn. were synthesized by both controlled radical polymn. NMP in soln. and by free radical polymn. FRP in emulsion as waterborne dispersed polymer with highest molar mass. The copolymers were sulfonated by a mild click-reaction, namely an organo-catalyzed nucleophilic substitution reaction with sodium 3-mercapto-1-propanesulfonate (SMPS) at low temp. The morphol. of the sulfonated diblock-copolymer BCP was studied by SAXS and AFM, revealing a nano-phase-segregated sulfonated membrane. The mech. properties of the membranes were improved by ionic crosslinking with polybenzimidazole (PBI-OO). Finally, the conductive properties of the sulfonated BCPs and statistical copolymers were investigated as a function of parameters such as the morphol. of the BCP, the molar mass, and the sulfonation degree of the materials.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVaqs77I&md5=0dea39449fea489414dd3c0cccaa300e
  18. 18
    Feng, S.; Voth, G. A. Proton solvation and transport in hydrated nafion. The journal of physical chemistry. B 2011, 115, 5903– 5912,  DOI: 10.1021/jp2002194
    Google Scholar
    18
    Proton Solvation and Transport in Hydrated Nafion
    Feng, Shulu; Voth, Gregory A.
    Journal of Physical Chemistry B (2011), 115 (19), 5903-5912CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
    Proton solvation properties and transport mechanisms have been studied in hydrated Nafion using the self-consistent multistate empirical valence bond (SCI-MS-EVB) method that includes the effects excess proton charge defect delocalization and Grotthuss proton hopping. It was found that sulfonate groups influence excess proton solvation, as well as the proton hydration structure, by stabilizing a more Zundel-like (H5O2+) structure in their first solvation shells. Hydrate proton-related hydrogen bond networks were obsd. to be more stable than networks with water alone. Diffusion rates, Arrhenius activation energies, and transport pathways were calcd. and analyzed to characterize the nature of the proton transport. Diffusion rate anal. suggests that a proton-hopping mechanism dominates the proton transport for the studied water loading levels and that there is a clear degree of anticorrelation with the vehicular transport. The activation energy drops quickly with an increasing water content when the water loading level is smaller than ∼10 H2O/SO3-, which is consistent with exptl. observations. The sulfonate groups were also found to affect the proton hopping directions. The temp. and water content effects on the proton transport pathways were also investigated.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkvFyrsL4%253D&md5=4685ace5a2b09088c1dc9c700842d147
  19. 19
    Lim, K. H.; Lee, A. S.; Atanasov, V.; Kerres, J.; Park, E. J.; Adhikari, S.; Maurya, S.; Manriquez, L. D.; Jung, J.; Fujimoto, C.; Matanovic, I.; Jankovic, J.; Hu, Z.; Jia, H.; Kim, Y. S. Protonated phosphonic acid electrodes for high power heavy-duty vehicle fuel cells. Nat Energy 2022, 7, 248– 259,  DOI: 10.1038/s41560-021-00971-x
    Google Scholar
    19
    Protonated phosphonic acid electrodes for high power heavy-duty vehicle fuel cells
    Lim, Katie H.; Lee, Albert S.; Atanasov, Vladimir; Kerres, Jochen; Park, Eun Joo; Adhikari, Santosh; Maurya, Sandip; Manriquez, Luis Delfin; Jung, Jiyoon; Fujimoto, Cy; Matanovic, Ivana; Jankovic, Jasna; Hu, Zhendong; Jia, Hongfei; Kim, Yu Seung
    Nature Energy (2022), 7 (3), 248-259CODEN: NEANFD; ISSN:2058-7546. (Nature Portfolio)
    State-of-the-art automotive fuel cells that operate at about 80°C require large radiators and air intakes to avoid overheating. High-temp. fuel cells that operate above 100°C under anhyd. conditions provide an ideal soln. for heat rejection in heavy-duty vehicle applications. Here we report protonated phosphonic acid electrodes that remarkably improve the performance of high-temp. polymer electrolyte membrane fuel cells. The protonated phosphonic acids comprise tetrafluorostyrene-phosphonic acid and perfluorosulfonic acid polymers, where a perfluorosulfonic acid proton is transferred to the phosphonic acid to enhance the anhyd. proton conduction of fuel cell electrodes. By using this material in fuel cell electrodes, we obtained a fuel cell exhibiting a rated power d. of 780 mW cm-2 at 160°C, with minimal degrdn. during 2,500 h of operation and 700 thermal cycles from 40 to 160°C under load.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtVWlu78%253D&md5=ff542fb833310343f6976daa07fe1956
  20. 20
    Arslan, F.; Chuluunbandi, K.; Freiberg, A. T. S.; Kormanyos, A.; Sit, F.; Cherevko, S.; Kerres, J.; Thiele, S.; Böhm, T. Performance of Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes in HT-PEMFCs. ACS Applied Materials & Interfaces 2021, 13, 56584– 56596,  DOI: 10.1021/acsami.1c17154
    Google Scholar
    20
    Performance of Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes in HT-PEMFCs
    Arslan, Funda; Chuluunbandi, Khajidkhand; Freiberg, Anna T. S.; Kormanyos, Attila; Sit, Ferit; Cherevko, Serhiy; Kerres, Jochen; Thiele, Simon; Boehm, Thomas
    ACS Applied Materials & Interfaces (2021), 13 (47), 56584-56596CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    High-temp. proton-exchange membrane fuel cells (HT-PEMFCs) are mostly based on acid-doped membranes composed of polybenzimidazole (PBI). A severe drawback of acid-doped membranes is the deterioration of mech. properties upon increasing acid-doping levels. Crosslinking of different polymers is a way to mitigate stability issues. In this study, a new ion-pair-coordinated membrane (IPM) system with quaternary ammonium groups for the application in HT-PEMFCs is introduced. PBI cross-linked with poly(vinylbenzyl chloride) and quaternized with three amines (DABCO, quinuclidine, and quinuclidinol) are manufd. and compared to the state-of-the-art com. Dapazol PBI membrane ex situ as well as by evaluating their HT-PEMFC performance. The IPMs show reduced swelling and better mech. properties upon doping, which enables a redn. in membrane thickness while maintaining a comparably low gas crossover and mech. stability. The HT-PEMFC based on the best-performing IPM reaches up to 530 mW cm-2 at 180°C under H2/air conditions at ambient pressure, while Dapazol is limited to less than 430 mW cm-2 at equal parameters. This new IPM system requires less acid doping than conventional PBI membranes while outperforming conventional PBI membranes, which renders these new membranes promising candidates for application in HT-PEMFCs.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisVyltr7K&md5=41d4c81ad871adddbaca00bf01b0981b
  21. 21
    Pingitore, A. T.; Huang, F.; Qian, G.; Benicewicz, B. C. Durable High Polymer Content m/p -Polybenzimidazole Membranes for Extended Lifetime Electrochemical Devices. ACS Appl. Energy Mater. 2019, 2, 1720– 1726,  DOI: 10.1021/acsaem.8b01820
    Google Scholar
    21
    Durable High Polymer Content m/p-Polybenzimidazole Membranes for Extended Lifetime Electrochemical Devices
    Pingitore, Andrew T.; Huang, Fei; Qian, Guoqing; Benicewicz, Brian C.
    ACS Applied Energy Materials (2019), 2 (3), 1720-1726CODEN: AAEMCQ; ISSN:2574-0962. (American Chemical Society)
    A series of high polymer content phosphoric acid-doped m/p-polybenzimidazole (PBI) copolymer membranes were prepd. via the poly(phosphoric acid) (PPA) process. These copolymer membranes showed much higher soly. in soln. (7-10 wt %) compared to the homopolymer para-PBI (typically <3.5 wt %), which translated to higher polymer solids content in the PPA-processed doped membranes. Concurrent with these changes, the compressive creep compliance (J) decreased from approx. 1 × 10-5 to <2 × 10-6 Pa-1. These membranes exhibited high proton conductivities, >150 mS/cm at typical operating temps. of 160-200 °C, and showed exceptional low voltage decay, ∼0.67 μV/h when tested at 160 °C for more than 2 years.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisF2htbk%253D&md5=2b405528e93cf54db29041ff4c41004c
  22. 22
    Kaserer, S.; Caldwell, K. M.; Ramaker, D. E.; Roth, C. Analyzing the Influence of H3PO4 as Catalyst Poison in High Temperature PEM Fuel Cells Using in-operando X-ray Absorption Spectroscopy. J. Phys. Chem. C 2013, 117, 6210– 6217,  DOI: 10.1021/jp311924q
    Google Scholar
    22
    Analyzing the Influence of H3PO4 as Catalyst Poison in High Temperature PEM Fuel Cells Using in-operando X-ray Absorption Spectroscopy
    Kaserer, Sebastian; Caldwell, Keegan M.; Ramaker, David E.; Roth, Christina
    Journal of Physical Chemistry C (2013), 117 (12), 6210-6217CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    The effect of H3PO4 as a poison in high temp. polymer electrolyte fuel cells using polybenzimidazole (PBI) membranes was studied as a function of H3PO4 loading, potential, and temp. For the 1st time, extensive in-operando x-ray absorption spectroscopy studies were carried out on Pt/C fuel cell cathode catalysts at different temps. and H3PO4 concns. at varying fuel cell voltages. Under in-operando conditions, significant H3PO4 anion coverage of the Pt nanoparticles is obsd. The Δμ-XANES anal. shows that the O(H)/H adsorption onset potential increases/decreases with temp. and that this is a result of phosphate anions being driven off the surface at high temps. (170°). With initial coadsorption of H and O(H), the phosphate anions move into registry with the Pt, whereas random adsorption is obsd. when only phosphate anions are present on the Pt surface. By varying the temp. and the fuel cell potential, the adsorption geometry of the H3PO4 anion changes with coverage, but in all cases, the anions block Pt sites and reduce the O redn. reaction (ORR) rate.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1WmtLg%253D&md5=f1c6fa2787a844740bd02a897f407e0b
  23. 23
    Tang, H.; Gao, J.; Wang, Y.; Li, N.; Geng, K. Phosphoric-Acid Retention in High-Temperature Proton-Exchange Membranes. Chemistry (Weinheim an der Bergstrasse, Germany) 2022, 28, e202202064,  DOI: 10.1002/chem.202202064
    Google Scholar
    There is no corresponding record for this reference.
  24. 24
    Lim, K. H.; Matanovic, I.; Maurya, S.; Kim, Y.; Castro, E. S. de; Jang, J.-H.; Park, H.; Kim, Y. S. High Temperature Polymer Electrolyte Membrane Fuel Cells with High Phosphoric Acid Retention. ACS Energy Lett. 2023, 8, 529– 536,  DOI: 10.1021/acsenergylett.2c02367
    Google Scholar
    24
    High Temperature Polymer Electrolyte Membrane Fuel Cells with High Phosphoric Acid Retention
    Lim, Katie H.; Matanovic, Ivana; Maurya, Sandip; Kim, Youngkwang; De Castro, Emory S.; Jang, Ji-Hoon; Park, Hyounmyung; Kim, Yu Seung
    ACS Energy Letters (2023), 8 (1), 529-536CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society)
    Phosphoric acid loss poses immense hurdles for the durability of high-temp. polymer electrolyte membrane fuel cells (HT-PEMFCs). Here we report quaternary ammonium-biphosphate ion-pair HT-PEMFCs that do not lose phosphoric acids under normal and accelerated stress conditions. Our energetics study explains the acid loss behavior of the conventional phosphoric acid-polybenzimidazole (PA-PBI) system by two mechanisms. If PA loss occurs via acid evapn., the acid loss is const. over time. On the other hand, when water activity in the PA-PBI system is high, exponential decay of PA loss occurs via the water replacement mechanism. Combined 31P NMR and computational studies show that the proposed ion-pair system has six times higher interaction energy, which allows for contg. all PAs in the membrane electrode assemblies under a broad range of operating conditions. In addn., polar interactions between the phosphonic acid ionomer and phosphoric acid explain acid retention in the electrodes of the ion-pair HT-PEMFCs.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtFShtLzM&md5=bb74671c6d567697cfa10c4f7df99e6b
  25. 25
    Atanasov, V.; Kerres, J. Highly Phosphonated Polypentafluorostyrene. Macromolecules 2011, 44, 6416– 6423,  DOI: 10.1021/ma2011574
    Google Scholar
    25
    Highly Phosphonated Polypentafluorostyrene
    Atanasov, Vladimir; Kerres, Jochen
    Macromolecules (Washington, DC, United States) (2011), 44 (16), 6416-6423CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    The synthesis and cond. of highly phosphonated polypentafluorostyrene are demonstrated. Efficient postphosphonation (90%) was achieved via the classical nucleophilic arom. substitution (SNAr) Michaelis-Arbuzov reaction of polypentafluorostyrene (PFS) with tris(trimethylsilyl) phosphite. The contrivance is in the cumulative electron-withdrawing effect of the fluorine functions. This simultaneously facilitates the SNAr reaction and enhances acidity of the resulting phosphonic acid. The most important consequence is a substantial increase of the H+ cond. being the highest one measured on phosphonated polymer: σ = 0.1 S cm-1 at 108 °C, p = 105 Pa water vapor pressure. This value is 4 times higher than the one for poly(vinylphosphonic acid) (σ = 0.025 S cm-1) and higher than Nafion 117 (σ = 0.075 S cm-1) under the same conditions. Addnl., this polymer showed outstanding resistance to oxidative and thermal treatment (Tdecomp = 340 °C at 70% O2 atmosphere). All this makes the phosphonated PFS a very promising candidate as polymer electrolyte for fuel cell applications.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXpsVOgtrc%253D&md5=be826233ed16b28fa7ee2c3d3d2767f5
  26. 26
    Nederstedt, H.; Jannasch, P. Poly(p-terphenyl alkylene)s grafted with highly acidic sulfonated polypentafluorostyrene side chains for proton exchange membranes. J. Membr. Sci. 2022, 647, 120270,  DOI: 10.1016/j.memsci.2022.120270
    Google Scholar
    26
    Poly(p-terphenyl alkylene)s grafted with highly acidic sulfonated polypentafluorostyrene side chains for proton exchange membranes
    Nederstedt, Hannes; Jannasch, Patric
    Journal of Membrane Science (2022), 647 (), 120270CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
    Molecularly well-designed proton exchange membranes (PEMs) with a high local concn. of strongly acidic groups have the potential to fulfill the strict requirements for fuel cell operation under high temp. and low humidity. Here, we have prepd. a series of well-defined and tunable PEMs based on poly(p-phenylene alkylene) backbones functionalized with sulfonated polypentafluorostyrene grafts having different ionic content, degree of grafting and molar mass. First, backbone copolymers were prepd. by superacid-mediated polyhydroxyalkylations of p-terphenyl, 2,2,2-trifluoroacetophenone and 3-bromo-1,1,1-trifluoroacetone. Next, the bromomethyl groups of these copolymers were utilized as initiator sites for atom transfer radical polymn. (ATRP) of pentafluorostyrene. Finally, the polypentafluorostyrene grafts were quant. and selectively sulfonated to introduce highly acidic perfluorophenylsulfonic acid groups. Solvent cast PEMs displayed a microphase sepd. morphol. with domains on the nanoscale, which gave a controlled water uptake that increased only very little between 20 and 80°C. Under fully hydrated conditions, the PEMs reached a max. proton cond. of 154 mS cm-1, exceeding that of Nafion NR212. Under reduced humidity, the cond. was just slightly below that of NR212. In conclusion, the combination of ether-free stiff polymer backbones and the strongly acidic side chains gave rise to nanostructured PEMs with restricted water uptake, high proton cond., stability and robust mech. properties, which merit further investigations of their performance in fuel cells.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhslelsbs%253D&md5=b508402059eb110e69d91fa0bb560fde
  27. 27
    Shao, Z.; Sannigrahi, A.; Jannasch, P. Poly(tetrafluorostyrenephosphonic acid)-polysulfone block copolymers and membranes. J. Polym. Sci. A Polym. Chem. 2013, 51, 4657– 4666,  DOI: 10.1002/pola.26887
    Google Scholar
    27
    Poly(tetrafluorostyrenephosphonic acid)-polysulfone block copolymers and membranes
    Shao, Zhecheng; Sannigrahi, Arindam; Jannasch, Patric
    Journal of Polymer Science, Part A: Polymer Chemistry (2013), 51 (21), 4657-4666CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)
    A series of ionic ABA triblock copolymers having a central polysulfone (PSU) block and poly(2,3,5,6,-tetrafluorostyrene-4-phosphonic acid) (PTFSPA) outer blocks with different lengths were prepd. and studied as electrolyte membranes. PSU with terminal benzyl bromide was used as a bifunctional macroinitiator for the formation of poly(2,3,4,5,6-pentafluorostyrene) (PPFS) blocks by atom transfer radical polymn. Selective and complete phosphonation of the PPFS blocks was achieved via a Michaelis-Arbuzov reaction using tris(trimethylsilyl)phosphite at 170 °C. Copolymer films were cast from soln. and subsequently fully hydrolyzed to produce transparent flexible proton conducting PTFSPA-b-PSU-b-PTFSPA membranes with a thermal stability reaching above 270 °C under air, and increasing with the PTFSPA content. Studies of thin copolymer electrolyte membranes by tapping mode at. force microscopy showed phase sepd. morphologies with continuous proton conducting PTFSPA nano scale domains. Block copolymer membranes reached a proton cond. of 0.08 S cm-1 at 120 °C under fully hydrated conditions, and 0.8 mS cm-1 under 50% relative humidity at 80 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1OqurbO&md5=0cb87db5e12b71a8ffde406ee074bd81
  28. 28
    Yu, L.; Yue, B.; Yan, L.; Zhao, H.; Zhang, J. Proton conducting composite membranes based on sulfonated polysulfone and polysulfone-g-(phosphonated polystyrene) via controlled atom-transfer radical polymerization for fuel cell applications. Solid State Ionics 2019, 338, 103– 112,  DOI: 10.1016/j.ssi.2019.05.012
    Google Scholar
    28
    Proton conducting composite membranes based on sulfonated polysulfone and polysulfone-g-(phosphonated polystyrene) via controlled atom-transfer radical polymerization for fuel cell applications
    Yu, Lesi; Yue, Baohua; Yan, Liuming; Zhao, Hongbin; Zhang, Jiujun
    Solid State Ionics (2019), 338 (), 103-112CODEN: SSIOD3; ISSN:0167-2738. (Elsevier B.V.)
    Polysulfone-g-(phosphonated polystyrene) (PPSF) is synthesized by grafting of poly(phosphonated polystyrene) to polysulfone (PSF) backbone via controlled atom-transfer radical polymn. (ATRP). And its comprehensive performances are improved by compositing with sulfonated polysulfone (SPSF). The best comprehensive performances are achieved in the composite membrane consisting of 80 wt% PPSF and 20 wt% SPSF (P80S20). The max. proton cond. reaches 17.23 mS cm-1 at 95°C and 90% RH, which is 3.3 times as high as the pristine PPSF at 5.22 mS cm-1. In addn., the composite membrane exhibits favorable thermal stability, compromised water uptake and swelling ratio, significantly improved mech. strength. Moreover, the methanol permeability is reduced from 5.74 x 10-8 cm2 s-1 for PPSF to 0.96 x 10-8 cm2 s-1 for P80S20.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXltlCms7k%253D&md5=0cfa834791ed2c680b65ba091e4a0933
  29. 29
    Atanasov, V.; Gudat, D.; Ruffmann, B.; Kerres, J. Highly phosphonated polypentafluorostyrene: Characterization and blends with polybenzimidazole. Eur. Polym. J. 2013, 49, 3977– 3985,  DOI: 10.1016/j.eurpolymj.2013.09.002
    Google Scholar
    29
    Highly phosphonated polypentafluorostyrene: Characterization and blends with polybenzimidazole
    Atanasov, Vladimir; Gudat, Dietrich; Ruffmann, Bastian; Kerres, Jochen
    European Polymer Journal (2013), 49 (12), 3977-3985CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)
    The authors present results of the cond. and resistance to thermooxidative and condensation reactions of a highly phosphonated poly(pentafluorostyrene) (PWN2010) and of its blends with poly(benzimidazole)s (PBI). This polymer, which combines both: (i) a high degree of phosphonation (above 90%) and (ii) a relatively high acidity (pKa (-PO3H2 ↔ -PO3H-) ∼ 0.5) due to the F neighbors, is designed for low humidity operating fuel cell. This was confirmed by the cond. measurements for PWN2010 reaching σ = 5 × 10-4 S cm-1 at 150° in dry N2 and σ = 1 × 10-3 S cm-1 at 150° (λ = 0.75). Also, this polymer showed only 48% of anhydride formation when annealing it at T = 250° for 5 h and only 2% wt. loss during a 96 h Fenton test. These properties combined with the ability of the PWN2010 to form homogeneous blends with polybenzimidazoles resulting in stable and flexible polymer films, makes PWN2010 a very promising candidate as a polymer electrolyte for intermediate- and high-temp. fuel cell applications.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFCju7vI&md5=317b9403c7ff202d1dd898a289ae6548
  30. 30
    Matsushima, S.; Takano, A.; Takahashi, Y.; Matsushita, Y. Precise synthesis of a series of poly(4-n-alkylstyrene)s and their glass transition temperatures. J. Polym. Sci. Part B: Polym. Phys. 2017, 55, 757– 763,  DOI: 10.1002/polb.24326
    Google Scholar
    30
    Precise synthesis of a series of poly(4-n-alkylstyrene)s and their glass transition temperatures
    Matsushima, Satoru; Takano, Atsushi; Takahashi, Yoshiaki; Matsushita, Yushu
    Journal of Polymer Science, Part B: Polymer Physics (2017), 55 (9), 757-763CODEN: JPBPEM; ISSN:0887-6266. (John Wiley & Sons, Inc.)
    Poly(4-n-alkylstyrene)s with six kinds of n-alkyl groups such as Me, Et, Pr, Bu, hexyl, and octyl groups covering wide mol. wt. range from around 5 k to over 100 k were precisely synthesized by living anionic polymns. It was confirmed that all the polymers obtained have narrow mol. wt. distribution, i.e., Mw/Mn is all less than 1.1, by SEC. Tgs of all the polymers were estd. by DSC measurements and it turned out to be clear that their mol. wt. dependence was well described by the Fox-Flory equations. Furthermore, it is evident that Tg monotonically decreases as a no. of carbon atoms of n-alkyl group is increased, though Tg values are all 20 K or more higher than those reported previously for the same polymer series. This is because backbone mobility increases by introducing longer n-alkyl side groups with high mobility, while Tg difference in between this work and the previous one may due to the exptl. conditions and also to the mol. wt. range adopted. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjslSqsLg%253D&md5=c599766a1f7be914870fd10784351ddd
  31. 31
    Funk, L.; Brehmer, M.; Zentel, R.; Kang, H.; Char, K. Novel Amphiphilic Styrene-Based Block Copolymers for Induced Surface Reconstruction. Macromol. Chem. Phys. 2008, 209, 52– 63,  DOI: 10.1002/macp.200700312
    Google Scholar
    31
    Novel amphiphilic styrene-based block copolymers for induced surface reconstruction
    Funk, Lutz; Brehmer, Martin; Zentel, Rudolf; Kang, Huiman; Char, Kookheon
    Macromolecular Chemistry and Physics (2008), 209 (1), 52-63CODEN: MCHPES; ISSN:1022-1352. (Wiley-VCH Verlag GmbH & Co. KGaA)
    This paper describes the synthesis of amphiphilic block copolymers by living radical polymn. (NMP) of new styrene-like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl- or amino-groups after deprotection) were polymd. in a "protected form" to adjust the soly. of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83° as a result of surface reconstruction. Through side chains of different length and with different functionalities, it was possible to adjust the glass transition temps. to values between -2° to 140° for the hydrophilic blocks and -30° to 100° for the hydrophobic block. The wide range of the glass temps. allowed it to find a block copolymer system with a slow kinetic concerning the surface reconstruction process, so that a mechanistic examn. of the process by AFM was possible. It got, thereby, possible to detect the break-up of the hydrophobic surface lamella and the upfold of the hydrophilic lamella in contact with water.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXovVOgtA%253D%253D&md5=bca6715d01e1db1ccce7d009ddf83983
  32. 32
    Jankova, K.; Hvilsted, S. Preparation of Poly(2,3,4,5,6-pentafluorostyrene) and Block Copolymers with Styrene by ATRP. Macromolecules 2003, 36, 1753– 1758,  DOI: 10.1021/ma021039m
    Google Scholar
    32
    Preparation of Poly(2,3,4,5,6-pentafluorostyrene) and Block Copolymers with Styrene by ATRP
    Jankova, Katja; Hvilsted, Soren
    Macromolecules (2003), 36 (5), 1753-1758CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    Poly(2,3,4,5,6-pentafluorostyrene) can be prepd. in high yield at 110°C under ATRP conditions. The polymn. occurs in a controlled manner since the apparent polymn. rate is first order with respect to monomer conversion. Mol. wt. increases linearly with monomer conversion, and the detd. mol. wts. fit the theor. values with relatively low polydispersities. The Br-terminated PFS prepd. by ATRP can function as a macroinitiator for synthesis of PS contg. block copolymers. FS homo- and block copolymers gain higher thermal stability compared to PS. The Tg values for PFS and FS block copolymers with styrene depend on the mol. wt. up to approx. 16000 where a final value at around 101°C is reached. Although the soly. of FS contg. polymers, esp. the homopolymer, is much lower than that of PS, the materials can still be handled as solns.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXhtFCgtrY%253D&md5=c547ebf7f6d87cb599e1cfc6f99190e1
  33. 33
    Atanasov, V.; Oleynikov, A.; Xia, J.; Lyonnard, S.; Kerres, J. Phosphonic acid functionalized poly(pentafluorostyrene) as polyelectrolyte membrane for fuel cell application. Journal of Power Sources 2017, 343, 364– 372,  DOI: 10.1016/j.jpowsour.2017.01.085
    Google Scholar
    33
    Phosphonic acid functionalized poly(pentafluorostyrene) as polyelectrolyte membrane for fuel cell application
    Atanasov, Vladimir; Oleynikov, Andrey; Xia, Jiabing; Lyonnard, Sandrine; Kerres, Jochen
    Journal of Power Sources (2017), 343 (), 364-372CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)
    In this paper we introduce polyelectrolyte membranes based on phosphonated poly(pentafluorostyrene) (PPFS) and their performances in a fuel cell. The polyelectrolytes were obtained via partial phosphonation of PPFS varying the phosphonation degree from 17 to 66%. These membranes showed a high resistance to temp. (Tdecomp. = 355-381°C) and radical attack (96-288 h in Fenton's test). A blend membrane consisting of 82 wt% fully phosphonated PPFS and 18 wt% poly(benzimidazole) is compared to the 66% phosphonated membrane having similar ion-cond. (σ = 57 mS cm-1 at 120 °C, 90% RH). In the fuel cell the blend showed the best performance reaching 0.40 W cm-2 against 0.34 W cm-2 for the 42 wt% phosphonated membrane and 0.35 W cm-2 for Nafion 212. Furthermore, the blend maintained its operation at potentiostatic regime (0.5 V) for 620 h without declining in its performance. The highest power d. of 0.78 W cm-2 was reached for the blend with a thickness of 15 μm using humidified oxygen (RH > 90%) at the cathode side. The switch from humidified to dry gasses during operation reduced the c.d. down to 0.6 A cm-2, but the cell maintained under operation for 66 h.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFens7c%253D&md5=697d47ace0eb1f0745299a78de012c69
  34. 34
    Sun, X.; Guan, J.; Wang, X.; Li, X.; Zheng, J.; Li, S.; Zhang, S. Phosphonated Ionomers of Intrinsic Microporosity with Partially Ordered Structure for High-Temperature Proton Exchange Membrane Fuel Cells. ACS Central Science 2023, 9, 733– 741,  DOI: 10.1021/acscentsci.3c00146
    Google Scholar
    34
    Phosphonated ionomers of intrinsic microporosity with partially ordered structure for high-temperature proton exchange membrane fuel cells
    Sun, Xi; Guan, Jiayu; Wang, Xue; Li, Xiaofeng; Zheng, Jifu; Li, Shenghai; Zhang, Suobo
    ACS Central Science (2023), 9 (4), 733-741CODEN: ACSCII; ISSN:2374-7951. (American Chemical Society)
    High mass transport resistance within the catalyst layer is one of the major factors restricting the performance and low Pt loadings of proton exchange membrane fuel cells (PEMFCs). To resolve the issue, a novel partially ordered phosphonated ionomer (PIM-P) with both an intrinsic microporous structure and proton-conductive functionality was designed as the catalyst binder to improve the mass transport of electrodes. The rigid and contorted structure of PIM-P limits the free movement of the conformation and the efficient packing of polymer chains, resulting in the formation of a robust gas transmission channel. The phosphonated groups provide sites for stable proton conduction. In particular, by incorporating fluorinated and phosphonated groups strategically on the local side chains, an orderly stacking of mol. chains based on group assembly contributes to the construction of efficient mass transport pathways. The peak power d. of the membrane electrode assembly with the PIM-P ionomer is 18-379% greater than that of those with com. or porous catalyst binders at 160°C under an H2/O2 condition. This study emphasizes the crucial role of ordered structure in the rapid conduction of polymers with intrinsic microporosity and provides a new idea for increasing mass transport at electrodes from the perspective of structural design instead of complex processes.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXltF2it7s%253D&md5=b8a5e533974b4096732a0f5320519790
  35. 35
    Vilčiauskas, L.; Tuckerman, M. E.; Bester, G.; Paddison, S. J.; Kreuer, K.-D. The mechanism of proton conduction in phosphoric acid. Nature Chem 2012, 4, 461– 466,  DOI: 10.1038/nchem.1329
    Google Scholar
    35
    The mechanism of proton conduction in phosphoric acid
    Vilciauskas, Linas; Tuckerman, Mark E.; Bester, Gabriel; Paddison, Stephen J.; Kreuer, Klaus-Dieter
    Nature Chemistry (2012), 4 (6), 461-466CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
    Neat liq. H3PO4 has the highest intrinsic proton cond. of any known substance and is a useful model for understanding proton transport in other phosphate-based systems in biol. and clean energy technologies. Here, the authors present an ab initio mol. dynamics study that reveals, for the 1st time, the microscopic mechanism of this high proton cond. Anomalously fast proton transport in H-bonded systems involves a structural diffusion mechanism in which intramol. proton transfer is driven by specific H bond rearrangements in the surrounding environment. Aq. media transport excess charge defects through local H bond rearrangements that drive individual proton transfer reactions. But strong, polarizable H bonds in H3PO4 produce coupled proton motion and a pronounced protic dielec. response of the medium, giving extended, polarized H-bonded chains. The interplay between these chains and a frustrated H-bond network gives rise to the high proton cond.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XlvVKmt7o%253D&md5=1a33fce24b92b02a36a2442b2690128d
  36. 36
    Atanasov, V.; Bürger, M.; Lyonnard, S.; Porcar, L.; Kerres, J. Sulfonated poly(pentafluorostyrene): Synthesis & characterization. Solid State Ionics 2013, 252, 75– 83,  DOI: 10.1016/j.ssi.2013.06.010
    Google Scholar
    36
    Sulfonated poly(pentafluorostyrene): Synthesis & characterization
    Atanasov, Vladimir; Buerger, Matthias; Lyonnard, Sandrine; Porcar, Lionel; Kerres, Jochen
    Solid State Ionics (2013), 252 (), 75-83CODEN: SSIOD3; ISSN:0167-2738. (Elsevier B.V.)
    Prepn. of a high mol. wt. polypentafluorostyrene (PFS) and sulfonated polypentafluorostyrene (sPFS) is described in this paper. The high mol. wt. PFS was obtained via classical emulsion polymn. reaction, which increased the mol. wt. of PFS of about one order of magnitude higher than the one of the com. polymer. The mol. wt. is a crucial factor for the film forming properties of a polymer membrane, following the concept the higher-the better. Furthermore, we post-sulfonated the PFS by 100% (one sulfonic acid per styrene unit). This provided a polymer possessing very high ion-exchange capacity (IEC = 3.4 mmol g-1) with functional group coupled to the relatively flexible side units (Ph rings). The Ph rings are fluorinated which enhanced the nucleophilic substitution reaction (introduction of the functional groups) and reduced the pKa value of the resulting sulfonic acid (pKa = - 2). The morphol. of sPFS, studied by SANS and SAXS, revealed a high ordering of a nano-phase-sepd. system. All these factors raised the cond. to one of the highest measured on polyelectrolyte (σ = 36 mS cm-1 at T = 160 °C, p(H2O) = 105 Pa). This value is one order of magnitude higher than the cond. of Nafion 117 measured under the same conditions.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1Shs7rI&md5=2c27f5b3fdb625ac7a3164b56d609f2a
  37. 37
    Atanasov, V.; Lee, A. S.; Park, E. J.; Maurya, S.; Baca, E. D.; Fujimoto, C.; Hibbs, M.; Matanovic, I.; Kerres, J.; Kim, Y. S. Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells. Nat. Mater. 2021, 20, 370– 377,  DOI: 10.1038/s41563-020-00841-z
    Google Scholar
    37
    Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells
    Atanasov, Vladimir; Lee, Albert S.; Park, Eun Joo; Maurya, Sandip; Baca, Ehren D.; Fujimoto, Cy; Hibbs, Michael; Matanovic, Ivana; Kerres, Jochen; Kim, Yu Seung
    Nature Materials (2021), 20 (3), 370-377CODEN: NMAACR; ISSN:1476-1122. (Nature Research)
    Modern electrochem. energy conversion devices require more advanced proton conductors for their broad applications. Phosphonated polymers have been proposed as anhyd. proton conductors for fuel cells. However, the anhydride formation of phosphonic acid functional groups lowers proton cond. and this prevents the use of phosphonated polymers in fuel cell applications. Here, we report a poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid) that does not undergo anhydride formation and thus maintains protonic cond. above 200°C. We use the phosphonated polymer in fuel cell electrodes with an ion-pair coordinated membrane in a membrane electrode assembly. This synergistically integrated fuel cell reached peak power densities of 1,130 mW cm-2 at 160°C and 1,740 mW cm-2 at 240°C under H2/O2 conditions, substantially outperforming polybenzimidazole- and metal phosphate-based fuel cells. Our result indicates a pathway towards using phosphonated polymers in high-performance fuel cells under hot and dry operating conditions.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFaiurnJ&md5=6b31b483634e5fc8cfeed4bee5d3043a
  38. 38
    Elabd, Y. A.; Hickner, M. A. Block Copolymers for Fuel Cells. Macromolecules 2011, 44, 1– 11,  DOI: 10.1021/ma101247c
    Google Scholar
    38
    Block Copolymers for Fuel Cells
    Elabd, Yossef A.; Hickner, Michael A.
    Macromolecules (Washington, DC, United States) (2011), 44 (1), 1-11CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    A review. Ion-contg. block copolymers hold promise as next-generation proton exchange membranes in hydrogen and methanol fuel cells. These materials self-assembled ordered nanostructures facilitate proton transport over a wide range of conditions, a requirement for robust fuel cell performance. In this perspective, we present an overview of the morphol. and transport properties of ion-contg. block copolymers that have been studied to gain insight into the fundamental behavior of these materials and, in some cases, are targeted toward applications in fuel cells and other electrochem. devices. We discuss the challenges assocd. with predicting and obtaining well-ordered morphologies in block copolymers with high ion content, particularly those with chemistries that can withstand the chem. and mech. stresses of the fuel cell, such as arom. backbone block copolymers. New opportunities for ion-contg. block copolymers in alk. membrane fuel cells are also reviewed.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsV2lu7bE&md5=78705f4268b9207c8b0f7d6924e969b2
  39. 39
    Bae, B.; Miyatake, K.; Watanabe, M. Synthesis and properties of sulfonated block copolymers having fluorenyl groups for fuel-cell applications. ACS Applied Materials & Interfaces 2009, 1, 1279– 1286,  DOI: 10.1021/am900165w
    Google Scholar
    39
    Synthesis and Properties of Sulfonated Block Copolymers Having Fluorenyl Groups for Fuel-Cell Applications
    Bae, Byungchan; Miyatake, Kenji; Watanabe, Masahiro
    ACS Applied Materials & Interfaces (2009), 1 (6), 1279-1286CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
    A series of sulfonated poly(arylene ether sulfone)s (SPEs) block copolymers contg. fluorenyl groups were synthesized. Bis(4-fluorophenyl)sulfone (FPS) and 2,2-bis(4-hydroxy-3,5-dimethylpheny)propane were used as comonomers for hydrophobic blocks, whereas FPS and 9,9-bis(4-hydroxyphenyl)fluorene were used as hydrophilic blocks. Sulfonation with chlorosulfonic acid gave sulfonated block copolymers with mol. wt. (Mw) higher than 150 kDa. Proton cond. of the SPE block copolymer with the ion exchange capacity (IEC) = 2.20 mequiv/g was 0.14 S/cm [80% relative humidity (RH)] and 0.02 S/cm (40% RH) at 80°, which is higher or comparable to that of a perfluorinated ionomer (Nafion) membrane. The longer hydrophilic and hydrophobic blocks resulted in higher water uptake and higher proton cond. Scanning transmission electron microscopy observation revealed that phase sepn. of the SPE block copolymers was more pronounced than that of the SPE random copolymers. The SPE block copolymer membranes showed higher mech. properties than those of the random ones. With these properties, the SPE block copolymer membranes seem promising for fuel-cell applications.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmslOltrY%253D&md5=23caaf01c4b93022dc05bfaab3edfba3
  40. 40
    Shi, Z.; Holdcroft, S. Synthesis and Proton Conductivity of Partially Sulfonated Poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) Block Copolymers. Macromolecules 2005, 38, 4193– 4201,  DOI: 10.1021/ma0477549
    Google Scholar
    40
    Synthesis and Proton Conductivity of Partially Sulfonated Poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) Block Copolymers
    Shi, Zhiqing; Holdcroft, Steven
    Macromolecules (2005), 38 (10), 4193-4201CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    A series of novel, amphiphilic block copolymers comprising of sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) [P(VDF-co-HFP)-b-SPS] were synthesized. The no.-av. mol. wts. of the fluorous and polystyrene segments were 17 900 and 8100 g/mol, resp. Sulfonation of the polystyrene segment to different extents provided a series of polymers which were cast into films to yield proton exchange membranes with varying ion exchange capacity (IEC). Proton cond. of the membranes increased significantly when the IEC was increased from 0.5 to 1.2 mmol/g. For 0.9-1.2 mmol/g IEC membranes, the cond. was similar to Nafion 117, significantly higher than random copolymers of polystyrene and sulfonated polystyrene, and twice that of nonfluorous block copolymer membranes based on sulfonated poly(styrene-b-[ethylene-co-butylene]-b-styrene) (S-SEBS) and sulfonated hydrogenated poly(butadiene-b-styrene) (S-HPBS) copolymers. TEM revealed a disruption in ordered morphol. with increasing degree of sulfonation. Morphol. structures of membranes having 0.6-1.2 mmol/g IEC comprised of interconnected networks of ion channels, each of 8-15 nm width.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXjt1Smt7k%253D&md5=114ebb2bbd2fd6df8a6955efffd5d15c
  41. 41
    Tsang, E. M. W.; Zhang, Z.; Shi, Z.; Soboleva, T.; Holdcroft, S. Considerations of macromolecular structure in the design of proton conducting polymer membranes: graft versus diblock polyelectrolytes. J. Am. Chem. Soc. 2007, 129, 15106– 15107,  DOI: 10.1021/ja074765j
    Google Scholar
    41
    Considerations of Macromolecular Structure in the Design of Proton Conducting Polymer Membranes: Graft versus Diblock Polyelectrolytes
    Tsang, Emily M. W.; Zhang, Zhaobin; Shi, Zhiqing; Soboleva, Tatyana; Holdcroft, Steven
    Journal of the American Chemical Society (2007), 129 (49), 15106-15107CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    Model fluorous-ionic copolymer systems were synthesized and studied to study the role of polymer architecture on morphol. and properties of solid polymer electrolytes. Two types of compositionally similar but architecturally distinct copolymers were studied: P(VDF-co-CTFE)-g-SPS graft copolymers, comprising a hydrophobic fluorous backbone and sulfonated styrene side chains, and P(VDF-co-HFP)-b-SPS diblock copolymers, comprising a hydrophobic fluorous segment linearly connected to a sulfonated styrenic segment. The macromol. structure plays an important role in detg. membrane morphol. Graft membranes possess a small ionic cluster morphol. while diblock membranes possess a lamellar-like morphol. These morphol. differences affect the threshold of ionic percolation, water sorption, proton mobility and concn., proton cond., and anisotropy of ion conduction.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtlWmu7zI&md5=5dd3e11ab9d42cccba453705d3a15a20
  42. 42
    Fritsch, B.; Wu, M.; Hutzler, A.; Zhou, D.; Spruit, R.; Vogl, L.; Will, J.; Hugo Pérez Garza, H.; März, M.; Jank, M. P. M.; Spiecker, E. Sub-Kelvin thermometry for evaluating the local temperature stability within in situ TEM gas cells. Ultramicroscopy 2022, 235, 113494,  DOI: 10.1016/j.ultramic.2022.113494
    Google Scholar
    42
    Sub-Kelvin thermometry for evaluating the local temperature stability within in situ TEM gas cells
    Fritsch, Birk; Wu, Mingjian; Hutzler, Andreas; Zhou, Dan; Spruit, Ronald; Vogl, Lilian; Will, Johannes; Hugo Perez Garza, H.; Maerz, Martin; Jank, Michael P. M.; Spiecker, Erdmann
    Ultramicroscopy (2022), 235 (), 113494CODEN: ULTRD6; ISSN:0304-3991. (Elsevier B.V.)
    In situ TEM utilizing windowed gas cells is a promising technique for studying catalytic processes, wherein temp. is one of the most important parameters to be controlled. Current gas cells are only capable of temp. measurement on a global (mm) scale, although the local temp. at the spot of observation (μm to nm scale) may significantly differ. Thus, local temp. fluctuations caused by gas flow and heat dissipation dynamics remain undetected when solely relying on the global device feedback. In this study, we overcome this limitation by measuring the specimen temp. in situ utilizing parallel-beam electron diffraction at gold nanoparticles. By combining this technique with an advanced data processing algorithm, we achieve sub-Kelvin precision in both, vacuum as well as gaseous environments. Mitigating charging effects is furthermore shown to minimize systematic errors. By utilizing this method, we characterize the local thermal stability of a state-of-the-art gas cell equipped with heating capability in vacuum and under various gas-flow conditions. Our findings provide crucial ref. for in situ investigations into catalysis.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xls1Kntr0%253D&md5=dd4e110785ab0467fe27599561f9a712

Cited By

Click to copy section linkSection link copied!

This article is cited by 1 publications.

  1. Xiang-Tian Bai, Li-Hui Cao, Fang Zhao, Shu-Hui Li. Arylsulfonate Ionic Hydrogen-Bonded Organic Frameworks Enable Highly Stable and Superprotonic Conductivity for Enhancing Direct Methanol Fuel Cells. ACS Materials Letters 2024, 6 (8) , 3351-3357. https://doi.org/10.1021/acsmaterialslett.4c00953
Download PDF
Go to ACS Materials Letters
Get e-Alerts
Get e-Alerts

ACS Materials Letters

Cite this: ACS Materials Lett. 2023, 5, 8, 2039–2046
Click to copy citationCitation copied!
https://doi.org/10.1021/acsmaterialslett.3c00569
Published June 29, 2023

Copyright © 2023 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Article Views

2007

Altmetric

-

Citations

1
Learn about these metrics

Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.

Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.

The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.

  • Abstract

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 1

    Figure 1. Mesostructure simulations of nanophase separation of POS-b-PWN-66 with block lengths of 100:20 (a), 50:50 (b), and 20:100 (c). The simulated cubes consist of 5543 (a), 7763 (b), 7769 (c) distinct POS-b-PWN-66 chains.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 2

    Figure 2. Stepwise synthesis of POS-PPFS by RAFT-polymerization and partial phosphonation.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 3

    Figure 3. Nanophase separation in POS-b-PWN-60. (a) HAADF-STEM images of the Pb2+ stained membrane cross-section and diffractogram for nanostructure size determination. (b) Mean atomic-bond lengths from SAED. (c) Chemical structure of the polymer from synthesis. (d) Nanophase simulation of POS50-b-PWN-6650 with the same parameters as those in Figure 1. Similar to (a), the dark parts correspond to the nonpolar POS-rich phase. (e) Structure domains highlighted in HAADF image and corresponding EDXS images for fluorine, lead, phosphorus, and carbon.

    High Resolution Image
    Download MS PowerPoint Slide

  • References

    This article references 42 other publications.

    1. 1
      Kerres, J. A. Design Concepts for Aromatic Ionomers and Ionomer Membranes to be Applied to Fuel Cells and Electrolysis. Polymer Reviews 2015, 55, 273– 306,  DOI: 10.1080/15583724.2015.1011754
      1
      Design Concepts for Aromatic Ionomers and Ionomer Membranes to be Applied to Fuel Cells and Electrolysis
      Kerres, Jochen A.
      Polymer Reviews (Philadelphia, PA, United States) (2015), 55 (2), 273-306CODEN: PRPPCY; ISSN:1558-3716. (Taylor & Francis, Inc.)
      In this review the research of the author's group regarding the optimization of the chem. stability and properties of arom. ion-exchange polymers by suitable and systematic synthesis of electron-deficient monomer building blocks and by their (co) polymn. into highly stable arom. ionomers are presented. Moreover, the prepn. of phys. or covalently cross-linked ion-exchange membranes by blending these ionomers with each other and with suitable com. polymers to finally afford ion-exchange membranes with properties tailored for electromembrane applications such as fuel cells, electrolysis, and redox-flow batteries are described.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXotFCgu7o%253D&md5=25f05be9f52e0eae711007e652c1dc51
    2. 2
      Chromik, A.; dos Santos, A. R.; Turek, T.; Kunz, U.; Häring, T.; Kerres, J. Stability of acid-excess acid–base blend membranes in all-vanadium redox-flow batteries. J. Membr. Sci. 2015, 476, 148– 155,  DOI: 10.1016/j.memsci.2014.11.036
      2
      Stability of acid-excess acid-base blend membranes in all-vanadium redox-flow batteries
      Chromik, Andreas; dos Santos, Antonio R.; Turek, Thomas; Kunz, Ulrich; Haering, Thomas; Kerres, Jochen
      Journal of Membrane Science (2015), 476 (), 148-155CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
      In this contribution the performance of 2 acid-base blend membranes in an all-V redox-flow battery (VRFB) is studied. The 1st membrane is a nonfluorinated acid-base blend membrane composed of a sulfonated poly(arylene ether sulfone) and polybenzimidazole PBIOO, the 2nd, partially fluorinated, membrane is composed of a sulfonated polymer from decafluorobiphenyl and bisphenol AF and the polybenzimidazole F6PBI. It turns out from gel permeation chromatog. expts. that the mol. wt. of both membranes degrades in VRFB. However the partially fluorinated membrane (S1B1) is more stable in VRFB, which can be seen in the no. of charge/discharge cycles, while the nonfluorinated membrane S2B2 fails after 137 cycles, the partially fluorinated membrane S1B1 survives 200 cycles. Also, the percentage of residual mol. wt. of the nonfluorinated membrane after failure (after 137 cycles) is 34.0%, and of the partially fluorinated membrane (after 200 cycles) is 58.8%, resp. Both membranes show better peak power densities than a Nafion 117 membrane operated in VRFB under the same conditions. In contrast to Nafion 117 and S2B2, the S1B1 membrane shows stable voltage and energy efficiency within the 1st 60 charge/discharge cycles. Also, the Coulomb efficiency of the S1B1 membrane was higher than that of S2B2 and Nafion 117, resp., being nearly 100%.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVems7zE&md5=3df52265f5f223043dea4cdcca101893
    3. 3
      Park, J. E.; Kim, J.; Han, J.; Kim, K.; Park, S.; Kim, S.; Park, H. S.; Cho, Y.-H.; Lee, J.-C.; Sung, Y.-E. High-performance proton-exchange membrane water electrolysis using a sulfonated poly(arylene ether sulfone) membrane and ionomer. J. Membr. Sci. 2021, 620, 118871,  DOI: 10.1016/j.memsci.2020.118871
      3
      High-performance proton-exchange membrane water electrolysis using a sulfonated poly(arylene ether sulfone) membrane and ionomer
      Park, Ji Eun; Kim, Junghwan; Han, Jusung; Kim, Kihyun; Park, SungBin; Kim, Sungjun; Park, Hyun S.; Cho, Yong-Hun; Lee, Jong-Chan; Sung, Yung-Eun
      Journal of Membrane Science (2021), 620 (), 118871CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
      Sulfonated poly(arylene ether sulfone) with degree of sulfonation of 50 mol.% (SPAES50) was synthesized for the prepn. of a hydrocarbon-based membrane and ionomer, for application to proton-exchange membrane water electrolysis (PEMWE) as an alternative to Nafion. The SPAES50 membrane showing the excellent phys. and electrochem. properties as well as the SPAES50-based ionomer (P50) were prepd. and applied to PEMWE to evaluate its performance. The effects of the membrane thickness and ionomer content were also investigated to realize high-performance SPAES-based PEMWE. The proposed SPAES-based PEMWE showed higher performance than that of com. PEMWE with a Nafion membrane and ionomer. Addnl., this is the best performance reported to date, and it is attributed to the low ohmic resistance caused by the high proton cond. of SPAES50 membrane and the small membrane thickness (20 μm). Therefore, we demonstrate the great potential of SPAES50 as a hydrocarbon-based membrane and ionomer in PEMWE.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXitlWnsLnJ&md5=b6a5ff00056126b2ea3aa1e6026e03ba
    4. 4
      Bernt, M.; Gasteiger, H. A. Influence of Ionomer Content in IrO2/TiO2 Electrodes on PEM Water Electrolyzer Performance. J. Electrochem. Soc. 2016, 163, F3179– F3189,  DOI: 10.1149/2.0231611jes
      4
      Influence of ionomer content in IrO2/TiO2 electrodes on PEM water electrolyzer performance
      Bernt, Maximilian; Gasteiger, Hubert A.
      Journal of the Electrochemical Society (2016), 163 (11), F3179-F3189CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)
      In this study, the effect of ionomer content in IrO2/TiO2 anode electrodes for a proton exchange membrane (PEM) electrolyzer is investigated (Nafion 212 membrane; 2.0 mg Ir cm-2/0.35 mg Pt cm-2 (anode/cathode)) and the contributions of ohmic losses, kinetic losses, proton transport losses in the electrodes, and mass transport losses to the overall cell voltage are analyzed. Electrolysis tests are performed with an inhouse designed high pressure electrolyzer cell at differential pressure up to 30 bar. The best performance is obtained for an ionomer content of 11.6 wt% and a cell voltage of 1.57 V at 1 A cm-2 and less than 2 V at 6 A cm-2 (ambient pressure, 80°). Performance losses at lower ionomer contents are the result of a higher proton conduction resistance. For higher ionomer contents, on the other hand, performance losses can be related to a filling of the electrode void vol. by ionomer, leading to a higher O2 mass transport resistance, an increased electronic contact resistance, and the electronic insulation of parts of the catalyst by ionomer. At high pressure operation, the performance cor. by the shift of the Nernst voltage increases with H2 pressure and a new explanation is proposed for this effect.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXpsleisbw%253D&md5=f7c78ad670ca65d89047bf0cd1d7806d
    5. 5
      Kerres, J. A. Development of ionomer membranes for fuel cells. J. Membr. Sci. 2001, 185, 3– 27,  DOI: 10.1016/S0376-7388(00)00631-1
      5
      Development of ionomer membranes for fuel cells
      Kerres, J. A.
      Journal of Membrane Science (2001), 185 (1), 3-27CODEN: JMESDO; ISSN:0376-7388. (Elsevier Science B.V.)
      A review with 78 refs. of state-of-the-art of membrane development for proton-conductive polymer (composite) membranes for fuel cells. For prepn. of the polymers, processes have been developed for sulfonated arylene main-chain polymers as well as for arylene main-chain polymers contg. basic N-contg. groups, including a lithiation step. Covalently cross-linked polymer membranes have been prepd. by alkylation of the sulfinate groups of sulfinate group-contg. polymers with α,ω-dihalogenoalkanes. The advantage of the covalently cross-linked ionomer membranes was their dimensional stability even at temps. of 80-90°; their main disadvantage is their brittleness when drying out, caused by the inflexible covalent network. Sulfonated and basic N-contg. polymers have been combined to acid-base blends contg. ionic cross-links. The main advantage of this membrane type is its flexibility even when dried out, its good-to-excellent thermal stability, and the numerous possibilities to combine acidic and basic polymers to blend membranes having fine-tuned properties. The main disadvantage of this membrane type is the insufficient dimension stability at temps. greater than 70-90°, caused by breakage of the ionic cross-links. Some of the acid-base blend membranes are applied to H2 membrane fuel cells and to direct methanol fuel cells up to 100°, yielding the result that these membranes show very good perspectives for the membrane fuel cell application.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXjtFCrs74%253D&md5=9605d7a7a1127bdde038c3f1cf0b01b5
    6. 6
      Inaba, M.; Kinumoto, T.; Kiriake, M.; Umebayashi, R.; Tasaka, A.; Ogumi, Z. Gas crossover and membrane degradation in polymer electrolyte fuel cells. Electrochim. Acta 2006, 51, 5746– 5753,  DOI: 10.1016/j.electacta.2006.03.008
      6
      Gas crossover and membrane degradation in polymer electrolyte fuel cells
      Inaba, Minoru; Kinumoto, Taro; Kiriake, Masayuki; Umebayashi, Ryota; Tasaka, Akimasa; Ogumi, Zempachi
      Electrochimica Acta (2006), 51 (26), 5746-5753CODEN: ELCAAV; ISSN:0013-4686. (Elsevier B.V.)
      H crossover measurements and durability tests of a single cell under open-circuit conditions were carried out to study membrane degrdn. in polymer electrolyte fuel cells (PEFCs). The limiting c.d. for H crossover was ∼0.8 mA/cm2 at 80° under atm. pressure - gas crossover increased with an increase in cell temp., humidity and H pressure. Under open-circuit conditions, the perfluorinated ionomer electrolyte membrane deteriorated significantly although no net electrochem. reactions took place at the cathode and anode. The mechanism for membrane degrdn. is discussed in terms of heat generation and H2O2 formation upon gas crossover and the resulting catalytic combustion. The latter is the primary reason through which H2O2 is formed by gas crossover of O and the resulting catalytic combustion at the anode. It was inferred that reactive O radicals (HO· and HO2·) were formed in the presence of minor impurities such as Fe2+ and Cu2+ which can accelerate membrane degrdn.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XotVaqtL0%253D&md5=8ac5ae7ddb0b673ac501fb6ba0c02e00
    7. 7
      Auffarth, S.; Dafinger, W.; Mehler, J.; Ardizzon, V.; Preuster, P.; Wasserscheid, P.; Thiele, S.; Kerres, J. Cross-linked proton-exchange membranes with strongly reduced fuel crossover and increased chemical stability for direct-isopropanol fuel cells. J. Mater. Chem. A 2022, 10, 17208– 17216,  DOI: 10.1039/D2TA03832C
      7
      Cross-linked proton-exchange membranes with strongly reduced fuel crossover and increased chemical stability for direct-isopropanol fuel cells
      Auffarth, Sebastian; Dafinger, Willibald; Mehler, Julia; Ardizzon, Valeria; Preuster, Patrick; Wasserscheid, Peter; Thiele, Simon; Kerres, Jochen
      Journal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (33), 17208-17216CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)
      Isopropanol fuel cells offer an attractive way to provide elec. energy from a liq., easily transportable fuel without producing significant amts. of CO2. The oxidn. product acetone can be easily hydrogenated back to isopropanol to close the storage cycle, thereby avoiding the sophisticated handling of fugitive mol. hydrogen. Until now, direct-isopropanol fuel cells (DIFC) usually rely on various perfluorosulfonic acid ionomers, like Nafion, which are costly and have an unfavorable high fluorine content. Addnl., the dissoln. of Nafion in isopropanol/acetone/water solns. within resp. applications has prevented the long time operation of DIFCs so far. The swelling of those ionomers during operation promotes fuel crossover and reduces the systems overall energy efficiency. This study uses ionic crosslinking of polymer blends to manuf. chem. stable membranes and introduces a new click-like covalent crosslinking strategy for ion exchange polymers. Compared to Nafion XL, the manufd. membranes increase the max. power d. by up to 10%, resist a dissoln. stress test up to 84 w% and reduce the detected isopropanol/acetone crossover up to 75/100% during fuel cell operation. Consequently, the material can be considered a major step toward the tech. implementation of isopropanol fuel cell technologies.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XitVOgsLnF&md5=a871be6d8c634200d64948d8fc828232
    8. 8
      Kreuer, K.-D.; Münchinger, A. Fast and Selective Ionic Transport: From Ion-Conducting Channels to Ion Exchange Membranes for Flow Batteries. Annu. Rev. Mater. Res. 2021, 51, 21– 46,  DOI: 10.1146/annurev-matsci-080619-010139
      8
      Fast and Selective Ionic Transport: From Ion-Conducting Channels to Ion Exchange Membranes for Flow Batteries
      Kreuer, Klaus-Dieter; Muenchinger, Andreas
      Annual Review of Materials Research (2021), 51 (), 21-46CODEN: ARMRCU; ISSN:1531-7331. (Annual Reviews)
      This review discusses selective and fast transport of ionic species (ions and their assocs.) through systems as diverse as ion-conducting transmembrane proteins and ion exchange membranes (IEMs) in aq. environments, with special emphasis on the role of electrostatics, specific chem. interactions, and morphol. (steric effects). Contrary to the current doctrine, we suggest that properly balanced ion-coordinating interactions are more important than steric effects for selective ion transport in biol. systems. Steric effects are more relevant to the selectivity of ionic transport through IEMs. As a general rule, decreased hydration leads to higher selectivity but also to lower transport rate. Near-perfect selectivity is achieved by ion-conducting channels in which unhydrated ions transfer through extremely short hydrophobic passages sepg. aq. environments. In IEMs, ionic species practically keep their hydration shell and their transport is sterically constrained by the width of aq. pathways. We discuss the trade-off between selectivity and transport rates and make suggestions for choosing, optimizing, or developing membranes for technol. applications such as vanadium-redox-flow batteries.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1alu7vE&md5=2d61e67e4ff43304025212e5177e094f
    9. 9
      Banerjee, S.; Curtin, D. E. Nafion® perfluorinated membranes in fuel cells. Journal of Fluorine Chemistry 2004, 125, 1211– 1216,  DOI: 10.1016/j.jfluchem.2004.05.018
      9
      Nafion perfluorinated membranes in fuel cells
      Banerjee, Shoibal; Curtin, Dennis E.
      Journal of Fluorine Chemistry (2004), 125 (8), 1211-1216CODEN: JFLCAR; ISSN:0022-1139. (Elsevier B.V.)
      A review. A no. of technologies have been demonstrated to be feasible for generation of power from fuel cells over the last several years. Proton exchange membranes have emerged as an essential factor in the technol. race. DuPont has supplied Nafion perfluorinated membranes in fuel cells for space travel for more than 35 yr and they have played an integral part in the success of recent work in portable, stationary and transportation applications. The basis for proton exchange membrane fuel cell emergence and DuPont technol. utilization is discussed.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXms1yrt70%253D&md5=69e994e6cc1beb137a0ee7c13869b632
    10. 10
      Mališ, J.; Mazúr, P.; Paidar, M.; Bystron, T.; Bouzek, K. Nafion 117 stability under conditions of PEM water electrolysis at elevated temperature and pressure. Int. J. Hydrogen Energy 2016, 41, 2177– 2188,  DOI: 10.1016/j.ijhydene.2015.11.102
      10
      Nafion 117 stability under conditions of PEM water electrolysis at elevated temperature and pressure
      Malis, Jakub; Mazur, Petr; Paidar, Martin; Bystron, Tomas; Bouzek, Karel
      International Journal of Hydrogen Energy (2016), 41 (4), 2177-2188CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)
      In this work a systematic study of the behavior of a Nafion 117 membrane under conditions of elevated temps. (up to 150 °C) and pressure (up to 0.7 MPa) was carried out. Attention focused primarily on the ionic cond. of the membrane in the proton form with exposure to the conditions under study for up to 800 h. The ion-exchange capacity, morphol., FTIR and NMR spectra of the membrane were detd. to explain the decline in cond. obsd. over time. The techniques used did not reveal any chem. degrdn. of the membrane polymer. The morphol. changes to the membrane connected with excessive expansion of the internal structure of the polymer are assumed to be the reason for the phenomenon obsd. Finally, to confirm the conclusions derived, the membrane behavior in a lab.-scale water electrolysis cell was studied under operating conditions corresponding to its prior characterization.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitVSgsLfK&md5=b18c650b824bda77551b14416ad179b7
    11. 11
      Brodt, M.; Müller, K.; Kerres, J.; Katsounaros, I.; Mayrhofer, K.; Preuster, P.; Wasserscheid, P.; Thiele, S. The 2-Propanol Fuel Cell: A Review from the Perspective of a Hydrogen Energy Economy. Energy Tech 2021, 9, 2100164,  DOI: 10.1002/ente.202100164
      11
      The 2-Propanol Fuel Cell: A Review from the Perspective of a Hydrogen Energy Economy
      Brodt, Matthew; Mueller, Karsten; Kerres, Jochen; Katsounaros, Ioannis; Mayrhofer, Karl; Preuster, Patrick; Wasserscheid, Peter; Thiele, Simon
      Energy Technology (Weinheim, Germany) (2021), 9 (9), 2100164CODEN: ETNEFN; ISSN:2194-4296. (Wiley-VCH Verlag GmbH & Co. KGaA)
      A review The 2-propanol fuel cell has been shown to hold several key advantages over the more established methanol fuel cell, including a comparably high real open-circuit voltage, reduced fuel crossover through a Nafion membrane and a benign toxicol. fuel profile. In addn., while the highly selective partial oxidn. of 2-propanol to acetone in a fuel cell (rather than the more typical complete combustion of org. fuels to CO2) has been viewed as a disadvantage in the past, recent work has shown that the 2-propanol/acetone couple is compatible with traditional hydrocarbon liq. org. hydrogen carrier (LOHC) systems though transfer hydrogenation. With this approach, a disadvantage of hydrogen LOHC logistics-the steep energy cost of dehydrogenation that must be provided during energy-lean times-can be largely avoided. This LOHC compatibility along with the potential for high fuel-cell performance could place the 2-propanol fuel cell (also referred to as the direct isopropanol fuel cell or DIFC) in a position to enable a hydrogen energy economy while avoiding the drawbacks of mol. hydrogen transport and storage. In this Review, the purpose is to ascertain the state-of-the-art of DIFCs-an understudied yet promising research area with unique advantages and challenges.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFOnt7fL&md5=3f56c395570c54ccb2ed7aee86ab55e9
    12. 12
      Mauritz, K. A.; Moore, R. B. State of understanding of nafion. Chemical Reviews 2004, 104, 4535– 4585,  DOI: 10.1021/cr0207123
      12
      State of understanding of Nafion
      Mauritz, Kenneth A.; Moore, Robert B.
      Chemical Reviews (Washington, DC, United States) (2004), 104 (10), 4535-4585CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review on morphol. characterization using X-rays and neutrons, microscopy studies, mech. properties, mol. simulations, and the nature of aq. and nonaq. solvents and ions in Nafions.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXns12rtrg%253D&md5=50ff5d518145caaaf7565ac8c62c256f
    13. 13
      Roche, E. J.; Pineri, M.; Duplessix, R.; Levelut, A. M. Small-angle scattering studies of nafion membranes. J. Polym. Sci. Polym. Phys. Ed. 1981, 19, 1– 11,  DOI: 10.1002/pol.1981.180190101
      13
      Small-angle scattering studies of Nafion membranes
      Roche, E. J.; Pineri, M.; Duplessix, R.; Levelut, A. M.
      Journal of Polymer Science, Polymer Physics Edition (1981), 19 (1), 1-11CODEN: JPLPAY; ISSN:0098-1273.
      The phys. structure of Nafion [31175-20-9] sulfonic fluoropolymer membranes was studied by small-angle neutron scattering (SANS) and small-angle x-ray scattering (SAXS). Samples in the acid form exhibit 2 scattering peaks. The 1st peak, obsd. by SANS at an angle corresponding to a Bragg spacing of 180 Å, arises from structures in cryst. regions; a second, at larger scattering angles, arises from ion-contg. regions which may be swollen with water. Salt-form samples made by soaking the acid form in aq. salt soln. can also exhibit the same 2 scattering signals. However, in amorphous salt-form samples produced by quenching from the melt, the first peak is absent. This permits a more accurate study of the second peak by SAXS, which shows that the second scattering component is present as a max. over a wide range of water content but is absent in a sample dried at 200°. The position of the peak shifts to a lower scattering angle (or larger spacings) at higher water contents. Possible structure models for explaining the max. are discussed. The large majority of the water mols. are phase sepd. as indicated by anal. of the mean-square electron-d. fluctuation.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL3MXms1GmsA%253D%253D&md5=a3ec9d8059213c14553b5799104448d1
    14. 14
      Elabd, Y. A.; Napadensky, E.; Walker, C. W.; Winey, K. I. Transport Properties of Sulfonated Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities. Macromolecules 2006, 39, 399– 407,  DOI: 10.1021/ma051958n
      14
      Transport Properties of Sulfonated Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities
      Elabd, Yossef A.; Napadensky, Eugene; Walker, Charles W.; Winey, Karen I.
      Macromolecules (2006), 39 (1), 399-407CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      Transport properties of sulfonated poly(styrene-b-isobutylene-b-styrene) (S-SIBS) triblock copolymers were examd. as a function of ion-exchange capacity (IEC), specifically at high IECs (up to ∼2 mequiv/g). The proton cond. of S-SIBS was ∼1 order of magnitude higher than sulfonated polystyrene at similar IECs and 3-fold higher than Nafion 117 at an IEC of 2 mequiv/g. However, all polymers in this study possessed similar selectivities (i.e., proton cond./methanol permeability) regardless of chem. or morphol. Small-angle X-ray scattering reveals a periodic-to-nonperiodic transition in S-SIBS with an anisotropic lamellar morphol. oriented in the plane of the membrane at IECs ranging from 0.5 to 1 mequiv/g and an isotropic cocontinuous morphol. at IECs ranging from 1.1 to 2 mequiv/g. This morphol. transition coincides with a discontinuity in the IEC-dependent transport properties. In addn., S-SIBS transport properties were measured after soln. casting from 15 different solvents at a const. IEC (0.8 mequiv/g). Transport properties varied by almost 3 orders of magnitude when comparing S-SIBS soln. cast from toluene to a toluene/ethanol mixt. X-ray scattering results show morphol. differences with solvent choice. This study demonstrates the significant impact of morphol. on transport properties in ionic block copolymers.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXht1Gktb%252FE&md5=5048790e1994abcfbd3933c7bad5c2cf
    15. 15
      Einsla, M. L.; Kim, Y. S.; Hawley, M.; Lee, H.-S.; McGrath, J. E.; Liu, B.; Guiver, M. D.; Pivovar, B. S. Toward Improved Conductivity of Sulfonated Aromatic Proton Exchange Membranes at Low Relative Humidity. Chem. Mater. 2008, 20, 5636– 5642,  DOI: 10.1021/cm801198d
      15
      Toward Improved Conductivity of Sulfonated Aromatic Proton Exchange Membranes at Low Relative Humidity
      Einsla, Melinda L.; Kim, Yu Seung; Hawley, Marilyn; Lee, Hae-Seung; McGrath, James E.; Liu, Baijun; Guiver, Michael D.; Pivovar, Bryan S.
      Chemistry of Materials (2008), 20 (17), 5636-5642CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)
      Three sulfonated arom. polymers with different sequence lengths were studied to better understand the relation between mol. structure, morphol., and properties of proton exchange membranes as a function of relative humidity. A random copolymer with a statistical distribution of sulfonic acid groups had small domain size, whereas an alternating polymer with sulfonic acid groups spaced evenly along the polymer chain was found to have larger, but quite isolated, domains. The multiblock copolymer studied showed highly phase-sepd. hydrophilic and hydrophobic domains, with good long-range connectivity. Scanning force microscopy as a function of relative humidity was used to observe water absorption and swelling of the hydrophilic domains in each of the three membranes. The cond., water sorption kinetics, and fuel cell performance, esp. at low relative humidity, were highly dependent upon the morphol. The multiblock copolymer outperformed both the random and alternating systems at 100° and 40% RH fuel cell operating conditions and showed similar performance to Nafion.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXpvVaktbg%253D&md5=3cdc8b91685971c75e6dfb348cdc34fc
    16. 16
      Bosson, K.; Marcasuzaa, P.; Bousquet, A.; Tovar, G. E.; Atanasov, V.; Billon, L. PentaFluoroStyrene-based block copolymers controlled self-assembly pattern: A platform paving the way to functional block copolymers. Eur. Polym. J. 2022, 179, 111560,  DOI: 10.1016/j.eurpolymj.2022.111560
      16
      PentaFluoroStyrene-based block copolymers controlled self-assembly pattern: A platform paving the way to functional block copolymers
      Bosson, Karell; Marcasuzaa, Pierre; Bousquet, Antoine; Tovar, Gunter E. M.; Atanasov, Vladimir; Billon, Laurent
      European Polymer Journal (2022), 179 (), 111560CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)
      Diblock copolymers of 2,3,4,5,6-pentafluorostyrene (PFS) and Bu acrylate (BuA) were synthesized by nitroxide mediated polymn. (NMP). By varying the conversion and/or the BuA monomer to PPFS macro-initiator ratio, various molar compns. of the block copolymer BCP were obtained. Due to the immiscibility of both polymeric blocks, phase sepn. at the nanometer scale occurred. The variety of BCP synthesized gave rise to a large panel of morphologies by self-assembly. The structuration of the nanodomains of PPFS/PBuA BCPs were studied by AFM and SAXS. Nanodomain sizes ranging from 30 to 45 nm depending on the molar mass of the BCP were obsd. Moreover, the lability of the fluorine atom in para position of the arom. ring of the PFS units allows for the functionalization of the BCPs. Indeed, the para fluorine-thiol soft organo-catalyzed substitution was performed with 1-hexanethiol as side group. The thermal properties and the self-assembly pattern of the BCP changes drastically by the incorporation of alkyl moiety, acting as an artificial increase of the vol. fraction of the PPFS block and also matching the soly. parameter value of the PBA block, i.e. no more nano-pattern is obsd. by AFM and SAXS.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xitl2ksLjJ&md5=ebf1c67d2955991a19e1e1c0c0eeee38
    17. 17
      Bosson, K.; Marcasuzaa, P.; Bousquet, A.; Tovar, G. E.; Atanasov, V.; Billon, L. para fluoro-thiol clicked diblock-copolymer self-assembly: Towards a new paradigm for highly proton-conductive membranes. J. Membr. Sci. 2022, 659, 120796,  DOI: 10.1016/j.memsci.2022.120796
      17
      para fluoro-thiol clicked diblock-copolymer self-assembly: Towards a new paradigm for highly proton-conductive membranes
      Bosson, Karell; Marcasuzaa, Pierre; Bousquet, Antoine; Tovar, Gunter E. M.; Atanasov, Vladimir; Billon, Laurent
      Journal of Membrane Science (2022), 659 (), 120796CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
      Sulfonated sPPFS-b-PBuA diblock and statistical copolymers based on 2,3,4,5,6-pentafluorostyrene PFS and Bu acrylate BuA were elaborated for Proton Exchange Membrane Water Electrolyzer (PEMWE) purposes. The block copolymers (BCP) were synthesized by Nitroxide Mediated Polymn. NMP, a controlled radical polymn. technique that yields a well-defined molar mass and a low dispersity material. These diblock-copolymers have the ability to self-assemble due to the immiscibility of the two macromol. segments PPFS and PBuA. Statistical copolymers of the similar chem. compn. were synthesized by both controlled radical polymn. NMP in soln. and by free radical polymn. FRP in emulsion as waterborne dispersed polymer with highest molar mass. The copolymers were sulfonated by a mild click-reaction, namely an organo-catalyzed nucleophilic substitution reaction with sodium 3-mercapto-1-propanesulfonate (SMPS) at low temp. The morphol. of the sulfonated diblock-copolymer BCP was studied by SAXS and AFM, revealing a nano-phase-segregated sulfonated membrane. The mech. properties of the membranes were improved by ionic crosslinking with polybenzimidazole (PBI-OO). Finally, the conductive properties of the sulfonated BCPs and statistical copolymers were investigated as a function of parameters such as the morphol. of the BCP, the molar mass, and the sulfonation degree of the materials.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVaqs77I&md5=0dea39449fea489414dd3c0cccaa300e
    18. 18
      Feng, S.; Voth, G. A. Proton solvation and transport in hydrated nafion. The journal of physical chemistry. B 2011, 115, 5903– 5912,  DOI: 10.1021/jp2002194
      18
      Proton Solvation and Transport in Hydrated Nafion
      Feng, Shulu; Voth, Gregory A.
      Journal of Physical Chemistry B (2011), 115 (19), 5903-5912CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
      Proton solvation properties and transport mechanisms have been studied in hydrated Nafion using the self-consistent multistate empirical valence bond (SCI-MS-EVB) method that includes the effects excess proton charge defect delocalization and Grotthuss proton hopping. It was found that sulfonate groups influence excess proton solvation, as well as the proton hydration structure, by stabilizing a more Zundel-like (H5O2+) structure in their first solvation shells. Hydrate proton-related hydrogen bond networks were obsd. to be more stable than networks with water alone. Diffusion rates, Arrhenius activation energies, and transport pathways were calcd. and analyzed to characterize the nature of the proton transport. Diffusion rate anal. suggests that a proton-hopping mechanism dominates the proton transport for the studied water loading levels and that there is a clear degree of anticorrelation with the vehicular transport. The activation energy drops quickly with an increasing water content when the water loading level is smaller than ∼10 H2O/SO3-, which is consistent with exptl. observations. The sulfonate groups were also found to affect the proton hopping directions. The temp. and water content effects on the proton transport pathways were also investigated.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkvFyrsL4%253D&md5=4685ace5a2b09088c1dc9c700842d147
    19. 19
      Lim, K. H.; Lee, A. S.; Atanasov, V.; Kerres, J.; Park, E. J.; Adhikari, S.; Maurya, S.; Manriquez, L. D.; Jung, J.; Fujimoto, C.; Matanovic, I.; Jankovic, J.; Hu, Z.; Jia, H.; Kim, Y. S. Protonated phosphonic acid electrodes for high power heavy-duty vehicle fuel cells. Nat Energy 2022, 7, 248– 259,  DOI: 10.1038/s41560-021-00971-x
      19
      Protonated phosphonic acid electrodes for high power heavy-duty vehicle fuel cells
      Lim, Katie H.; Lee, Albert S.; Atanasov, Vladimir; Kerres, Jochen; Park, Eun Joo; Adhikari, Santosh; Maurya, Sandip; Manriquez, Luis Delfin; Jung, Jiyoon; Fujimoto, Cy; Matanovic, Ivana; Jankovic, Jasna; Hu, Zhendong; Jia, Hongfei; Kim, Yu Seung
      Nature Energy (2022), 7 (3), 248-259CODEN: NEANFD; ISSN:2058-7546. (Nature Portfolio)
      State-of-the-art automotive fuel cells that operate at about 80°C require large radiators and air intakes to avoid overheating. High-temp. fuel cells that operate above 100°C under anhyd. conditions provide an ideal soln. for heat rejection in heavy-duty vehicle applications. Here we report protonated phosphonic acid electrodes that remarkably improve the performance of high-temp. polymer electrolyte membrane fuel cells. The protonated phosphonic acids comprise tetrafluorostyrene-phosphonic acid and perfluorosulfonic acid polymers, where a perfluorosulfonic acid proton is transferred to the phosphonic acid to enhance the anhyd. proton conduction of fuel cell electrodes. By using this material in fuel cell electrodes, we obtained a fuel cell exhibiting a rated power d. of 780 mW cm-2 at 160°C, with minimal degrdn. during 2,500 h of operation and 700 thermal cycles from 40 to 160°C under load.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtVWlu78%253D&md5=ff542fb833310343f6976daa07fe1956
    20. 20
      Arslan, F.; Chuluunbandi, K.; Freiberg, A. T. S.; Kormanyos, A.; Sit, F.; Cherevko, S.; Kerres, J.; Thiele, S.; Böhm, T. Performance of Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes in HT-PEMFCs. ACS Applied Materials & Interfaces 2021, 13, 56584– 56596,  DOI: 10.1021/acsami.1c17154
      20
      Performance of Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes in HT-PEMFCs
      Arslan, Funda; Chuluunbandi, Khajidkhand; Freiberg, Anna T. S.; Kormanyos, Attila; Sit, Ferit; Cherevko, Serhiy; Kerres, Jochen; Thiele, Simon; Boehm, Thomas
      ACS Applied Materials & Interfaces (2021), 13 (47), 56584-56596CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      High-temp. proton-exchange membrane fuel cells (HT-PEMFCs) are mostly based on acid-doped membranes composed of polybenzimidazole (PBI). A severe drawback of acid-doped membranes is the deterioration of mech. properties upon increasing acid-doping levels. Crosslinking of different polymers is a way to mitigate stability issues. In this study, a new ion-pair-coordinated membrane (IPM) system with quaternary ammonium groups for the application in HT-PEMFCs is introduced. PBI cross-linked with poly(vinylbenzyl chloride) and quaternized with three amines (DABCO, quinuclidine, and quinuclidinol) are manufd. and compared to the state-of-the-art com. Dapazol PBI membrane ex situ as well as by evaluating their HT-PEMFC performance. The IPMs show reduced swelling and better mech. properties upon doping, which enables a redn. in membrane thickness while maintaining a comparably low gas crossover and mech. stability. The HT-PEMFC based on the best-performing IPM reaches up to 530 mW cm-2 at 180°C under H2/air conditions at ambient pressure, while Dapazol is limited to less than 430 mW cm-2 at equal parameters. This new IPM system requires less acid doping than conventional PBI membranes while outperforming conventional PBI membranes, which renders these new membranes promising candidates for application in HT-PEMFCs.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisVyltr7K&md5=41d4c81ad871adddbaca00bf01b0981b
    21. 21
      Pingitore, A. T.; Huang, F.; Qian, G.; Benicewicz, B. C. Durable High Polymer Content m/p -Polybenzimidazole Membranes for Extended Lifetime Electrochemical Devices. ACS Appl. Energy Mater. 2019, 2, 1720– 1726,  DOI: 10.1021/acsaem.8b01820
      21
      Durable High Polymer Content m/p-Polybenzimidazole Membranes for Extended Lifetime Electrochemical Devices
      Pingitore, Andrew T.; Huang, Fei; Qian, Guoqing; Benicewicz, Brian C.
      ACS Applied Energy Materials (2019), 2 (3), 1720-1726CODEN: AAEMCQ; ISSN:2574-0962. (American Chemical Society)
      A series of high polymer content phosphoric acid-doped m/p-polybenzimidazole (PBI) copolymer membranes were prepd. via the poly(phosphoric acid) (PPA) process. These copolymer membranes showed much higher soly. in soln. (7-10 wt %) compared to the homopolymer para-PBI (typically <3.5 wt %), which translated to higher polymer solids content in the PPA-processed doped membranes. Concurrent with these changes, the compressive creep compliance (J) decreased from approx. 1 × 10-5 to <2 × 10-6 Pa-1. These membranes exhibited high proton conductivities, >150 mS/cm at typical operating temps. of 160-200 °C, and showed exceptional low voltage decay, ∼0.67 μV/h when tested at 160 °C for more than 2 years.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisF2htbk%253D&md5=2b405528e93cf54db29041ff4c41004c
    22. 22
      Kaserer, S.; Caldwell, K. M.; Ramaker, D. E.; Roth, C. Analyzing the Influence of H3PO4 as Catalyst Poison in High Temperature PEM Fuel Cells Using in-operando X-ray Absorption Spectroscopy. J. Phys. Chem. C 2013, 117, 6210– 6217,  DOI: 10.1021/jp311924q
      22
      Analyzing the Influence of H3PO4 as Catalyst Poison in High Temperature PEM Fuel Cells Using in-operando X-ray Absorption Spectroscopy
      Kaserer, Sebastian; Caldwell, Keegan M.; Ramaker, David E.; Roth, Christina
      Journal of Physical Chemistry C (2013), 117 (12), 6210-6217CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      The effect of H3PO4 as a poison in high temp. polymer electrolyte fuel cells using polybenzimidazole (PBI) membranes was studied as a function of H3PO4 loading, potential, and temp. For the 1st time, extensive in-operando x-ray absorption spectroscopy studies were carried out on Pt/C fuel cell cathode catalysts at different temps. and H3PO4 concns. at varying fuel cell voltages. Under in-operando conditions, significant H3PO4 anion coverage of the Pt nanoparticles is obsd. The Δμ-XANES anal. shows that the O(H)/H adsorption onset potential increases/decreases with temp. and that this is a result of phosphate anions being driven off the surface at high temps. (170°). With initial coadsorption of H and O(H), the phosphate anions move into registry with the Pt, whereas random adsorption is obsd. when only phosphate anions are present on the Pt surface. By varying the temp. and the fuel cell potential, the adsorption geometry of the H3PO4 anion changes with coverage, but in all cases, the anions block Pt sites and reduce the O redn. reaction (ORR) rate.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjt1WmtLg%253D&md5=f1c6fa2787a844740bd02a897f407e0b
    23. 23
      Tang, H.; Gao, J.; Wang, Y.; Li, N.; Geng, K. Phosphoric-Acid Retention in High-Temperature Proton-Exchange Membranes. Chemistry (Weinheim an der Bergstrasse, Germany) 2022, 28, e202202064,  DOI: 10.1002/chem.202202064
      There is no corresponding record for this reference.
    24. 24
      Lim, K. H.; Matanovic, I.; Maurya, S.; Kim, Y.; Castro, E. S. de; Jang, J.-H.; Park, H.; Kim, Y. S. High Temperature Polymer Electrolyte Membrane Fuel Cells with High Phosphoric Acid Retention. ACS Energy Lett. 2023, 8, 529– 536,  DOI: 10.1021/acsenergylett.2c02367
      24
      High Temperature Polymer Electrolyte Membrane Fuel Cells with High Phosphoric Acid Retention
      Lim, Katie H.; Matanovic, Ivana; Maurya, Sandip; Kim, Youngkwang; De Castro, Emory S.; Jang, Ji-Hoon; Park, Hyounmyung; Kim, Yu Seung
      ACS Energy Letters (2023), 8 (1), 529-536CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society)
      Phosphoric acid loss poses immense hurdles for the durability of high-temp. polymer electrolyte membrane fuel cells (HT-PEMFCs). Here we report quaternary ammonium-biphosphate ion-pair HT-PEMFCs that do not lose phosphoric acids under normal and accelerated stress conditions. Our energetics study explains the acid loss behavior of the conventional phosphoric acid-polybenzimidazole (PA-PBI) system by two mechanisms. If PA loss occurs via acid evapn., the acid loss is const. over time. On the other hand, when water activity in the PA-PBI system is high, exponential decay of PA loss occurs via the water replacement mechanism. Combined 31P NMR and computational studies show that the proposed ion-pair system has six times higher interaction energy, which allows for contg. all PAs in the membrane electrode assemblies under a broad range of operating conditions. In addn., polar interactions between the phosphonic acid ionomer and phosphoric acid explain acid retention in the electrodes of the ion-pair HT-PEMFCs.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtFShtLzM&md5=bb74671c6d567697cfa10c4f7df99e6b
    25. 25
      Atanasov, V.; Kerres, J. Highly Phosphonated Polypentafluorostyrene. Macromolecules 2011, 44, 6416– 6423,  DOI: 10.1021/ma2011574
      25
      Highly Phosphonated Polypentafluorostyrene
      Atanasov, Vladimir; Kerres, Jochen
      Macromolecules (Washington, DC, United States) (2011), 44 (16), 6416-6423CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      The synthesis and cond. of highly phosphonated polypentafluorostyrene are demonstrated. Efficient postphosphonation (90%) was achieved via the classical nucleophilic arom. substitution (SNAr) Michaelis-Arbuzov reaction of polypentafluorostyrene (PFS) with tris(trimethylsilyl) phosphite. The contrivance is in the cumulative electron-withdrawing effect of the fluorine functions. This simultaneously facilitates the SNAr reaction and enhances acidity of the resulting phosphonic acid. The most important consequence is a substantial increase of the H+ cond. being the highest one measured on phosphonated polymer: σ = 0.1 S cm-1 at 108 °C, p = 105 Pa water vapor pressure. This value is 4 times higher than the one for poly(vinylphosphonic acid) (σ = 0.025 S cm-1) and higher than Nafion 117 (σ = 0.075 S cm-1) under the same conditions. Addnl., this polymer showed outstanding resistance to oxidative and thermal treatment (Tdecomp = 340 °C at 70% O2 atmosphere). All this makes the phosphonated PFS a very promising candidate as polymer electrolyte for fuel cell applications.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXpsVOgtrc%253D&md5=be826233ed16b28fa7ee2c3d3d2767f5
    26. 26
      Nederstedt, H.; Jannasch, P. Poly(p-terphenyl alkylene)s grafted with highly acidic sulfonated polypentafluorostyrene side chains for proton exchange membranes. J. Membr. Sci. 2022, 647, 120270,  DOI: 10.1016/j.memsci.2022.120270
      26
      Poly(p-terphenyl alkylene)s grafted with highly acidic sulfonated polypentafluorostyrene side chains for proton exchange membranes
      Nederstedt, Hannes; Jannasch, Patric
      Journal of Membrane Science (2022), 647 (), 120270CODEN: JMESDO; ISSN:0376-7388. (Elsevier B.V.)
      Molecularly well-designed proton exchange membranes (PEMs) with a high local concn. of strongly acidic groups have the potential to fulfill the strict requirements for fuel cell operation under high temp. and low humidity. Here, we have prepd. a series of well-defined and tunable PEMs based on poly(p-phenylene alkylene) backbones functionalized with sulfonated polypentafluorostyrene grafts having different ionic content, degree of grafting and molar mass. First, backbone copolymers were prepd. by superacid-mediated polyhydroxyalkylations of p-terphenyl, 2,2,2-trifluoroacetophenone and 3-bromo-1,1,1-trifluoroacetone. Next, the bromomethyl groups of these copolymers were utilized as initiator sites for atom transfer radical polymn. (ATRP) of pentafluorostyrene. Finally, the polypentafluorostyrene grafts were quant. and selectively sulfonated to introduce highly acidic perfluorophenylsulfonic acid groups. Solvent cast PEMs displayed a microphase sepd. morphol. with domains on the nanoscale, which gave a controlled water uptake that increased only very little between 20 and 80°C. Under fully hydrated conditions, the PEMs reached a max. proton cond. of 154 mS cm-1, exceeding that of Nafion NR212. Under reduced humidity, the cond. was just slightly below that of NR212. In conclusion, the combination of ether-free stiff polymer backbones and the strongly acidic side chains gave rise to nanostructured PEMs with restricted water uptake, high proton cond., stability and robust mech. properties, which merit further investigations of their performance in fuel cells.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhslelsbs%253D&md5=b508402059eb110e69d91fa0bb560fde
    27. 27
      Shao, Z.; Sannigrahi, A.; Jannasch, P. Poly(tetrafluorostyrenephosphonic acid)-polysulfone block copolymers and membranes. J. Polym. Sci. A Polym. Chem. 2013, 51, 4657– 4666,  DOI: 10.1002/pola.26887
      27
      Poly(tetrafluorostyrenephosphonic acid)-polysulfone block copolymers and membranes
      Shao, Zhecheng; Sannigrahi, Arindam; Jannasch, Patric
      Journal of Polymer Science, Part A: Polymer Chemistry (2013), 51 (21), 4657-4666CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)
      A series of ionic ABA triblock copolymers having a central polysulfone (PSU) block and poly(2,3,5,6,-tetrafluorostyrene-4-phosphonic acid) (PTFSPA) outer blocks with different lengths were prepd. and studied as electrolyte membranes. PSU with terminal benzyl bromide was used as a bifunctional macroinitiator for the formation of poly(2,3,4,5,6-pentafluorostyrene) (PPFS) blocks by atom transfer radical polymn. Selective and complete phosphonation of the PPFS blocks was achieved via a Michaelis-Arbuzov reaction using tris(trimethylsilyl)phosphite at 170 °C. Copolymer films were cast from soln. and subsequently fully hydrolyzed to produce transparent flexible proton conducting PTFSPA-b-PSU-b-PTFSPA membranes with a thermal stability reaching above 270 °C under air, and increasing with the PTFSPA content. Studies of thin copolymer electrolyte membranes by tapping mode at. force microscopy showed phase sepd. morphologies with continuous proton conducting PTFSPA nano scale domains. Block copolymer membranes reached a proton cond. of 0.08 S cm-1 at 120 °C under fully hydrated conditions, and 0.8 mS cm-1 under 50% relative humidity at 80 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1OqurbO&md5=0cb87db5e12b71a8ffde406ee074bd81
    28. 28
      Yu, L.; Yue, B.; Yan, L.; Zhao, H.; Zhang, J. Proton conducting composite membranes based on sulfonated polysulfone and polysulfone-g-(phosphonated polystyrene) via controlled atom-transfer radical polymerization for fuel cell applications. Solid State Ionics 2019, 338, 103– 112,  DOI: 10.1016/j.ssi.2019.05.012
      28
      Proton conducting composite membranes based on sulfonated polysulfone and polysulfone-g-(phosphonated polystyrene) via controlled atom-transfer radical polymerization for fuel cell applications
      Yu, Lesi; Yue, Baohua; Yan, Liuming; Zhao, Hongbin; Zhang, Jiujun
      Solid State Ionics (2019), 338 (), 103-112CODEN: SSIOD3; ISSN:0167-2738. (Elsevier B.V.)
      Polysulfone-g-(phosphonated polystyrene) (PPSF) is synthesized by grafting of poly(phosphonated polystyrene) to polysulfone (PSF) backbone via controlled atom-transfer radical polymn. (ATRP). And its comprehensive performances are improved by compositing with sulfonated polysulfone (SPSF). The best comprehensive performances are achieved in the composite membrane consisting of 80 wt% PPSF and 20 wt% SPSF (P80S20). The max. proton cond. reaches 17.23 mS cm-1 at 95°C and 90% RH, which is 3.3 times as high as the pristine PPSF at 5.22 mS cm-1. In addn., the composite membrane exhibits favorable thermal stability, compromised water uptake and swelling ratio, significantly improved mech. strength. Moreover, the methanol permeability is reduced from 5.74 x 10-8 cm2 s-1 for PPSF to 0.96 x 10-8 cm2 s-1 for P80S20.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXltlCms7k%253D&md5=0cfa834791ed2c680b65ba091e4a0933
    29. 29
      Atanasov, V.; Gudat, D.; Ruffmann, B.; Kerres, J. Highly phosphonated polypentafluorostyrene: Characterization and blends with polybenzimidazole. Eur. Polym. J. 2013, 49, 3977– 3985,  DOI: 10.1016/j.eurpolymj.2013.09.002
      29
      Highly phosphonated polypentafluorostyrene: Characterization and blends with polybenzimidazole
      Atanasov, Vladimir; Gudat, Dietrich; Ruffmann, Bastian; Kerres, Jochen
      European Polymer Journal (2013), 49 (12), 3977-3985CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)
      The authors present results of the cond. and resistance to thermooxidative and condensation reactions of a highly phosphonated poly(pentafluorostyrene) (PWN2010) and of its blends with poly(benzimidazole)s (PBI). This polymer, which combines both: (i) a high degree of phosphonation (above 90%) and (ii) a relatively high acidity (pKa (-PO3H2 ↔ -PO3H-) ∼ 0.5) due to the F neighbors, is designed for low humidity operating fuel cell. This was confirmed by the cond. measurements for PWN2010 reaching σ = 5 × 10-4 S cm-1 at 150° in dry N2 and σ = 1 × 10-3 S cm-1 at 150° (λ = 0.75). Also, this polymer showed only 48% of anhydride formation when annealing it at T = 250° for 5 h and only 2% wt. loss during a 96 h Fenton test. These properties combined with the ability of the PWN2010 to form homogeneous blends with polybenzimidazoles resulting in stable and flexible polymer films, makes PWN2010 a very promising candidate as a polymer electrolyte for intermediate- and high-temp. fuel cell applications.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhsFCju7vI&md5=317b9403c7ff202d1dd898a289ae6548
    30. 30
      Matsushima, S.; Takano, A.; Takahashi, Y.; Matsushita, Y. Precise synthesis of a series of poly(4-n-alkylstyrene)s and their glass transition temperatures. J. Polym. Sci. Part B: Polym. Phys. 2017, 55, 757– 763,  DOI: 10.1002/polb.24326
      30
      Precise synthesis of a series of poly(4-n-alkylstyrene)s and their glass transition temperatures
      Matsushima, Satoru; Takano, Atsushi; Takahashi, Yoshiaki; Matsushita, Yushu
      Journal of Polymer Science, Part B: Polymer Physics (2017), 55 (9), 757-763CODEN: JPBPEM; ISSN:0887-6266. (John Wiley & Sons, Inc.)
      Poly(4-n-alkylstyrene)s with six kinds of n-alkyl groups such as Me, Et, Pr, Bu, hexyl, and octyl groups covering wide mol. wt. range from around 5 k to over 100 k were precisely synthesized by living anionic polymns. It was confirmed that all the polymers obtained have narrow mol. wt. distribution, i.e., Mw/Mn is all less than 1.1, by SEC. Tgs of all the polymers were estd. by DSC measurements and it turned out to be clear that their mol. wt. dependence was well described by the Fox-Flory equations. Furthermore, it is evident that Tg monotonically decreases as a no. of carbon atoms of n-alkyl group is increased, though Tg values are all 20 K or more higher than those reported previously for the same polymer series. This is because backbone mobility increases by introducing longer n-alkyl side groups with high mobility, while Tg difference in between this work and the previous one may due to the exptl. conditions and also to the mol. wt. range adopted. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjslSqsLg%253D&md5=c599766a1f7be914870fd10784351ddd
    31. 31
      Funk, L.; Brehmer, M.; Zentel, R.; Kang, H.; Char, K. Novel Amphiphilic Styrene-Based Block Copolymers for Induced Surface Reconstruction. Macromol. Chem. Phys. 2008, 209, 52– 63,  DOI: 10.1002/macp.200700312
      31
      Novel amphiphilic styrene-based block copolymers for induced surface reconstruction
      Funk, Lutz; Brehmer, Martin; Zentel, Rudolf; Kang, Huiman; Char, Kookheon
      Macromolecular Chemistry and Physics (2008), 209 (1), 52-63CODEN: MCHPES; ISSN:1022-1352. (Wiley-VCH Verlag GmbH & Co. KGaA)
      This paper describes the synthesis of amphiphilic block copolymers by living radical polymn. (NMP) of new styrene-like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl- or amino-groups after deprotection) were polymd. in a "protected form" to adjust the soly. of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83° as a result of surface reconstruction. Through side chains of different length and with different functionalities, it was possible to adjust the glass transition temps. to values between -2° to 140° for the hydrophilic blocks and -30° to 100° for the hydrophobic block. The wide range of the glass temps. allowed it to find a block copolymer system with a slow kinetic concerning the surface reconstruction process, so that a mechanistic examn. of the process by AFM was possible. It got, thereby, possible to detect the break-up of the hydrophobic surface lamella and the upfold of the hydrophilic lamella in contact with water.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXovVOgtA%253D%253D&md5=bca6715d01e1db1ccce7d009ddf83983
    32. 32
      Jankova, K.; Hvilsted, S. Preparation of Poly(2,3,4,5,6-pentafluorostyrene) and Block Copolymers with Styrene by ATRP. Macromolecules 2003, 36, 1753– 1758,  DOI: 10.1021/ma021039m
      32
      Preparation of Poly(2,3,4,5,6-pentafluorostyrene) and Block Copolymers with Styrene by ATRP
      Jankova, Katja; Hvilsted, Soren
      Macromolecules (2003), 36 (5), 1753-1758CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      Poly(2,3,4,5,6-pentafluorostyrene) can be prepd. in high yield at 110°C under ATRP conditions. The polymn. occurs in a controlled manner since the apparent polymn. rate is first order with respect to monomer conversion. Mol. wt. increases linearly with monomer conversion, and the detd. mol. wts. fit the theor. values with relatively low polydispersities. The Br-terminated PFS prepd. by ATRP can function as a macroinitiator for synthesis of PS contg. block copolymers. FS homo- and block copolymers gain higher thermal stability compared to PS. The Tg values for PFS and FS block copolymers with styrene depend on the mol. wt. up to approx. 16000 where a final value at around 101°C is reached. Although the soly. of FS contg. polymers, esp. the homopolymer, is much lower than that of PS, the materials can still be handled as solns.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXhtFCgtrY%253D&md5=c547ebf7f6d87cb599e1cfc6f99190e1
    33. 33
      Atanasov, V.; Oleynikov, A.; Xia, J.; Lyonnard, S.; Kerres, J. Phosphonic acid functionalized poly(pentafluorostyrene) as polyelectrolyte membrane for fuel cell application. Journal of Power Sources 2017, 343, 364– 372,  DOI: 10.1016/j.jpowsour.2017.01.085
      33
      Phosphonic acid functionalized poly(pentafluorostyrene) as polyelectrolyte membrane for fuel cell application
      Atanasov, Vladimir; Oleynikov, Andrey; Xia, Jiabing; Lyonnard, Sandrine; Kerres, Jochen
      Journal of Power Sources (2017), 343 (), 364-372CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)
      In this paper we introduce polyelectrolyte membranes based on phosphonated poly(pentafluorostyrene) (PPFS) and their performances in a fuel cell. The polyelectrolytes were obtained via partial phosphonation of PPFS varying the phosphonation degree from 17 to 66%. These membranes showed a high resistance to temp. (Tdecomp. = 355-381°C) and radical attack (96-288 h in Fenton's test). A blend membrane consisting of 82 wt% fully phosphonated PPFS and 18 wt% poly(benzimidazole) is compared to the 66% phosphonated membrane having similar ion-cond. (σ = 57 mS cm-1 at 120 °C, 90% RH). In the fuel cell the blend showed the best performance reaching 0.40 W cm-2 against 0.34 W cm-2 for the 42 wt% phosphonated membrane and 0.35 W cm-2 for Nafion 212. Furthermore, the blend maintained its operation at potentiostatic regime (0.5 V) for 620 h without declining in its performance. The highest power d. of 0.78 W cm-2 was reached for the blend with a thickness of 15 μm using humidified oxygen (RH > 90%) at the cathode side. The switch from humidified to dry gasses during operation reduced the c.d. down to 0.6 A cm-2, but the cell maintained under operation for 66 h.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFens7c%253D&md5=697d47ace0eb1f0745299a78de012c69
    34. 34
      Sun, X.; Guan, J.; Wang, X.; Li, X.; Zheng, J.; Li, S.; Zhang, S. Phosphonated Ionomers of Intrinsic Microporosity with Partially Ordered Structure for High-Temperature Proton Exchange Membrane Fuel Cells. ACS Central Science 2023, 9, 733– 741,  DOI: 10.1021/acscentsci.3c00146
      34
      Phosphonated ionomers of intrinsic microporosity with partially ordered structure for high-temperature proton exchange membrane fuel cells
      Sun, Xi; Guan, Jiayu; Wang, Xue; Li, Xiaofeng; Zheng, Jifu; Li, Shenghai; Zhang, Suobo
      ACS Central Science (2023), 9 (4), 733-741CODEN: ACSCII; ISSN:2374-7951. (American Chemical Society)
      High mass transport resistance within the catalyst layer is one of the major factors restricting the performance and low Pt loadings of proton exchange membrane fuel cells (PEMFCs). To resolve the issue, a novel partially ordered phosphonated ionomer (PIM-P) with both an intrinsic microporous structure and proton-conductive functionality was designed as the catalyst binder to improve the mass transport of electrodes. The rigid and contorted structure of PIM-P limits the free movement of the conformation and the efficient packing of polymer chains, resulting in the formation of a robust gas transmission channel. The phosphonated groups provide sites for stable proton conduction. In particular, by incorporating fluorinated and phosphonated groups strategically on the local side chains, an orderly stacking of mol. chains based on group assembly contributes to the construction of efficient mass transport pathways. The peak power d. of the membrane electrode assembly with the PIM-P ionomer is 18-379% greater than that of those with com. or porous catalyst binders at 160°C under an H2/O2 condition. This study emphasizes the crucial role of ordered structure in the rapid conduction of polymers with intrinsic microporosity and provides a new idea for increasing mass transport at electrodes from the perspective of structural design instead of complex processes.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXltF2it7s%253D&md5=b8a5e533974b4096732a0f5320519790
    35. 35
      Vilčiauskas, L.; Tuckerman, M. E.; Bester, G.; Paddison, S. J.; Kreuer, K.-D. The mechanism of proton conduction in phosphoric acid. Nature Chem 2012, 4, 461– 466,  DOI: 10.1038/nchem.1329
      35
      The mechanism of proton conduction in phosphoric acid
      Vilciauskas, Linas; Tuckerman, Mark E.; Bester, Gabriel; Paddison, Stephen J.; Kreuer, Klaus-Dieter
      Nature Chemistry (2012), 4 (6), 461-466CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
      Neat liq. H3PO4 has the highest intrinsic proton cond. of any known substance and is a useful model for understanding proton transport in other phosphate-based systems in biol. and clean energy technologies. Here, the authors present an ab initio mol. dynamics study that reveals, for the 1st time, the microscopic mechanism of this high proton cond. Anomalously fast proton transport in H-bonded systems involves a structural diffusion mechanism in which intramol. proton transfer is driven by specific H bond rearrangements in the surrounding environment. Aq. media transport excess charge defects through local H bond rearrangements that drive individual proton transfer reactions. But strong, polarizable H bonds in H3PO4 produce coupled proton motion and a pronounced protic dielec. response of the medium, giving extended, polarized H-bonded chains. The interplay between these chains and a frustrated H-bond network gives rise to the high proton cond.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XlvVKmt7o%253D&md5=1a33fce24b92b02a36a2442b2690128d
    36. 36
      Atanasov, V.; Bürger, M.; Lyonnard, S.; Porcar, L.; Kerres, J. Sulfonated poly(pentafluorostyrene): Synthesis & characterization. Solid State Ionics 2013, 252, 75– 83,  DOI: 10.1016/j.ssi.2013.06.010
      36
      Sulfonated poly(pentafluorostyrene): Synthesis & characterization
      Atanasov, Vladimir; Buerger, Matthias; Lyonnard, Sandrine; Porcar, Lionel; Kerres, Jochen
      Solid State Ionics (2013), 252 (), 75-83CODEN: SSIOD3; ISSN:0167-2738. (Elsevier B.V.)
      Prepn. of a high mol. wt. polypentafluorostyrene (PFS) and sulfonated polypentafluorostyrene (sPFS) is described in this paper. The high mol. wt. PFS was obtained via classical emulsion polymn. reaction, which increased the mol. wt. of PFS of about one order of magnitude higher than the one of the com. polymer. The mol. wt. is a crucial factor for the film forming properties of a polymer membrane, following the concept the higher-the better. Furthermore, we post-sulfonated the PFS by 100% (one sulfonic acid per styrene unit). This provided a polymer possessing very high ion-exchange capacity (IEC = 3.4 mmol g-1) with functional group coupled to the relatively flexible side units (Ph rings). The Ph rings are fluorinated which enhanced the nucleophilic substitution reaction (introduction of the functional groups) and reduced the pKa value of the resulting sulfonic acid (pKa = - 2). The morphol. of sPFS, studied by SANS and SAXS, revealed a high ordering of a nano-phase-sepd. system. All these factors raised the cond. to one of the highest measured on polyelectrolyte (σ = 36 mS cm-1 at T = 160 °C, p(H2O) = 105 Pa). This value is one order of magnitude higher than the cond. of Nafion 117 measured under the same conditions.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1Shs7rI&md5=2c27f5b3fdb625ac7a3164b56d609f2a
    37. 37
      Atanasov, V.; Lee, A. S.; Park, E. J.; Maurya, S.; Baca, E. D.; Fujimoto, C.; Hibbs, M.; Matanovic, I.; Kerres, J.; Kim, Y. S. Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells. Nat. Mater. 2021, 20, 370– 377,  DOI: 10.1038/s41563-020-00841-z
      37
      Synergistically integrated phosphonated poly(pentafluorostyrene) for fuel cells
      Atanasov, Vladimir; Lee, Albert S.; Park, Eun Joo; Maurya, Sandip; Baca, Ehren D.; Fujimoto, Cy; Hibbs, Michael; Matanovic, Ivana; Kerres, Jochen; Kim, Yu Seung
      Nature Materials (2021), 20 (3), 370-377CODEN: NMAACR; ISSN:1476-1122. (Nature Research)
      Modern electrochem. energy conversion devices require more advanced proton conductors for their broad applications. Phosphonated polymers have been proposed as anhyd. proton conductors for fuel cells. However, the anhydride formation of phosphonic acid functional groups lowers proton cond. and this prevents the use of phosphonated polymers in fuel cell applications. Here, we report a poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid) that does not undergo anhydride formation and thus maintains protonic cond. above 200°C. We use the phosphonated polymer in fuel cell electrodes with an ion-pair coordinated membrane in a membrane electrode assembly. This synergistically integrated fuel cell reached peak power densities of 1,130 mW cm-2 at 160°C and 1,740 mW cm-2 at 240°C under H2/O2 conditions, substantially outperforming polybenzimidazole- and metal phosphate-based fuel cells. Our result indicates a pathway towards using phosphonated polymers in high-performance fuel cells under hot and dry operating conditions.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFaiurnJ&md5=6b31b483634e5fc8cfeed4bee5d3043a
    38. 38
      Elabd, Y. A.; Hickner, M. A. Block Copolymers for Fuel Cells. Macromolecules 2011, 44, 1– 11,  DOI: 10.1021/ma101247c
      38
      Block Copolymers for Fuel Cells
      Elabd, Yossef A.; Hickner, Michael A.
      Macromolecules (Washington, DC, United States) (2011), 44 (1), 1-11CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      A review. Ion-contg. block copolymers hold promise as next-generation proton exchange membranes in hydrogen and methanol fuel cells. These materials self-assembled ordered nanostructures facilitate proton transport over a wide range of conditions, a requirement for robust fuel cell performance. In this perspective, we present an overview of the morphol. and transport properties of ion-contg. block copolymers that have been studied to gain insight into the fundamental behavior of these materials and, in some cases, are targeted toward applications in fuel cells and other electrochem. devices. We discuss the challenges assocd. with predicting and obtaining well-ordered morphologies in block copolymers with high ion content, particularly those with chemistries that can withstand the chem. and mech. stresses of the fuel cell, such as arom. backbone block copolymers. New opportunities for ion-contg. block copolymers in alk. membrane fuel cells are also reviewed.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsV2lu7bE&md5=78705f4268b9207c8b0f7d6924e969b2
    39. 39
      Bae, B.; Miyatake, K.; Watanabe, M. Synthesis and properties of sulfonated block copolymers having fluorenyl groups for fuel-cell applications. ACS Applied Materials & Interfaces 2009, 1, 1279– 1286,  DOI: 10.1021/am900165w
      39
      Synthesis and Properties of Sulfonated Block Copolymers Having Fluorenyl Groups for Fuel-Cell Applications
      Bae, Byungchan; Miyatake, Kenji; Watanabe, Masahiro
      ACS Applied Materials & Interfaces (2009), 1 (6), 1279-1286CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
      A series of sulfonated poly(arylene ether sulfone)s (SPEs) block copolymers contg. fluorenyl groups were synthesized. Bis(4-fluorophenyl)sulfone (FPS) and 2,2-bis(4-hydroxy-3,5-dimethylpheny)propane were used as comonomers for hydrophobic blocks, whereas FPS and 9,9-bis(4-hydroxyphenyl)fluorene were used as hydrophilic blocks. Sulfonation with chlorosulfonic acid gave sulfonated block copolymers with mol. wt. (Mw) higher than 150 kDa. Proton cond. of the SPE block copolymer with the ion exchange capacity (IEC) = 2.20 mequiv/g was 0.14 S/cm [80% relative humidity (RH)] and 0.02 S/cm (40% RH) at 80°, which is higher or comparable to that of a perfluorinated ionomer (Nafion) membrane. The longer hydrophilic and hydrophobic blocks resulted in higher water uptake and higher proton cond. Scanning transmission electron microscopy observation revealed that phase sepn. of the SPE block copolymers was more pronounced than that of the SPE random copolymers. The SPE block copolymer membranes showed higher mech. properties than those of the random ones. With these properties, the SPE block copolymer membranes seem promising for fuel-cell applications.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXmslOltrY%253D&md5=23caaf01c4b93022dc05bfaab3edfba3
    40. 40
      Shi, Z.; Holdcroft, S. Synthesis and Proton Conductivity of Partially Sulfonated Poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) Block Copolymers. Macromolecules 2005, 38, 4193– 4201,  DOI: 10.1021/ma0477549
      40
      Synthesis and Proton Conductivity of Partially Sulfonated Poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) Block Copolymers
      Shi, Zhiqing; Holdcroft, Steven
      Macromolecules (2005), 38 (10), 4193-4201CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      A series of novel, amphiphilic block copolymers comprising of sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) [P(VDF-co-HFP)-b-SPS] were synthesized. The no.-av. mol. wts. of the fluorous and polystyrene segments were 17 900 and 8100 g/mol, resp. Sulfonation of the polystyrene segment to different extents provided a series of polymers which were cast into films to yield proton exchange membranes with varying ion exchange capacity (IEC). Proton cond. of the membranes increased significantly when the IEC was increased from 0.5 to 1.2 mmol/g. For 0.9-1.2 mmol/g IEC membranes, the cond. was similar to Nafion 117, significantly higher than random copolymers of polystyrene and sulfonated polystyrene, and twice that of nonfluorous block copolymer membranes based on sulfonated poly(styrene-b-[ethylene-co-butylene]-b-styrene) (S-SEBS) and sulfonated hydrogenated poly(butadiene-b-styrene) (S-HPBS) copolymers. TEM revealed a disruption in ordered morphol. with increasing degree of sulfonation. Morphol. structures of membranes having 0.6-1.2 mmol/g IEC comprised of interconnected networks of ion channels, each of 8-15 nm width.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXjt1Smt7k%253D&md5=114ebb2bbd2fd6df8a6955efffd5d15c
    41. 41
      Tsang, E. M. W.; Zhang, Z.; Shi, Z.; Soboleva, T.; Holdcroft, S. Considerations of macromolecular structure in the design of proton conducting polymer membranes: graft versus diblock polyelectrolytes. J. Am. Chem. Soc. 2007, 129, 15106– 15107,  DOI: 10.1021/ja074765j
      41
      Considerations of Macromolecular Structure in the Design of Proton Conducting Polymer Membranes: Graft versus Diblock Polyelectrolytes
      Tsang, Emily M. W.; Zhang, Zhaobin; Shi, Zhiqing; Soboleva, Tatyana; Holdcroft, Steven
      Journal of the American Chemical Society (2007), 129 (49), 15106-15107CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      Model fluorous-ionic copolymer systems were synthesized and studied to study the role of polymer architecture on morphol. and properties of solid polymer electrolytes. Two types of compositionally similar but architecturally distinct copolymers were studied: P(VDF-co-CTFE)-g-SPS graft copolymers, comprising a hydrophobic fluorous backbone and sulfonated styrene side chains, and P(VDF-co-HFP)-b-SPS diblock copolymers, comprising a hydrophobic fluorous segment linearly connected to a sulfonated styrenic segment. The macromol. structure plays an important role in detg. membrane morphol. Graft membranes possess a small ionic cluster morphol. while diblock membranes possess a lamellar-like morphol. These morphol. differences affect the threshold of ionic percolation, water sorption, proton mobility and concn., proton cond., and anisotropy of ion conduction.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhtlWmu7zI&md5=5dd3e11ab9d42cccba453705d3a15a20
    42. 42
      Fritsch, B.; Wu, M.; Hutzler, A.; Zhou, D.; Spruit, R.; Vogl, L.; Will, J.; Hugo Pérez Garza, H.; März, M.; Jank, M. P. M.; Spiecker, E. Sub-Kelvin thermometry for evaluating the local temperature stability within in situ TEM gas cells. Ultramicroscopy 2022, 235, 113494,  DOI: 10.1016/j.ultramic.2022.113494
      42
      Sub-Kelvin thermometry for evaluating the local temperature stability within in situ TEM gas cells
      Fritsch, Birk; Wu, Mingjian; Hutzler, Andreas; Zhou, Dan; Spruit, Ronald; Vogl, Lilian; Will, Johannes; Hugo Perez Garza, H.; Maerz, Martin; Jank, Michael P. M.; Spiecker, Erdmann
      Ultramicroscopy (2022), 235 (), 113494CODEN: ULTRD6; ISSN:0304-3991. (Elsevier B.V.)
      In situ TEM utilizing windowed gas cells is a promising technique for studying catalytic processes, wherein temp. is one of the most important parameters to be controlled. Current gas cells are only capable of temp. measurement on a global (mm) scale, although the local temp. at the spot of observation (μm to nm scale) may significantly differ. Thus, local temp. fluctuations caused by gas flow and heat dissipation dynamics remain undetected when solely relying on the global device feedback. In this study, we overcome this limitation by measuring the specimen temp. in situ utilizing parallel-beam electron diffraction at gold nanoparticles. By combining this technique with an advanced data processing algorithm, we achieve sub-Kelvin precision in both, vacuum as well as gaseous environments. Mitigating charging effects is furthermore shown to minimize systematic errors. By utilizing this method, we characterize the local thermal stability of a state-of-the-art gas cell equipped with heating capability in vacuum and under various gas-flow conditions. Our findings provide crucial ref. for in situ investigations into catalysis.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xls1Kntr0%253D&md5=dd4e110785ab0467fe27599561f9a712

  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmaterialslett.3c00569.

    • Simulation of POS-PWN-66 nanophase; NMRs of the block-co-polymers; DSC curves of POS-PPFS and POS-PWN60; DMA measurements of POS-b-PWN-60 and PWN-75; experimental details of membrane characterization; experimental details of nanophase imaging; analysis of STEM and simulation images of POS-PWN; NMR and GPC methods (PDF)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.