Correlation between Morphology, Water Uptake, and Proton Conductivity in Radiation Grafted Proton Exchange Membranes

Balog, Sandor; Gasser, Urs; Mortensen, K.; Gubler, Lorenz; Youcef, Hicham Ben; Scherer, Guenther G.

doi:10.1557/proc-1269-ff02-05

Cited by 5 publications

(11 citation statements)

References 19 publications

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“…This result suggests that the PS-graft regions existed at regular spatial intervals of 30 nm. In previous SANS measurements of the FEP-and ETFE-based PS-grafted films, 7,9 this peak was also observed at a similar q. However, the interpretation of this peak was not so clear in these studies.…”

Section: Resultsmentioning

confidence: 67%

“…However, the interpretation of this peak was not so clear in these studies. 7,9 Thus, the ordered structures responsible for the observed peak in the PS-grafted film were considered.…”

Section: Resultsmentioning

confidence: 99%

“…This conclusion is quite opposite to Balog's work, in which the PSSA chains were assumed to be mixed with the ETFE chains. 7 PEMs in the dried and hydrated states Figure 5 shows the SANS profiles of the PEMs in the dried and hydrated states. The hydrated PEMs also exhibited shoulder-like peaks and the obtained d P values are shown in Figure 4.…”

Section: Grafted Films and Pems With Different Graft Contentsmentioning

confidence: 99%

“…Comparisons of the results for the ETFE, PS-grafted films and PEMs enabled us to probe the crystal morphology. Balog et al 7 also performed SANS measurement on ETFE-based graft-type PEMs, in which the graft chains were crosslinked with divinylbenzene. They focused on the effect of the divinylbenzene crosslink level on the structures of PEMs possessing a narrow range of IECs.…”

Section: Introductionmentioning

confidence: 99%

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Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

Sawada

Yamaguchi

Putra

et al. 2012

Polym J

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The nanoscale structures of graft-type polymer electrolyte membranes (PEMs), prepared by radiation-induced graft polymerization (grafting) of styrene onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films followed by sulfonation, were investigated using a small-angle neutron scattering (SANS) technique. For comparison, SANS measurements were also performed on two precursor materials, the original ETFE film and polystyrene (PS)-grafted films. The SANS profiles of the grafted films showed shoulder peaks at a d-spacing of B30 nm, which were attributed to the PS grafts introduced into the amorphous phases between the ETFE lamellar crystals. This grafting would result in the construction of a stack structure with alternating ETFE crystalline and PS-grafted layers as a repeating unit. In the ETFE PEMs, the spacing of the PS sulfonic acid (PSSA) grafts and ETFE crystals increased because the graft regions were enlarged by the volume of the attached sulfonic acid groups. Interestingly, the graft/crystal stack spacing in the PEMs did not increase from the dry-to fully-hydrated states. This finding implies restricted water absorption in the PSSA grafts between the ETFE lamellar crystals. In other words, most of the PSSA grafts introduced outside of the lamellae were considered to be hydrated and to act as proton conduction pathways.

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Section: Resultsmentioning

confidence: 67%

“…However, the interpretation of this peak was not so clear in these studies. 7,9 Thus, the ordered structures responsible for the observed peak in the PS-grafted film were considered.…”

Section: Resultsmentioning

confidence: 99%

Section: Grafted Films and Pems With Different Graft Contentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

Sawada

Yamaguchi

Putra

et al. 2012

Polym J

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“…Here, it is worth noting the multiscale nature of proton conduction in PEMs, since the tortuosity and size of ionic channels within each hydrated site affects in turn the value of

through the (local effective) proton diffusivity,

. As shown in previous works, the membrane processing conditions significantly affect the multiscale morphology of block copolymer membranes [ 75 , 76 , 77 , 78 , 79 , 80 ]. For instance, Assumma et al [ 75 ] reported a ten-fold increase in proton conductivity after thermal annealing of SPAS multiblock copolymer membranes.…”

Section: Resultsmentioning

confidence: 91%

On the Conductivity of Proton-Exchange Membranes Based on Multiblock Copolymers of Sulfonated Polysulfone and Polyphenylsulfone: An Experimental and Modeling Study

et al. 2021

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The effect of relative humidity (RH) and degree of sulfonation (DS) on the ionic conductivity and water uptake of proton-exchange membranes based on sulfonated multiblock copolymers composed of polysulfone (PSU) and polyphenylsulfone (PPSU) is examined experimentally and numerically. Three membranes with a different DS and ion-exchange capacity are analyzed. The heterogeneous structure of the membranes shows a random distribution of sulfonated (hydrophilic) and non-sulfonated (hydrophobic) domains, whose proton conductivity is modeled based on percolation theory. The mesoscopic model solves simplified Nernst–Planck and charge conservation equations on a random cubic network. Good agreement is found between the measured ionic conductivity and water uptake and the model predictions. The ionic conductivity increases with RH due to both the growth of the hydrated volume available for conduction and the decrease of the tortuosity of ionic transport pathways. Moreover, the results show that the ionic conductivity increases nonlinearly with DS, experiencing a strong rise when the DS is varied from 0.45 to 0.70, even though the water uptake of the membranes remains nearly the same. In contrast, the increase of the ionic conductivity between DS=0.70 and DS=0.79 is significantly lower, but the water uptake increases sharply. This is explained by the lack of microphase separation of both copolymer blocks when the DS is exceedingly high. Encouragingly, the copolymer membranes demonstrate a similar performance to Nafion under well hydrated conditions, which can be further optimized by a combination of numerical modeling and experimental characterization to develop new-generation membranes with better properties.

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Radiation Grafted Ion-Conducting Membranes: The Influence of Variations in Base Film Nanostructure

et al. 2016

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The proton exchange membrane (PEM) is a key element of a polymer electrolyte fuel cell, and radiation-grafting is an attractive option for the synthesis of PEMs. Via a systematic investigation of a well-defined model material, sulfonated polystyrene grafted poly(ethylene-alt-tetrafluoroethylene), ETFE-g-PS(SA), we show that the performance and stability of radiation-grafted PEMs in fuel cells strongly depends on the microstructure of the underlying base polymer. The nanoscale structure of the base polymers, grafted films, and membranes is probed by small-angle scattering, and the nanoscale proton dynamics is probed by quasi-elastic neutron scattering. The results of these techniques correlated with fuel cell relevant propertiesincluding proton conductivity and water uptakeand fuel cell performance clearly indicate that differences in the arrangement of the crystalline phase in the otherwise chemically identical semicrystalline base films can have considerable impact, representing an essential aspect to consider in the development of proton exchange membranes prepared via preirradiation grafting.

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Correlation between Morphology, Water Uptake, and Proton Conductivity in Radiation Grafted Proton Exchange Membranes

Cited by 5 publications

References 19 publications

Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

On the Conductivity of Proton-Exchange Membranes Based on Multiblock Copolymers of Sulfonated Polysulfone and Polyphenylsulfone: An Experimental and Modeling Study

Radiation Grafted Ion-Conducting Membranes: The Influence of Variations in Base Film Nanostructure

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