SAXS and NMR Analysis for the Cast Solvent Effect on sPEEK Membrane Properties

Luu, Dinh Xuan; Cho, Eun‐Bum; Han, Oc Hee; Kim, Dong Jin

doi:10.1021/jp9063752

Cited by 7 publications

(7 citation statements)

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“…The characteristic dimension of the ionic domains for the 5 wt % TPPS/sPEEK composite membrane is 3.7 nm. These values are larger than what was reported for pristine sPEEK cast from DMAc, with both lower and the same degree of sulfonation . The increase in intensity and the shift of the ionomer peak toward lower angles (see inset of Figure ) confirm that the porphyrins, in their different forms, are predominantly located inside the ionic domains.…”

Section: Results and Discussionmentioning

confidence: 51%

“…These values are larger than what was reported for pristine sPEEK cast from DMAc, with both lower 17 and the same degree of sulfonation. 65 The increase in intensity and the shift of the ionomer peak toward lower angles (see inset of Figure 4) confirm that the porphyrins, in their different forms, are predominantly located inside the ionic domains. The presence of the porphyrins also has an influence on the membrane structure at larger length scales.…”

Section: ■ Results and Discussionmentioning

confidence: 63%

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Porphyrin/sPEEK Membranes with Improved Conductivity and Durability for PEFC Technology

Carbone

Gaeta

Romeo

et al. 2018

ACS Appl. Energy Mater.

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Advanced composite membranes have been obtained by incorporation of the meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) into a sulfonated poly(etheretherketone) (sPEEK). The presence of porphyrins in their monomeric, dimeric, and aggregated forms into the membrane ionic domains have been investigated by static and time-resolved spectroscopic techniques. In particular, we succeeded in modulating the percentage of the different porphyrin species present into the proton-conducting channels acting on the dye load in the range 0.35−5 wt % porphyrin/polymer. The nanostructure of all the composite membranes has been investigated by small-angle X-ray scattering. This latter shows how the presence of TPPS porphyrins into the membrane ionic domains induces a reorganization of polymer chains in a more stable and organized lamellar-like structure with respect to the pristine polymeric matrix. Finally, the composite membranes have been used as proton exchange membrane for fuel cells (PEFCs) technology. The presence of porphyrins improved the performance of the membranes in terms of proton conductivity and stability. In particular, the 0.77 wt % composite membrane has been tested in a PEFC single cell simulating the operative conditions typical for portable applications, highlighting an improved stability compared to that of the sPEEK pristine membranes.

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Section: Results and Discussionmentioning

confidence: 51%

Section: ■ Results and Discussionmentioning

confidence: 63%

Porphyrin/sPEEK Membranes with Improved Conductivity and Durability for PEFC Technology

Carbone

Gaeta

Romeo

et al. 2018

ACS Appl. Energy Mater.

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“…Using a Bragg estimate from the q max values (i.e., d Bragg = 2π/q max ), this yields an intermultiplet domain distance of 19−29 Å, which is consistent with previous studies of conventionally sulfonated SPEEK membranes in the literature. 59,62,63 Fitting of the ionomer peaks using a size distribution model with a spheroid form factor and hard sphere structure factor (details of the fitting process are described in the Supporting Information, Figures S7 and S8) shows that the multiplet radii of the random SPEEK membranes increase from 5.0 to 5.9 Å as the degree of sulfonation increases from 6.0 to 10.9 mol % (Table S5). Gebel and Gomes have similarly reported small ionic domains with radii of 4−6 Å for SPEEK membranes using various fitting procedures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Blocky Ionomers via Sulfonation of Poly(ether ether ketone) in the Semicrystalline Gel State

et al. 2018

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Blocky sulfonated poly(ether ether ketone) (SPEEK) ionomers were synthesized by postpolymerization functionalization in the gel state. Matched sets of blocky and random SPEEK with ion contents between 3 and 11 mol % were prepared, and the thermal transitions and crystallization kinetics were examined using differential scanning calorimetry (DSC). At similar ion contents, the blocky SPEEK exhibited higher crystallizability and faster crystallization kinetics than random SPEEK. Reduced scattering contrast in the USAXS/ SAXS/WAXD analysis of the blocky SPEEK copolymer membranes, relative to the random analogues, suggested that the ionic aggregates in blocky SPEEK were distributed in close proximity to the crystalline domains. Despite similar water uptake values for the low ion content random and blocky SPEEK membranes, the blocky SPEEK exhibited higher proton conductivities than their random analogues. At significantly higher ion contents (45 mol %), the blocky SPEEK membranes remained semicrystalline, showed controlled water uptake, and exhibited a 2.5 times higher conductivity over that of the amorphous, random analogues. Moreover, these new blocky, semicrystalline SPEEK membranes were found to exhibit a proton conductivity that was comparable to that of the benchmark 1100 EW Nafion.

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“…12 The literature on sPEEK microstructure is scarce and quite recent. 1,[13][14][15][16][17] In addition the possibility to design sPEEK membranes with various degrees of sulfonation (DS), to use different casting solvents and membrane cleaning procedures gives rise to a wide span of SAXS spectra with characteristic peaks located at different scattering ranges. A clear picture of the sPEEK membrane morphology can thus hardly emerge.…”

Section: Introductionmentioning

confidence: 99%

A new interpretation of SAXS peaks in sulfonated poly(ether ether ketone) (sPEEK) membranes for fuel cells

Mendil‐Jakani

Lopez

Legrand

et al. 2014

Phys. Chem. Chem. Phys.

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The structure of a commercial sulfonated poly(ether ether ketone) (sPEEK) membrane was analyzed by Small-Angle X-Ray Scattering (SAXS) for different water uptakes obtained after immersion in liquid water at various temperatures. For low membrane swelling, the SAXS profile displays only a wide-angle peak in the 0.2-0.3 Å(-1) region. As the membrane swells, two supplementary correlation peaks arise and shift towards small angles, which are the signature of a structural evolution of the membrane, whereas the wide angle peak remains stable. The SAXS spectra of sPEEK membranes can thus display three correlation peaks simultaneously. Therefore we propose a new interpretation of these SAXS spectra which conclude that the two small angle peaks are attributed to the so-called matrix and ionomer peaks and the wide-angle peak is ascribed to the mean separation distance between sulfonic acid groups grafted onto the polymer backbone. This peak attribution implies that the sPEEK nano-phase separation is triggered by an immersion in hot water (ionomer peak apparition). Our new peak attribution was confirmed by studying the impact of temperature, electron density contrast and ionic exchange capacity.

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SAXS and NMR Analysis for the Cast Solvent Effect on sPEEK Membrane Properties

Cited by 7 publications

References 0 publications

Porphyrin/sPEEK Membranes with Improved Conductivity and Durability for PEFC Technology

Porphyrin/sPEEK Membranes with Improved Conductivity and Durability for PEFC Technology

Blocky Ionomers via Sulfonation of Poly(ether ether ketone) in the Semicrystalline Gel State

A new interpretation of SAXS peaks in sulfonated poly(ether ether ketone) (sPEEK) membranes for fuel cells

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