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Summary: In this work, sulfonated diblock copolymers (SDBCs) were prepared by polycondensation of sulfonated poly(ether‐ether‐ketone) (SPEEK) and hydrophobic oligomer, which were combined with sintered anatase titanium oxide (S‐An‐TiO2) to create a hybrid membrane for apply in proton exchange membrane fuel cells (PEMFCs) operating with low relative humidity (RH). Then, a series of composite membranes (SDBC/S‐An‐TiO2) were prepared by varying the wt% of S‐An‐TiO2 blended with SDBC. The results showed that appropriate quantity (ie, 15 wt%) of S‐An‐TiO2 can significantly improve the proton conductivity and physiochemical properties of prepared composite membrane, as well as the PEMFC performance and durability under 20% RH. The 1.5 wt% of SDBC/S‐An‐TiO2 offers high current output, power output, and durability values at 60°C under 20% RH, which are 0.207 A cm−2, 0.074 W cm−2 and over 90 hours, respectively. These results can be attributed to the good interfacial compatibility between S‐An‐TiO2 and SDBC. [ABSTRACT FROM AUTHOR]

A series of sulfonated poly(arylene ether sulfone) block copolymers with aliphatic chains (SPAES-LA) to lend structural flexibility in the polymer backbone have been synthesized to prepare proton exchange membranes (PEMs) showing improved electrochemical performance and dimensional/oxidative stabilities. The SPAES-LAs, bearing different hydrophilic/hydrophobic segment lengths, are prepared via polycondensation and sulfonation reactions. The sulfonation reaction occurs in specific fluorenylidene units by using chlorosulfonic acid. The SPAES-LA membrane, fabricated by solvent casting method, exhibits remarkable dimensional/thermal stabilities. Moreover, proton conductivity of as-prepared SPAES-LA membranes demonstrates significant improvement with expansion of ion clusters which is due to the increased hydrophilic volume ratio. In particular, the SPAES-LA-X12Y28 membrane exhibited heightened proton conductivity of 158.4 mS cm−1 as well as suitable dimensional stability and durability towards radical oxidation, due to an effective well-defined hydrophilic-hydrophobic interface. Furthermore, H 2 /O 2 fuel cell performance using SPAES-LA-X12Y28 membrane achieves a maximum power density of 232.02 mW cm−2, a result which points out that SPAES-LA membranes show great potential for applications of polymer electrolyte membrane. Image 1 • The block copolymers are synthesized via controlling oligomer lengths. • The fabricated membranes show desirable thermo-oxidative stability. • The membranes showed high physio-chemical properties. • The as-prepared membranes exhibit high ionic conductivity and unit-cell performance. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and properties of densely sulfonated poly(arylene biphenylsulfone ketone) block copolymer and its composite membranes including phosphotungstic acid (PWA) were investigated. The chemical structure of the block copolymers was characterized by FT-IR, 1H-NMR, and GPC. The block copolymer composite membranes were prepared by mixing the block copolymer with a commercial PWA. The composite membranes have shown not only good thermal stability (decomposition temperature in nitrogen >250°C), but also lower water uptake than the unfilled membranes. Their crystalline phases and morphologies have been confirmed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FSEM), respectively. The composite membranes displayed relevant ion exchange capacity (IEC), as well as good proton conductivity especially at elevated temperature. The proton conductivity of the Block-19/PWA-30 composite membrane (IEC 1.58meqg−1) reached the maximum of 97mScm−1 at 90°C under 100% relative humidity (RH), which is comparable to Nafion-117. The fabricated composite membrane exhibited a maximum fuel cell power density of 150mWcm−2, which was much higher that of Block-19 membrane and can be considered as a candidate for potential application in fuelcells. [Copyright &y& Elsevier]

Novel anion conductive nanocomposite membranes with superb hydroxide conductivity and chemical durability in alkaline conditions were prepared by the introduction of quaternary ammonium functionalized graphene oxide (Q-GO) into quaternized poly(arylene ether) (QPAE) random copolymer. Q-GO containing amino silane units, which induce ion cluster formation in the polymer matrix, was synthesized using (3-aminopropyl)triethoxysilane (APTS) and (3-bromopropyl)trimethyl ammonium bromide (PTMA) as the main quaternization reagents. The chemical structures and morphologies of the polymers and inorganic nanofillers were characterized by 1H NMR, FT-IR, FE-SEM, XPS, and SAXS. GO-(APTS- c -PTMA), the so called Q-GO, was used to expand the ion transfer sites and improve the physicochemical stability of the membrane. The electrochemical properties, thermal/mechanical properties, and chemical stabilities of the anion exchange membranes (AEMs) were investigated in accordance with different contents of GO-(APTS- c -PTMA). The π-π bonds between the polymer matrix and the Q-GO resulted in improved dimensional stability and mechanical properties in the composite membrane. The QPAE/GO-(APTS- c -PTMA) 0.7 wt% membrane showed the highest hydroxide conductivity of 114.2 mS cm−1 at 90 °C with an ion exchange capacity of 1.45 mmol g−1, which is 2.07 times higher than the pristine membrane (55.1 mS cm−1 at 90 °C). Furthermore, the single-cell performance of the QPAE/GO-(APTS- c -PTMA) 0.7 wt% as an AEM showed an excellent maximum power density of 135.8 mW cm−2 at 70 °C. Image 1 • Cheap and easy method for crosslinked anion exchange membrane (AEM) preparation for anion exchange membrane fuel cells AEMFC. • The composite AEMs showed highest hydroxide conductivity. • The prepared composite AEMs exhibit long-term chemical stability (>20 days). • The cell was stably operated at 60 °C for 120 h. [ABSTRACT FROM AUTHOR]

We designed and synthesized a series of sulfonated poly(arylene ether sulfone) (SPES) with different hydrophilic or hydrophobic oligomer ratios using poly-condensation strategy. Afterward, we fabricated the corresponding membranes via a solution-casting approach. We verified the SPES membrane chemical structure using nuclear magnetic resonance (1H NMR) and confirmed the resulting oligomer ratio. Field-emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) results revealed that we effectively attained phase separation of the SPES membrane along with an increased hydrophilic oligomer ratio. Thermal stability, glass transition temperature (Tg) and membrane elongation increased with the ratio of hydrophilic oligomers. SPES membranes with higher hydrophilic oligomer ratios exhibited superior water uptake, ion-exchange capacity, contact angle and water sorption, while retaining reasonable swelling degree. The proton conductivity results showed that SPES containing higher amounts of hydrophilic oligomers provided a 74.7 mS cm−1 proton conductivity at 90 °C, which is better than other SPES membranes, but slightly lower than that of Nafion-117 membrane. When integrating SPES membranes with proton-exchange membrane fuel cells (PEMFCs) at 60 °C and 80% relative humidity (RH), the PEMFC power density exhibited a similar increment-pattern like proton conductivity pattern. [ABSTRACT FROM AUTHOR]