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Nano‐hybrid membranes made up using sulfonated (poly‐arylene ether ketone) (SPAEK) and sulfonated graphene oxide (SGO) with various weight ratio i.e., 0.5, 1 and/or 1.5 wt % were fabricated with a traditional solvent casting approach and their appropriateness for the potential application of proton exchange membrane fuel cells (PEMFCs) was probed. Structural characteristics of membranes were substantiated by 1H NMR, FT‐IR, and XRD. The composite membranes revealed the outstanding thermal property with a primary weight drop at temperature of 200 °C, as proved by TGA analysis. TM‐AFM images of composite membrane revealed the phase separated morphology of hydrophobic and hydrophilic regions, which afford the wide pathways for swift and easy conduction of protons. Additionally, integration of SGO dramatically raises the water absorption and consequently proton conductivity, whereas it decreases activation energy needed to transfer the protons via membrane. Proton conductivity value of 124 mS/cm was acquired using 1.5 wt % SGO/SPAEK composite membrane with a higher volume of water absorption i.e., 19%. [ABSTRACT FROM AUTHOR]

Abstract: Poor durability of polymer electrolyte membranes is one of the most limiting factors of proton exchange membrane fuel cell (PEMFC). Hydrogen peroxide which is formed electrochemically or chemically during operation is one of the potential deteriorating factors, particularly for polyaromatic membranes. To be able to increase membrane durability, the aging path involved must be elucidated. To give an insight into the degradation mechanism of sulfonated polyaryl ether ketones (sPAEK) a study on model compound has been performed. Each species produced has been collected by liquid chromatography and identified by NMR, IR and mass spectroscopies. We have demonstrated that degradation proceeds through the addition of a hydroxyl radical on the aromatic ring. Then, the oxidation of these phenolic groups leads to several chain scissions. On the basis of these experiments, a strategy can be drawn to improve the membrane durability. [Copyright &y& Elsevier]

The series of sulfonated poly(arylene ether ketone) (SPAEK) block copolymers with controlled F-oligomer length bearing pendant diphenyl unit were synthesized via a polycondensation reaction. Sulfonation was verified by 1 H NMR analysis to introduce sulfonic acid group selectively and intensively on the pendant diphenyl unit of polymer backbones. The SPAEK membranes fabricated by the solution casting approach were very transparent and flexible with the thickness of ∼50 μm. These membranes with different F-oligomer lengths were investigated to the physiochemical properties such as water absorption, dimensional stability, ion exchange capacity, and proton conductivity. As a result, the SPAEK membranes (X4.8Y8.8, X7.5Y8.8, and X9.1Y8.8) in accordance to increasing the length of hydrophilic oligomer showed excellent proton conductivity in range of 131-154 mS cm -1 compared to Nafion-115 (131 mS cm -1 ) at 90 °C under 100% relative humidity (RH). Among the SPAEK membranes, proton conductivity of SPAEK X9.1Y8.8 (140.7 mS cm -1 ) is higher than that of Nafion-115 (102 mS cm -1 ) at 90 °C under 80% RH. The atomic force microscopy image demonstrated that number of ion transport channels is increased with increase in the length of hydrophilic oligomer in the main chains, and the morphology is proved to be related to the proton conductivity. The synthesized SPAEK membrane exhibited a maximum power density of 324 mW cm -2 , which is higher than that of Nafion-115 (291 mW cm -2 ) at 60 °C under 100% RH.