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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]

Summary: Organic‐inorganic composite membranes were prepared by introducing silicon dioxide (SiO2) or functionalized SiO2 (ƒ‐SiO2) with various particle sizes into sulfonated poly (arylene ether ketone) (SPAEK) containing pendant groups, and the membrane was manufactured via directly casting which is a cost‐competitive method. The structure and morphology of the composite membranes were confirmed by 1H NMR, FT‐IR, XRD, and FE‐SEM analysis which demonstrated that inorganic nanofillers were successfully introduced. The FE‐SEM surface images showed that SiO2 and ƒ‐SiO2 particles were very well dispersed within the membrane sheets. The water uptake and swelling ratio of the composite membranes including SiO2 or ƒ‐SiO2 almost did not change when compared with the pristine SPAEK membrane. All fabricated membranes demonstrated good thermal/dimensional stabilities, robust mechanical behavior, and excellent proton conductivity. In particular, the SPAEK/ƒ‐SiO2 composite membranes exhibited improved ionic conductivity compared with the pristine membrane at 70% relative humidity (RH) due to hydrogen bonding between ─SO3H groups of functionalized inorganic filler and polymer backbone. Furthermore, the maximum power density of SPAEK/ƒ‐SiO2 reached as high as 273.11 mW cm−2 at 60°C under 70% RH. Therefore, the composite membranes with ƒ‐SiO2 testify to great potential as polymer electrolyte membrane. [ABSTRACT FROM AUTHOR]

The development of potential and novel proton exchange membranes (PEMs) is imperative for the further commercialization of PEM fuel cells (PEMFCs). In this work, phosphotungstic acid (PWA) and graphene oxide (GO) were integrated into sulfonated poly(arylene ether) (SPAE) through a solution casting approach to create a potential composite membrane for PEMFC applications. Thermal stability of membranes was observed using thermogravimetric analysis (TGA), and the SPAE/GO/PWA membranes exhibited high thermal stability compared to pristine SPAE membranes, owing to the interaction between SPAEK, GO, and PWA. By using a scanning electron microscope (SEM) and atomic force microscope (AFM), we observed that GO and PWA were evenly distributed throughout the SPAE matrix. The SPAE/GO/PWA composite membrane comprising 0.7 wt% GO and 36 wt% PWA exhibited a maximum proton conductivity of 186.3 mS cm−1 at 90 °C under 100% relative humidity (RH). As a result, SPAE/GO/PWA composite membrane exhibited 193.3 mW cm−2 of the maximum power density at 70 °C under 100% RH in PEMFCs. [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]

Sulfonated poly(arylene biphenylether sulfone)-poly(arylene ether) (SPABES-PAE) block copolymers by controlling the molar ratio of SPABES and PAE oligomers were successfully synthesized, and the performances of SPABES-PAE (1:2, 1:1, and 2:1) membranes were compared with Nafion 212. The prepared membranes including fluorinated hydrophobic units were stable against heat, nucleophile attack, and physio-chemical durability during the tests. Moreover, the polymers exhibited better solubility in a variety of solvents. The chemical structure of SPABES-PAEs was investigated by 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). The membrane of SPABES-PAEs was fabricated by the solution casting method, and the membranes were very flexible and transparent with a thickness of 70–90 μm. The morphology of the membranes was observed using atomic force microscope and the ionic domain size was proved by small angle X-ray scattering (SAXS) measurement. The incorporation of polymers including fluorinated units allowed the membranes to provide unprecedented oxidative and dimensional stabilities, as verified from the results of ex situ durability tests and water uptake capacity, respectively. By the collective efforts, we observed an enhanced water retention capacity, reasonable dimensional stability and high proton conductivity, and the peak power density of the SPABES-PAE (2:1) was 333.29 mW·cm−2 at 60 °C under 100% relative humidity (RH). [ABSTRACT FROM AUTHOR]