Polyacrylonitrile‐based proton conducting membranes containing sulfonic acid and tetrazole moieties

Proton conducting membranes based on polymers containing sulfonic acid and tetrazole moieties were developed. Successful syntheses of poly(acrylonitrile‐co ‐styrene sulfonic acid) (PAN‐co ‐PSSA), poly(acrylonitrile‐co ‐5‐vinyl tetrazole) (PAN‐co ‐PVTz), and poly(acrylonitrile‐co ‐5‐vinyl tetrazole‐co ‐styrene sulfonic acid) (PAN‐co ‐PVTz‐co ‐PSSA) were confirmed by ¹H‐nuclear magnetic resonance spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy. Two approaches were performed to study the effects of molar ratio of sulfonic acid to tetrazole and tetrazole content on membrane properties. In the first approach, PAN‐co ‐PSSA was blended with PAN‐co ‐PVTz at three molar ratios. The second approach focused on PAN‐co ‐PVTz‐co ‐PSSA membranes with various tetrazole contents. PAN‐co ‐PSSA membrane was also prepared. All solution‐cast membranes were hydrolytically stable, except for PAN‐co ‐PVTz‐co ‐PSSA with 71% tetrazole. Surface morphologies of blend membranes were studied using scanning electron microscopy, and no phase separation was observed. Water uptake was shown to increase with increasing tetrazole. All membranes exhibited high thermal stability (up to 250 °C) and high storage moduli. Proton conductivity was found to depend significantly on relative humidity. The influences of sulfonic acid to tetrazole ratio and tetrazole content on proton conduction were observed and discussed. A maximum proton conductivity of 7.1 × 10^?3 S/cm at 26 °C was obtained from PAN‐co ‐PSSA membrane. In addition, all tested membranes showed relatively good oxidative stability after treatment in Fenton's reagent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45411.     

Novel imidazole‐grafted hybrid anion exchange membranes based on poly(2,6‐dimethyl‐1,4‐phenylene oxide) for fuel cell applications

Novel organic–inorganic hybrid membranes, based on poly(2,6‐dimethyl‐1,4‐phenylene oxide), have been prepared through 1,2‐dimethylimidazole functional groups and double crosslinking agents including 3‐glycidyloxypropyltrimethoxysilane and tetraethyl orthosilicate by sol–gel process for the purpose of improving the conductivity and alkaline resistance. The structure of membranes was characterized using Fourier‐transform infrared spectra, ¹H NMR, and X‐ray diffraction. The physico‐chemical properties of all membranes were shown in ion exchange capacity, water uptake, stability, and conductivity. Membranes with OH^– conductivity up to 0.022 at 25 °C and 0.036 S cm^?1 at 80 °C. Promisingly, the chemical stability of the resulting membranes remains unchanged after storage in 2 mol dm^?3 KOH at 25 °C over at least 10 days. The tensile strength can be higher than 30 MPa, and the elongation at break (Eb) is in the range 6.68–10.84%. Hence, this hybrid membrane can be potentially applied in alkaline fuel cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46034.     

Effects of microstructural functional polyaniline layers on SPEEK/HPW proton exchange membranes

In this study, a method is developed to fabricate sulfonated poly (ether ether ketone)/phosphotungstic acid‐polyaniline (SPEEK/HPW‐PANI) membranes by in situ polymerization of aniline for the purpose of decreasing the weight loss of HPW in the membranes. The synthesis involves the production of a SPEEK/HPW hybrid membrane followed by different layer of PANI coatings on the membrane surface, and subsequent treatment using drying in vacuum procedures. The scanning electronic microscopy images showed that HPW had good compatibility with SPEEK polymers and energy dispersive X‐ray spectroscopy revealed the successfully doping with HPW and polymerization of PANI. The surface of SPEEK/HPW‐PANI becomes more compact than that of SPEEK/HPW and pure SPEEK, which may lead to reduce the water uptake and swelling property. The proton conductivity was found for the SPEEK/HPW‐PANI‐5 composite membrane (91.53 mS/cm at 80°C) higher than that of pure SPEEK membrane (68.72 mS/cm at 80°C). Better thermal stability was determined in both SPEEK/HPW and SPEEK/HPW‐PANI membranes than pristine SPEEK membrane. Therefore, PANI is a good potential coating for organic–inorganic hybrid e.g. SPEEK/HPW membrane materials to improve their hydrothermal stable properties and SPEEK/HPW PANI is a material that shows promise as a proton exchange membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41033.     

Enhanced proton conductivity from phosphoric acid‐incorporated 3D polyacrylamide‐graft‐starch hydrogel materials for high‐temperature proton exchange membranes

To enhance anhydrous proton conductivity of high‐temperature proton exchange membranes (PEMs), we report here the realization of H₃PO₄‐imbibed three‐dimensional (3D) polyacrylamide‐graft‐starch (PAAm‐g‐starch) hydrogel materials as high‐temperature PEMs using the unique absorption and retention of crosslinked PAAm‐g‐starch to concentrated H₃PO₄ aqueous solution. The 3D framework of PAAm‐g‐starch matrix provides enormous space to keep H₃PO₄ into the porous structure, which can be controlled by adjusting crosslinking agent and initiator dosages. Results show that the H₃PO₄ loading and therefore the proton conductivities of the membranes are significantly enhanced by increasing the amount of crosslinking agent and initiator dosages. Proton conductivities as high as 0.109 S cm^?1 at 180°C under fully anhydrous state are recorded. The high conductivities at high temperatures in combination with the simple preparation, low cost, and scalable matrices demonstrate the potential use of PAAm‐g‐starch hydrogel materials in high‐temperature proton exchange membrane fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40622.     

Basicity‐based screening of aniline derivative for composite proton exchange membranes

The aim of this study was to find a suitable aniline derivative to develop composite sulfonated poly(ether ether ketone) (SPEEK) membranes and detail evaluation of their physico‐ and electrochemical properties. The hypothesis was high basicity of the aniline derivatives could form good composite membranes with better physicochemical and electrochemical properties. To assess the basicity we measured the zeta potentials of the polymers and correlated them with ion‐exchange capacities, water uptakes, transport numbers, water‐diffusion coefficients, conductivities, and methanol permeabilities. The obtained values of zeta potentials at pH 7 were 6.52, ?14.66, ?25.17, and ?28 for SPEEK/polynaphthalene (PNAPH), SPEEK/polyanisidine (PANIS), SPEEK/polyaniline (PANI), and SPEEK/polyxylindine (PXYL), respectively supports the hypothesis and strongly suggests polyaniline derivative's basicity‐dependent properties. Of the four derivatives (PNAPH, PANIS, PANI, and PXYL), the SPEEK/PXYL composite membrane had the lowest methanol permeability of 1 × 10^?4 cm²/s and highest proton conductivity of 161 mS/cm. These values are far better than the neat SPEEK and SPEEK/PANI composite. The suitability of SPEEK/PXYL can be explained by the high basicity of the PXYL composite membrane, which leads to the formation of effective Debye spheres, meaning that the ionic complex can interact with surrounding hydronium ions and form hydrophilic channels resulting in high proton conductivity and low methanol permeability. These results suggest that SPEEK/PXYL is a highly suitable membrane for methanol fuel cells or other electrochemical applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43978.     

Stable anion exchange membranes derived from fluorinated poly(aryl ethers) with quaternized fluorene units for fuel cell applications

A series of fluorinated poly(aryl ethers) containing benzyltrimethyl quaternary ammonium functionalized fluorene units (QPFAE) are synthesized via condensation polymerization, chloromethylation, and quaternization. Ionomer structure and the ion exchange capacity are confirmed by ¹H‐nuclear magnetic resonance spectroscopy. Other characterization techniques such as Fourier transform infrared spectroscopy, atomic force microscopy, thermogravimetric analysis, gel permeation chromatography, electrochemical impedance spectroscopy, Fenton, water‐swelling, and hydrolytic aging tests are used to evaluate the physicochemical properties of the as‐prepared QPFAE membranes. For the QPFAE membranes with ion exchange capacity of 0.95–1.94 mmol/g, they displayed low water uptake and methanol permeability (4.59–26.1 × 10⁻⁸ cm²/s at 25 °C), fairly good dimensional stability, high mechanical toughness, as well as fine thermal‐oxidative‐hydrolytic stability and ion conductivity at least 10 mS/cm. The membranes also showed clear hydrophilic/hydrophobic phase‐separation morphology. Furthermore, the QPFAE membranes could endure harsh basic conditions (1–4 mol/L NaOH solution) at 60 and 80 °C at least 240 h, keeping rather high mechanical toughness and ion conduction capability during the aging test. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46301.     

The influence of poly(3,4-ethylenedioxythiophene) modification on the transport properties and fuel cell performance of Nafion-117 membranes

Nafion-117/PEDOT composite membranes were synthesized by in situ chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) using ammonium persulfate as an oxidant. The polymerization of EDOT in Nafion membranes for various EDOT/oxidant treatment sequences was studied for the first time. PEDOT introduction leads to a slight decrease in both the ion-exchange capacity and water uptake of the composite membranes, as well as to an increase in cationic transport. Membranes initially treated with an oxidant exhibit better conductivity and lower hydrogen permeability. The effect of both modification of Nafion-117 membranes by PEDOT and hot-pressing of hydrogen-oxygen membrane-electrode assemblies (MEAs) on the performance of proton-exchange membrane fuel cells was studied. The maximum power density of the fabricated MEAs increases 1.5-fold: from 510 (for a pristine Nafion-117 membrane) to 810 mW cm⁻² (for a membrane modified by PEDOT). The current density at a voltage of 0.4 V reaches 1248 and 2246 mA cm⁻², respectively.     

Montmorillonite‐reinforced sulfonated poly(phthalazinone ether sulfone ketone) nanocomposite proton exchange membranes for direct methanol fuel cells

To produce a composite membrane with high conductivity and low permeability, SPPESK with a degree of sulfonation of 101% was carefully selected for the preparation of montmorillonite (MMT)‐reinforced SPPESK using solution intercalation. The fundamental characteristics such as water uptake, swelling ratio, proton conductivity, methanol permeability, and mechanical properties of the composite membranes were studied. Water uptake is improved when organic MMT (OMMT) loading increase. The composite membranes with CTAB‐MMT loading of 4–0.5% show 0.143–0.150 S cm^?1 proton conductivity at 80°C, which approaches the value of Nafion112. In addition, methanol permeability was decreased to 6.29 × 10^?8 cm² s^?1 by the addition of 6 wt % OMMT. As a result, the SPPESK‐MMT composite membrane is a good candidate for use in direct methanol fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39852.     

Highly selective sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene)/poly(ether sulfone) blend proton exchange membranes for direct methanol fuel cells

Proton exchange membranes (PEMs) based on blends of poly(ether sulfone) (PES) and sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene) (sPVdF‐co‐HFP) were prepared successfully. Fabricated blend membranes showed favorable PEM characteristics such as reduced methanol permeability, high selectivity, and improved mechanical integrity. Additionally, these membranes afford comparable proton conductivity, good oxidative stability, moderate ion exchange capacity, and reasonable water uptake. To appraise PEM performance, blend membranes were characterized using techniques such as Fourier transform infrared spectroscopy, AC impedance spectroscopy; atomic force microscopy, and thermogravimetry. Addition of hydrophobic PES confines the swelling of the PEM and increases the ultimate tensile strength of the membrane. Proton conductivities of the blend membranes are about 10^?3 S cm^?1. Methanol permeability of 1.22 × 10^?7cm² s^?1 exhibited by the sPVdF‐co‐HFP/PES10 blend membrane is much lower than that of Nafion‐117. AFM studies divulged that the sPVdF‐co‐HFP/PES blend membranes have nodule like structure, which confirms the presence of hydrophilic domain. The observed results demonstrated that the sPVdF‐co‐HFP/PES blend membranes have promise for possible usage as a PEM in direct methanol fuel cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43907.     

Solution‐blown SPEEK/POSS nanofiber–nafion hybrid composite membranes for direct methanol fuel cells

This study aims to develop novel hybrid composite membranes (NHMs) by impregnating Nafion solution into the porous sulfonated poly(ether ether ketone)/polyhedral oligomeric silsesquioxanes (SPEEK/POSS) nanofibers (NFs). The composite membrane was prepared by solution blowing of a mixture of SPEEK/POSS solution. The characteristics of the SPEEK/POSS NFs and the NHMs, including morphology, thermal stability, and performance of membrane as PEMs, were investigated. The performance of NHMs was compared with that of Nafion117 and SPEEK/Nafion composite membranes. Results showed that the introduction of POSS improved the proton conductivity, water swelling, and methanol permeability of membranes. A maximum proton conductivity of 0.163 S cm^?1 was obtained when the POSS content was 6 wt % at 80°C, which was higher than that of Nafion117 and SPEEK/Nafion. NHMs could be used as proton exchange membranes (PEMs) for fuel cell applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42843.     

Effect of thermal crosslinking on the properties of sulfonated poly(phenylene sulfone)s as proton conductive membranes

The synthesis and characterization of crosslinked aromatic polymer membranes with high ion exchange capacity (IEC) values are reported. Through aromatic nucleophilic substitution polycondensation and the subsequent sulfonation reaction, the highly sulfonated polymers SPPSU‐2S and SPPSU‐4S with high molecular weight (M_n = 138–145 kDa, M_w = 200–279 kDa) and well‐defined structures were synthesized. By solution casting and thermal annealing treatment, flexible crosslinked membranes with high solvent insolubility were obtained. The membranes exhibited mechanical and chemical stability as confirmed by dynamic mechanical analysis (DMA) and conductivity measurement. The crosslinked SPPSU‐4S membrane with IEC = 3.20 meq/g showed the highest proton conductivity of 0.163 S/cm at 120 °C, 90% RH, and improved thermal stability compared with its precursor (uncrosslinked) membrane. The results show that simple annealing method could improve significantly membranes properties of highly sulfonated aromatic polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44218.     

Durability and performance of polystyrene‐b‐poly(vinylbenzyl trimethylammonium) diblock copolymer and equivalent blend anion exchange membranes

Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study, a polystyrene‐b‐poly(vinylbenzyl trimethylammonium) diblock copolymer was evaluated as potential AEM and compared with the equivalent homopolymer blend. The diblock had a 92% conversion of reactive sites with an IEC of 1.72 ± 0.05 mmol g^?1, while the blend had a 43% conversion for an IEC of 0.80 ± 0.03 mmol g^?1. At 50°C and 95% relative humidity, the chloride conductivity of the diblock was higher, 24–33 mS cm^?1, compared with the blend, 1–6 mS cm^?1. The diblock displayed phase separation on the length scale of 100 nm, while the blend displayed microphase separation (～10 μm). Mechanical characterization of films from 40 to 90 microns thick found that elasticity and elongation decreased with the addition of cations to the films. At humidified conditions, water acted as a plasticizer to increase film elasticity and elongation. While the polystyrene‐based diblock displayed sufficient ionic conductivity, the films' mechanical properties require improvement, i.e., greater elasticity and strength, before use in fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41596.     

Branched poly(biphenylene-co-sulfone)ether ion exchange membranes containing perfluorocyclobutane groups for fuel cell applications

A series of branched poly(biphenylene-co-sulfone) ion exchange membranes containing perfluorocyclobutane groups were prepared for fuel cells. Two bifunctional trifluorovinyloxy-terminated monomers (sulfonable 4,4′-bis(trifluorovinyloxy)biphenyl and insulfonable 4,4′-sulfonyl-bis(trifluorovinyloxy)biphenyl) and a trifunctional trifluorovinyloxy-terminated branching agent (1,1,1-tris(4′-trifluorovinyloxyphenyl)ethane) were synthesized and terpolymerized via thermal [2π + 2π] cyclodimerization to obtain partially fluorinated and branched polymers containing 0–5 mol% of the branching agent. They were then postsulfonated by chlorosulfonic acid at room temperature, cast as membranes, and characterized to evaluate their electrochemical properties for fuel cell applications. As the branching agent content was increased, their polydispersity values highly increased, indicating they became highly branched. It was confirmed that higher branching agent content also increased the ion exchange capacity, water uptake, and proton conductivity of the branched ion exchange membranes containing perfluorocyclobutane groups. This indicates that their electrochemical properties can be easily controlled by the degree of branching. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48373.     

Synthesis and properties of sulfonated poly(phosphazene)‐graft‐poly(styrene‐co‐N‐benzylmaleimide) copolymers via atom transfer radical polymerization for proton exchange membrane

A series of sulfonated poly(phosphazene)‐graft‐poly(styrene‐co‐N‐benzylmaleimide) (PP‐g‐PSN) copolymers were prepared via atom transfer radical polymerization (ATRP), followed by regioselective sulfonation which occurred preferentially at the poly(styrene‐co‐N‐benzylmaleimide) sites. The structures of these copolymers were confirmed by Fourier transform infrared (FTIR) spectroscopy, ¹H‐NMR, and ³¹P‐NMR, respectively. The resulting sulfonated PP‐g‐PSN membranes showed high water uptakes (WUs), low water swelling ratios (SWs), low methanol permeability coefficients, and proper proton conductivities. In comparison with non‐grafting sulfonated poly(bis(phenoxy)phosphazene) (SPBPP) membrane previously reported, the present membranes displayed higher proton conductivity, significantly improved the thermal and oxidative stabilities. Transmission electron microscopy (TEM) observation showed clear phase‐separated structures resulting from the difference in polarity between the hydrophobic polyphosphazene backbone and hydrophilic sulfonated poly(styrene‐co‐N‐benzylmaleimide) side chains, indicating effective ionic pathway in these membranes. The results showed that these materials were promising candidate materials for proton exchange membrane (PEM) in direct methanol fuel cell (DMFC) applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42251.     

A synthesis study of phosphonated PSEBS for high temperature proton exchange membrane fuel cells

A series of novel phosphonated proton exchange membranes has been prepared using poly(styrene‐ethylene/butylene‐styrene) block copolymer (PSEBS) as base material. Phosphonic acid functionalization of the polymer was performed by a simple two‐step process, via chloromethylation of PSEBS followed by phosphonation utilizing the Michaels–Arbuzov reaction. The successful phosphonation of the polymers were characterized by NMR and Fourier transform infrared. The phosphonated ester form of the membranes were obtained by solvent evaporation method and hydrolyzed to get a proton conducting membrane. The membrane properties such as ion exchange capacity, water uptake and proton conductivity at various temperatures were examined for their suitability to be utilized as a high temperature polymer electrolyte. Additionally, the morphology, thermal, and mechanical properties of the synthesized membranes were investigated, using scanning electron microscope, thermogravimetric analysis, and tensile test, respectively. The effective (anhydrous) proton conductivity was studied with respect to various degrees of functionalization. From the studies, the membranes were found to have a comparatively good conductivity and one of the membranes reached the maximum value of 5.81 mS/cm² at 140 °C as measured by impedance analyzer. It was found that the synthesized membranes were mechanically durable, chemically, and thermally stable. Hence, the synthesized phosphonated membranes could be a promising candidate for high temperature polymer electrolyte fuel cell applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45954.     

Modification of SPPESK proton exchange membranes through layer‐by‐layer self‐assembly

Sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) composite membranes are fabricated through electrostatic layer‐by‐layer (LbL) self‐assembly method with chitosan (CS) and phosphotungstic acid (PWA) to enhance the proton conductivity and stability. The results demonstrate that LbL self‐assembly has different effects on the SPPESK membrane substrates with different sulfonation degrees (DSs). It elevates proton conductivity of the SPPESK membrane of lower DS and enhances swelling stability of the SPPESK membrane of higher DS. For instance, at 80°C, proton conductivity of the SPPESK0.74/(CS/PWA)₁ membrane (lower DS) increases by 16%–96.49 mS cm^?1, and swelling ratio of the SPPESK1.01/(CS/PWA)₃ membrane (higher DS) decreases from 58 to 29%. Attribute to the electrostatic interaction and ion cross‐linking networks, permeability of the SPPESK0.74/(CS/PWA)₃ membrane and the SPPESK1.01/(CS/PWA)₅ membrane are reduced by 45 and 30%, respectively. The results indicate that the LbL self‐assembly has broadened the available DS range for fuel cell applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42867.     

Nanostructured membrane electrode assemblies from layer‐by‐layer composite/catalyst containing membranes and their fuel cell performances

In this study, two approaches are compared to develop nanostructured membrane electrode assemblies (MEA) using layer‐by‐layer (lbl) technique. The first is based on the direct deposition of polyallylamine hydrochloride (PAH) and sulfonated polyaniline (sPAni) on Nafion support to prepare lbl composite membrane. In the second approach, sPAni is coated on the support in the presence of platinum (Pt) salt, Nafion solution and Vulcan for obtaining catalyst containing membranes (CCMs). SEM and UV–vis analysis show that the multilayers are deposited on both sides of Nafion successfully. Although H₂/O₂ single cell performances of acid doped lbl composite membrane based MEA are found to be at the range of 126 and 160 mW cm^?2 depending on the number of deposited layers, the cell performance of MEA obtained from catalyst containing lbl self‐assembled thin membrane (PAH/sPAni‐H⁺)_10‐Pt is found to be 360 mW cm^?2 with a Pt utilization of 720 mW mgPt^?1. This performance is 82% higher as compared to original Nafion^®117 based MEA (198 mW cm^?2). From the cell performance evaluations for different structured MEAs, it is mainly found out that the use of lbl CCMs instead of composite membranes and fabrication of thinner electrolytes result in a higher H₂/O₂ cell activity due to significant reduction in ohmic resistivity. Also, it is observed that the use of sPAni slightly improves the cell performance due to an increased probability of the triple phase contact and it can lead to superior physicochemical properties such as conductivity and thermal stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40314.     

Vinyl‐addition type norbornene copolymers containing flexible spacers and sulfonated pendant groups for proton exchange membranes

Novel sulfonated poly(2‐butoxymethylenenorbornene‐co‐2‐(6‐phenoxy‐hexyloxymethylene)‐5‐norbornene [sP(BN/PhHN)] were prepared successfully through vinyl‐addition type polymerization and then sulfonated with concentrated sulfuric acid (98%) as sulfonating agent in a component solvent. The sP(BN/PhHN)‐40 with the maximal degree of sulfonation of 40% can be obtained by controlling the sulfonating reaction time from 8 to 20 h, and a proton conductivity of 3.35 × 10^?3 S/cm was achieved at 70°C. The methanol permeabilities of these membranes were in the range from 0.26 to 6.58 × 10^?7 cm²/s, which were remarkably lower than Nafion (2.36 × 10^?6 cm²/s). TEM analysis revealed that these side‐chain type membranes have a microphase separated structure composed of hydrophilic side‐chain domains and hydrophobic polynorbornene main chain domains. Sulfonated polynorbornene containing soft spacers displayed better properties, such as lower water uptake, high thermal properties, mechanical properties, and low methanol permeability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Quaternized poly(2.6 dimethyl‐1.4 phenylene oxide)/polysulfone blend composite membrane doped with ZnO‐nanoparticles for alkaline fuel cells

A series of quaternized poly(2.6 dimethyl‐1.4 phenylene oxide)/polysulfone (QPPO/PSF) blend anion exchange membrane (AEM) were successfully fabricated and characterized for alkaline fuel cell application. Zinc oxide (ZnO) nanoparticles were introduced in the polymer matrix to enhance the intrinsic properties of the AEM. To confirm successful fabrication, Fourier‐transform infrared spectroscopy and nuclear magnetic resonance (¹H‐NMR) were used. The membrane properties were enhanced by the addition of ZnO nanoparticles. The addition of ZnO nanoparticles resulted to a higher ion exchange capacity (IEC) of 3.72 mmol g^?1, increase of ion conductivity (IC) up to 52.34 mS cm^?1 at 80 °C, enhancement of water uptake, and reduced methanol permeability. The QPPO/PSF/2% ZnO composite retained over 80% of its initial IC at room temperature and also retained over 50% of its initial IC at 80 °C when evaluated for alkaline stability. The maximum power output reached for the membrane electrode assembly constructed with QPPO/PSF/2%ZnO was 69 mW cm^?2 at room temperature, which is about three times more than the parent QPPO membrane. The above results indicate that QPPO/PSF/ZnO is a good candidate as an AEM for fuel cell application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45959.     

A new sulfonated poly(ether sulfone) hybrid with low humidity dependence for high‐temperature proton exchange membrane fuel cell applications

A new sulfonated poly(ether sulfone) (PES) hybrid with low humidity dependence was prepared based on a new synthesized PES and Udel as a commercial PES. The PES was synthesized based on a pyridine containing diol which is able to change between pyridine and pyridinium salt forms during the cell performance (acidic condition) and facilitate proton transfer. The presence of nitrogen group increases inter and intramolecular interactions in the membrane and enhance proton hopping mechanism. Thermogravimetrical analysis of PES hybrid shows good thermal stability. Proton conductivity measurements were evaluated on a fuel cell test station, showing that the membrane has better performance under lower humidity (relative humidity = 60%) compare to the fully hydrated condition (relative humidity = 100%). The results reveal that proton transfer might be mainly accomplished through proton hopping mechanism at higher temperatures. The membrane also shows significant proton conductivity at 120 °C (about 6.6 mS cm^?1 at RH = 30%). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45342.