Sulfonated poly(ether sulfone)/phosphotungstic acid/attapulgite composite membranes for direct methanol fuel cells

Novel composite sulfonated poly(ether sulfone)(SPES)/phosphotungstic acid (PWA)/attapulgite (AT) membranes were investigated for direct methanol fuel cells (DMFCs). Physical–chemical properties of the composite membranes were characterized by FTIR, DSC, TGA, SEM‐EDX, water uptake, tensile test, proton conductivity, and methanol permeability. Compared with a pure SPES membrane, PWA, and AT doping in the membrane led to a higher thermal stability and glass transition temperature (T_g) as revealed by TGA and DSC. Tensile test indicated that lower AT content (3%) in the composite can significantly increase the tensile strength, while higher AT loading demonstrated a smaller contribution on strength. Proper PWA and AT loadings in the composite membranes can increase the proton conductivity and lower the methanol cross‐over. The proton conductivity of the SPES‐P‐A 10% composite membrane reached 60% of the Nafion 112 membrane conductivity at room temperature while the methanol permeability was only one‐fourth of that of Nafion 112 membrane. This excellent performances of SPES/PWA/AT composite membranes could indicate a potential feasibility as a promising electrolyte for DMFC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sulfonated poly(ether sulfone)/silica composite membranes for direct methanol fuel cells

A series of sulfonated poly(ether sulfone) (SPES)/silica composite membranes were prepared by sol–gel method using tetraethylorthosilicate (TEOS) hydrolysis. Physico–chemical properties of the composite membranes were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscope–energy dispersive X‐ray (SEM–EDX), and water uptake. Compared to a pure SPES membrane, SiO₂ doping in the membranes led to a higher thermal stability and water uptake. SEM–EDX indicated that SiO₂ particles were uniformly embedded throughout the SPES matrix. Proper silica loadings (below 5 wt %) in the composite membranes helped to inhibit methanol permeation. The permeability coefficient of the composite membrane with 5 wt % SiO₂ was 1.06 × 10^?7 cm²/s, which was lower than that of the SPES and just one tenth of that of Nafion® 112. Although proton conductivity of the composite membranes decreased with increasing silica content, the selectivity (the ratio of proton conductivity and methanol permeability) of the composite membrane with 5 wt % silica loading was higher than that of the SPES and Nafion® 112 membrane. This excellent selectivity of SPES/SiO₂ composite membranes could indicate a potential feasibility as a promising electrolyte for direct methanol fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A modified poly(aryle ether ketone sulfone) proton exchange membrane with in situ polymerized polypyrrole for the direct methanol fuel cells

Bone tissue interfacial scaffolds, which encourage cell growth, are critical determinants for clinical success after implant surgery. Over the years, a number of resorbable configurations have emerged for bone cell support and growth, but only a few have demonstrated clinical efficacy. Polymer coatings produced by electrospinning are regarded as very promising bone interfaces because of the ultrathin‐scaled dimensions of its physical structure. In this study, the morphology, composition, thermal properties, and cell growth viability of a number of polylactide‐based systems containing different binary and ternary formulations of this biomaterial with collagen and commercial hydroxyapatite nanoparticles were characterized. The best performance in terms of biocompatibility was obtained for the tricomponent system in which the submicron fibers were further subjected to uniaxial orientation process during formation. The in vitro proliferation of the cells, which harbored on these ultrathin‐structured mats, was examined by means of a metabolic activity indicator and ensured by means of scanning electron microscopy, and cell anchorage was checked by fluorescent optical microscopy. Finally, the optimum tricomponent material was successfully sterilized for the first time by gamma radiation without noticeable losses in cell‐seeding capacity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sulfonated polyether sulfone‐poly(vinylidene fluoride) blend membrane for DMFC applications

Direct methanol fuel cell (DMFC) proton exchange membranes were prepared by blending poly (vinylidene fluoride) (PVDF) with sulfonated poly(ether sulfone) (SPES). Using a diffusion cell and gas chromatographic technique, the effects of PVDF content on methanol permeability in the blended membranes were investigated. The thermal resistance and proton conductivity of the membranes were also determined by using a thermal gravimetric analysis (TGA) and an impedance analysis technique respectively. The presence of sulfonic acid groups in SPES was confirmed by Fourier transform infrared (FTIR). It was found that the methanol permeability in the blended membranes decreased with PVDF content at the expense of proton conductivity. Blended membranes show methanol permeability values much lower than that of Nafion 115, whereas the proton conductivities of the membranes are comparable with that of Nafion. The thermal stability of these blended membranes is above 250°C, which is sufficiently high for use in DMFC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Sulfonated poly(ether ether sulfone) copolymers for proton exchange membrane fuel cells

Novel aromatic sulfonated poly(ether ether sulfone)s (SPEESs) with tert‐butyl groups were synthesized by aromatic nucleophilic polycondensation of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenylsulfone (SDCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS), and tert‐butylhydroquinone (TBHQ). The resulting copolymers showed very good thermal stability and could be cast into tough membranes. The morphology of the membranes was investigated with atomic force microscopy. The proton conductivity of SPEES‐40 membranes increased from 0.062 S/cm at 25°C to 0.083 S/cm at 80°C, which was higher than the 0.077 S/cm of Nafion 117 under the same testing conditions. These copolymers are good candidates to be new polymeric electrolyte materials for proton exchange membrane fuel cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1443–1450, 2007     

聚醚砜/磺化聚醚醚酮共混膜的制备和性能

采用流延法制备了聚醚砜(PES)含量不同的PES/磺化聚醚醚酮(SPEEK)共混膜。PES与SPEEK具有良好的相容性。所制备PES/SPEEK共混膜的含水率、溶胀度和甲醇透过系数均随PES含量的增加而降低。虽然共混膜的质子传导性能有所降低.但阻醇性能和溶胀性能提高,这说明PES/SPEEK共混膜是一种很好的直接甲醇燃料电池用固体高分子电解质膜材料。     

Sulfonated poly(ether sulfone)‐based catalyst binder for a proton‐exchange membrane fuel cell

Sulfonated poly(ether sulfone) copolymer (PES 60) and its partially fluorinated analogue (F‐PES 60) were synthesized via the nucleophilic aromatic polycondensation of commercially available monomers to make a polymer electrolyte membrane and a binding material in the electrodes of a membrane–electrode assembly (MEA). PES 60 and F‐PES 60 showed proton conductivities of 0.091 and 0.094 S/cm, respectively, in water at room temperature. The copolymer was dissolved in the mixture of alcohol and water to get a 1 wt % binder solution. A catalyst slurry was prepared with the copolymer solution and sprayed on the copolymer (PES 60 or F‐PES 60) membrane to obtain a MEA. Both PES 60 and F‐PES 60 based MEAs were fabricated with different amounts of their binder in the electrodes to examine the effect of the copolymer binder in the catalyst layer on the fuel cell performance. The MEA with 2 wt % copolymer binder in the electrodes showed the best fuel cell performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Sulfonated (graphene oxide/poly(ether ketone ether sulfone) (S-GO/S-PEKES) composite proton exchange membrane with high proton conductivity for direct methanol fuel cell

ABSTRACT

Sulfonated poly(ether ketone ether sulfone) (S-PEKES) was successfully prepared to obtain the currently highest degree of sulfonation of 0.744. Sulfonated graphene oxide (S-GO) was incorporated into the S-PEKES matrix to increase sulfonic groups (SO₃H) which significantly improved the proton conductivity, methanol blocking, and mechanical stability. The proton conductivity of the S-GO/S-PEKES composite membrane was enhanced up to 5.93 × 10^?2 S.cm^?1, which was 7 times higher than the commercial Nafion 117. S-GO exhibited additional positive effects namely the blocking of methanol passing through the membrane, leading to lower methanol crossover than Nafion 117 by two orders of magnitude and high mechanical stability.     

Performance of the sulfonated poly ether ether ketone proton exchange membrane modified with sulfonated polystyrene and phosphotungstic acid for microbial fuel cell applications

In this research, the preparation of low cost proton exchange membranes (PEMs) based on sulfonated poly ether ether ketone (SPEEK) for application in the microbial fuel cells (MFCs) is studied. Sulfonated polystyrene (SPS) and phosphotungstic acid (PWA) were employed to improve the performance of PEM through the creation of more proton pathways. At first, the sulfonation of PEEK and polystyrene were performed through two modified methods to obtain uniform and high degree of sulfonation (DS) of the polymers and then, the PEMs were prepared through the solution casting method. Accordingly, the formation of uniform skin layer was confirmed by the SEM micrographs. Blending the aforementioned additives to the SPEEK polymer solution significantly enhanced the proton conductivity, water uptake and durability of the modified membranes. The proton conductivities of SPEEK/SPS and SPEEK/PWA membranes at additive/SPEEK weight ratio of 0.15 were 45.3% and 26.2% higher than that of the commercial Nafion117 membrane, respectively. Moreover, the degradation times for the abovementioned modified membranes were 140 and 350 min which indicated satisfactory oxidation stability. Besides, the aforementioned membranes exhibited two times more water uptake compared to the neat SPEEK membrane. Finally, SPEEK/SPS and SPEEK/PWA membranes produced 68% and 36% higher maximum power in the MFC, compared to the commercial Nafion117 membrane. Therefore, the fabricated PEMs are potentially suitable alternatives to be used in the fuel cell applications.     

含氟磺化聚芳醚酮质子交换膜的制备与性能研究

以六氟双酚A(6FBPA),4,4′-二氟二苯酮(DFBP)和3,3′-二磺酸钠基-4,4′-二氟二苯酮(SDFBP)为单体,调整单体DFBP与SDFBP的摩尔投料比,通过缩合共聚反应合成了一系列离子交换容量不同的含氟磺化聚芳醚酮共聚物(SPEK-6Fs)。采用红外(FT-IR)、核磁共振氢谱(1H-NMR)对共聚物的结构进行了表征,同时对所制备的质子交换膜的吸水率、尺寸稳定性、甲醇透过率、质子电导率及抗氧化性能等进行了一个综合的评价。结果表明:所合成的聚合物具有较高的分子量,可通过溶液浇铸成膜法制备成柔韧、透明的膜,所制备的膜具有良好的尺寸稳定性,在同等测试条件下,具有与杜邦公司Nafion 117膜相当的质子电导率,同时,其甲醇渗透率比Nafion 117膜低1~2个数量级。     

静电层层自组装改性SPPESK/PWA质子交换膜

运用直接掺杂法制备的磺化聚芳醚砜酮/磷钨酸(SPPESK/PWA)复合质子交换膜存在PWA流失严重的问题,影响了膜的正常使用。为了解决这一问题,以壳聚糖(CS)和PWA为聚阴阳离子电解质对,对复合膜进行静电层层(LBL)自组装改性研究,对膜的吸水率、溶胀度、质子传导率等性能进行了表征,并测试了膜中PWA的稳定性。经测定,SPPESK/PWA/(CS/PWA)₂的质子传导率达到154mS/cm(80℃),高于相应的SPPESK膜(118mS/cm)及SPPESK/PWA膜(147mS/cm);SPPESK/PWA/(CS/PWA)₄在80℃水中浸泡30天后,膜的质量损失率由18.45%降为11.81%,电导率损失率由32.20%降为16.77%。结果表明,该方法不仅提高了复合膜的质子传导率,并且有效抑制了PWA的流失。     

Synthesis and characterization of homogeneously sulfonated poly(ether ether ketone) membranes: Effect of casting solvent

Poly(ether ether ketone) (PEEK) was homogeneously sulfonated to have various degrees of sulfonation from 48 to 83%. The sulfonated PEEK (sPEEK) membranes were prepared by a solvent casting method using a few solvents such as N,N‐dimethyl formamide, N,N‐dimethyl acetamide, and 1‐methyl‐2‐pyrrolidinone. The effect of casting solvent on the membrane morphology and properties was investigated. The sulfonation degree and ion exchange capacity were determined by a back titration method, and the morphology of membrane by SEM. It has been demonstrated that the surface morphology and properties of sPEEK membranes, such as water uptake, methanol permeability, ion conductivity, and mechanical strength, were considerably affected by the type of solvent, where the DMAC‐sPEEK system showed the best performance in the polymer electrolyte membrane application for DMFC. This solvent effect on the membrane morphology and properties was caused by interaction strength (hydrogen bonding) between polymer and solvent. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Proton exchange composite membranes from blends of brominated and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

New composite proton exchange membrane was prepared by mixing a 1‐methyl‐2‐pyrrolidone (NMP) solution of sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO) in sodium form and brominated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (BPPO) for hydrophilic‐hydrophobic balance, then casting the solution as a thin film, evaporating the solvent, and treating the membrane with aqueous hydrochloric acid. The resulting membranes were subsequently characterized using FTIR‐ATR, SEM‐EDXA, and TGA instrumentation as well as measurements of basic properties such as ion exchange capacity (IEC), water uptake, proton conductivity, methanol permeability, and single cell performance. Water uptake, IEC, proton conductivity, and methanol permeability all increased with a corresponding increase of SPPO content. By properly compromising the conductivity and methanol permeability, membranes with 60–80 wt % SPPO content exhibited comparable proton conductivity to that of Nafion^® 117, with only half the methanol permeability, thereby demonstrating higher single cell performance. The membranes developed in this study could thus be a suitable candidate electrolyte for proton exchange membrane fuel cells (PEMFCs). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) blends for proton exchange membrane

Poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) (PVdF/SPPESK) blend membranes are successfully prepared by solution blending method for novel proton exchange membrane (PEM). PVdF crystallinity, FTIR‐ATR spectroscopy, thermal stability, morphology, water uptake, dimension stability, and proton conductivity are investigated on PVdF/SPPESK blends with different PVdF contents. XRD and DSC analysis reveal that the PVdF crystallinity in the blends depends on PVdF content. The FTIR‐ATR spectra indicate that SPPESK remains proton‐conducting function in the blends due to the intactness of ? SO₃H group. Thermal analysis results show a very high thermal stability (T_d1 = 246–261°C) of the blends. PVdF crystallinity and morphology study demonstrate that with lower PVdF content, PVdF are very compatible with SPPESK. Also, with lower PVdF content, PVdF/SPPESK blends possess high water uptake, e.g., P/S 10/90 and P/S 15/85 have water uptake of 135 and 99% at 95°C, respectively. The blend membranes also have good dimension stability because the swelling ratios are at a fairly low level (e.g., 8–22%, 80°C). PVdF/SPPESK blends with low PVdF content exhibit very high proton conductivity, e.g., at 80°C, P/S 15/85 and P/S 10/90 reach 2.6 × 10^?2 and 3.6 × 10^?2 S cm^?1, respectively, which are close to or even higher than that (3.4 × 10^?2 S cm^?1) of Nafion115 under the same test condition. All above properties indicate that the PVdF/SPPESK blend membranes (particularly, with 10–20% of PVdF content) are very promising for use in PEM field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Partially sulfonated poly(arylene ether sulfone)-b-polybutadiene for proton exchange membrane

A novel block copolymer based on poly(arylene ether sulfone)-b-polybutadiene (SPAES-b-PB) was synthesized and its flexible segment was sulfonated by electrophilic addition reaction with acetyl sulfate. This could be a new approach to prepare suitable alternative proton exchange membranes to Nafion^®. Only a single glass transition temperature (T_g) of copolymer measured by differential scanning calorimeter (DSC) indicated good compatibility between PAES block and PB block. A tough and transparent membrane based on SPAES-b-PB exhibited higher proton conductivity (0.0302 S/cm at 25 °C and 100% relative humidity) even with relatively low ion exchange capacity (IEC) of 0.624 mmol/g compared to other sulfonated block copolymer membranes such as sulfonated polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene (SSEBS), sulfonated poly(styrene-isobutylene-styrene) (S-SIBS), sulfonated hydrogenated poly-butadiene-styrene copolymer (HPBS-SH) as a result of selected sulfonation of the flexible segments facilitating sulfonated groups to aggregate to form ion-rich channels.     

Composite Proton Exchange Membranes of Sulfonated Poly(ether ketone ether sulfone) (S-PEKES) and Molecular Sieve With High Mechanical Strength for Direct Methanol Fuel Cell

Composite proton exchange membranes are prepared by solvent casting via the incorporation of molecular sieves 3A, 4A, and 5A into the sulfonated poly(ether ketone ether sulfone) (S-PEKES) at the sulfonation degree of 0.66, with varying the ratio at of 3%, 6%, 9%, and 12% v/v. The influences of type and amount of the molecular sieves on the proton conductivity, methanol permeability, structural, thermal, and mechanical stabilities of the membranes are investigated. The composite membranes are characterized by FTIR, TGA, LCR meter, and GC techniques. All properties of the composite membrane are compared with the pristine S-PEKES and Nafion 117 membrane.     

Sulfonated poly(ether ether ketone) membranes crosslinked with sulfonic acid containing benzoxazine monomer as proton exchange membranes

The incorporation of benzoxazine (Ba) or sulfonic acid containing benzoxazine (SBa) as a crosslinking agent in SPEEK proton exchange membrane (PEM) can substantially improve the SPEEK membrane performance. The SPEEK-SBa membranes give higher effective selectivity than corresponding SPEEK-Ba membranes under close crosslinker loading and thus are more suitable to be used in direct methanol fuel cells. The best achieved SPEEK-SBa composition (SBa40) gives reasonable proton conductivity (0.91 × 10⁻² S cm⁻¹) but significantly lower methanol permeability (6.5 × 10⁻⁸ S² cm⁻¹). The achieved effective selectivity (Φ = SPEEK-SBa40: 14.0 × 10⁴ S s cm⁻³) is substantially higher than the plain SPEEK (Φ = 7.24 × 10⁴ S s cm⁻³) which has great potential for practical applications in DMFCs.     

Study of high-temperature proton exchange membrane through one-step encapsulation of ionic liquid in sulfonated poly(ether ether ketone)

The proton exchange membrane (PEM) is the core component of a high-performance proton exchange membrane fuel cell (PEMFC). Since the traditional PEM has the disadvantages of poor cell performance and high cost, a new kind of PEM with good proton conductivity, low cost and simple preparation should be explored. In this paper, several different binary hybrid membranes were successfully prepared through one-step encapsulation of different ionic liquids (ILs) in sulfonated poly(ether ether ketone) (SPEEK). The prepared membranes were characterized by scanning electron microscope (SEM), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), proton conductivity measurements and dynamic mechanical analysis (DMA). SEM images showed that ILs were fully doped into SPEEK. FT-IR and XPS proved that SPEEK and IL formed a new chemical bond combined with intermolecular hydrogen bonds. The TG results showed that the binary hybrid membranes could maintain stability even at 300°C. The water uptake and swelling ratio showed that the water absorption capacity of the binary composite membrane played a vital role in improving proton conductivity. The proton conductivity study showed that ILs doping also helped to improve the proton conductivity of the SPEEK membrane. When the doping amount of IL was maintained at 30 wt.%, it has the highest proton conductivity, 25 mS cm⁻¹ at 120°C. It was proved that anhydrous hybrid membrane tetraphenyl imidazole sulfate/SPEEK ([IM2][H₂PO₄]/SPEEK) could be used in PEMFC at medium temperature.     

Proton conducting membranes based on sulfonated poly(ether ether ketone)/TiO2 nanocomposites for a direct methanol fuel cell

This paper presents an evaluation of the effects of titanium dioxide nanoparticles in sulfonated poly(ether ether ketone) (SPEEK) with a sulfonation degree of 57%. A series of inorganic/organic hybrid membranes was prepared with a systematic variation of titanium dioxide nanoparticle content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increasing the inorganic oxide content leads to a decrease of methanol permeability. In terms of morphology, the membranes are homogeneous and exhibit good adhesion between inorganic domains and the polymer matrix. The proton conductivity and fuel cell performances of the nanocomposite membranes showed very good prospective in direct methanol fuel cell usages. The properties of the composite membranes are compared with those of standard Nafion membranes. Copyright © 2006 Society of Chemical Industry     

磷酸化二氧化硅填充磺化聚醚醚酮质子交换膜的制备及表征

制备了两种磷酸化改性的介孔二氧化硅亚微米球形颗粒,分别为仅外表面接枝磷酸根基团的颗粒(PMPS-Ⅰ)和内外表面均接枝磷酸根基团的颗粒(PMPS-Ⅱ)。颗粒具有均一的尺寸和规则排布的六面体一维贯通孔道。将制备的二氧化硅颗粒与磺化聚醚醚酮(SPEEK)溶液共混制备杂化膜。与填充PMPS-Ⅰ的杂化膜相比,填充PMPS-Ⅱ的杂化膜显示出较好的质子传导性能。当PMPS-Ⅱ的填充量为5%(质量)时,杂化膜在60℃、100%相对湿度下最高质子传导率为0.241 S·cm^-1。研究结果表明,连续贯通的质子传递通道有助于提高杂化膜的质子传导率。