Synthesis and characterization of sulfonated fluorene-containing poly(arylene ether ketone) for high temperature proton exchange membrane

A novel fluorene-containing poly(arylene ether ketone) were synthesized followed by sulfonating into a series of sulfonated fluorene-containing poly(arylene ether ketone)s using chlorosulfonic acid. The sulfonated polymers were thereafter cast into membranes from their solutions. The properties of the ionic exchange capacity, sulfonation degree, water-uptake, mechanical properties, thermal and oxidative stabilities as well as proton conductivities of the membranes were fully investigated. It was found that their proton conductivities increased continuously with increasing testing temperature up to 130 °C at 100% relative humidity. The membrane exhibited a higher proton conductivity and other comprehensive properties for proton exchange membrane than Nafion-117 at 130 °C under same testing conditions.     

Synthesis of sulfonated poly(fluorenyl ether thioether ketone)s with bulky-block structure and its application in vanadium redox flow battery

High-molecular-weight bulky-block poly(fluorenyl ether thioether ketone)s were successfully synthesized by a two steps one-pot protocol using N,N′-dimethy-S-carbamate masked dithiols for vanadium redox flow battery (VRB) application. The followed sulfonation procedure gave birth to novel sulfonated block poly(fluorenyl ether thioether ketone)s (SPFETKs) with controlled ionic exchange capacities (IEC). Membranes with proton conductivities higher than (IEC > 1.66 mequiv. g⁻¹) or comparable to (IEC < 1.66 mequiv. g⁻¹) that of Nafion117 membrane were achieved. The VO²⁺ permeabilities of SPFETKs membranes were much lower than that of Nafion117 membrane. The thermal properties, mechanical properties, oxidative stability, water uptake, proton conductivity, VO²⁺ permeability and cell performance were investigated in detail.     

Sulfonated poly(arylene ether sulfone) membranes based on biphenol for direct methanol fuel cells

A series of sulfonated poly(arylene ether sulfone) (PAES) were synthesized through direct aromatic nucleophilic substitution polycondensation of 3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (SDCDPS), 4,4-dichlorodiphenylsulfone (DCDPS) and 4,4-biphenol (BP). With increasing sulfonate groups in the polymer, water uptake, ion exchange capacity (IEC) and proton conductivities increased, resulting from enhanced membrane hydrophilicity. The membranes exhibited higher thermal stability up to 300 °C, verified by thermogravimetric analysis (TGA). A maximum proton conductivity of 0.11 S/cm at 50 mol% of sulfonation degree was measured at 30 °C, which is slightly higher than Nafion®117 membrane (0.0908 S/cm). However, the methanol permeability of the PAES membrane was much lower than that of Nafion®117 membrane. As a result, a single cell performance test demonstrated that PAES-BP with 50 mol% sulfonation degree exhibited higher power density than Nafion®117.     

Surface Fluorination of Poly(fluorenyl ether ketone) Ionomers as Proton Exchange Membranes for Fuel Cell Application

A series of sulphonated poly(fluorenyl ether ketone) ionomers were successfully fluorinated by the means of direct surface fluorination. Polymer ionomer samples in two different states (membrane and powder) were treated with F₂ gas which is diluted in N₂ in a special reactor. X‐ray photoelectron spectroscopy (XPS) was used to examine the F/C ratios of the fluorinated materials. The results revealed that the fluorination only occurred on the membrane surface and the fluorination degree increased with increasing F₂ concentration in N₂. The membrane subjected to fluorination shows an obviously enhanced oxidative stability. The endurance in a Fenton's reagent of FSPFEK‐P‐28 is longer than 180 min which is two times longer than that of un‐fluorinated SPFEK. The PEM properties and single fuel cell performances were investigated by comparison of un‐ and fluorinated polymer ionomers. The fluorinated membranes demonstrated an enhanced hydrophobic surface property, increased proton conductivities and better single fuel cell performances. Surface fluorination provides a convenient and useful approach to prepare highly proton conductive membrane with long life‐time PEM fuel cell applications.     

直接甲醇燃料电池用新型质子交换膜的研究

以聚醚醚酮(PEEK)为原料,浓硫酸为磺化剂制备了不同磺化度的磺化聚醚醚酮(SPEEK)膜,以及磺化聚醚醚酮与聚乙烯醇(PVA)、正硅酸乙酯(TEOS)、磷钨酸的复合膜.分别对膜的电导率、阻醇性能和吸水率进行了研究.随着SPEEK膜磺化度的增大,膜的电导率有所提高,然而甲醇渗透系数也增大,膜的机械强度明显降低.SPEEK膜的吸水率低于Nafion 115膜,而PVA膜的吸水率则过高.     

主链组成对低磺化度磺化芳香族聚合物质子交换膜性能的影响

通过改变共聚单体种类,探究主链元素种类对聚合物质子交换膜性能的影响。以3,3'-二磺酸基钠盐-4,4'-二氟二苯砜为磺化单体,4,4'-二氟二苯砜为非磺化单体,4,4'-二羟基二苯醚或4,4'-二巯基二苯硫醚为共聚单体,通过亲核缩聚反应成功可控制备出磺化度分别为30%和50%的磺化聚芳醚砜（SPES）与磺化聚芳硫醚砜（SPTES）。采用流延法制备了两种聚合物的透明坚韧的质子交换膜。研究发现两种聚合物膜均显示出了良好的力学性能以及较为适中的吸水率与溶胀度。两种聚合物质子交换膜的起始分解温度达到250℃,具有良好的热稳定性。随磺化度的升高,两种聚合物膜的吸水率、溶胀率以及质子传导率均升高。由于主链硫较氧原子与苯环的共轭作用更强以及供电子硫原子与吸电子基团的相互作用,SPTES膜较SPES膜表现出更高的玻璃化转变温度（T _g）、更低的溶胀率以及更高质子传导率。其中SPES-50与SPTES-50在80℃、100%RH条件下,质子传导率分别为0.136S/cm与0.142S/cm,表明其作为质子交换膜具有潜在的应用前景。     

Crosslinked Sulfonated Polysulfone-Based Polymer Electrolyte Membranes Induced by Gamma Ray Irradiation

Sulfonated aromatic polymers generally show high swelling at high proton conductivity. This disadvantage makes many of them unfit for proton exchange membrane applications. Crosslinking of the polymer is one way to overcome this problem. In this study, radiation-induced crosslinking was performed on a sulfonated polysulfone membrane, with doses ranging from 2.5 to 25.0 kGy (dose rate: 45 Gy/min) using gamma rays from a ⁶⁰Co source. The pristine sulfonated polysulfones was obtained by mild sulfonation of bisphenol-A-polysulfone with trimethylsilyl chlorosulfonate as sulfonating agent. The proton conductivity of the membranes was characterized by means of electrical impedance spectroscopy techniques. Ion-exchange capacity, degree of sulfonation, water content and chemical stability membrane properties were characterized before and after irradiation. The results show that the mechanical, chemical and thermal stability of the membrane improve after irradiation. The degree of sulfonation and the proton conductivity exhibit a tendency to decrease with increasing irradiation total dose.     

无机杂化倍半硅氧烷／磺化杂萘联苯聚醚酮质子导电复合膜

通过磺化反应制备了一系列不同磺化程度的磺化杂萘联苯聚醚酮（SPPEK）,采用共混法将无机杂化倍半硅氧烷（POSS）掺杂到IEC值为1．60的SPPEK中,通过溶液浇铸制得复合膜。对SPPEK／POSS复合膜进行了FTIR、TGA分析和SEM表观形貌观察。研究了SPPEK／POSS复合膜的吸水性、溶胀度和质子导电性,并与Nation 117进行对比。随着POSS的加入,复合膜的吸水性、溶胀度和氧化稳定性提高。SPPEK／POSS复合膜的室温电导率达到0．75×10^-2S·cm^-1,接近Nafion 117膜相同条件下的电导率（1．08×10^-2S·cm^-1）。随着温度升高,SPPEK／POSS复合膜的电导率逐渐增大。采用不同测试方法分别对复合膜的膜平面方向和厚度方向上的电导率进行了测试,表明在两个方向上的电导率相差较大,SPPEK／POSS复合膜室温下膜平面方向上的电导率达到2．1×10^-2S·cm^-1。     

全钒液流电池用磺化聚芴醚酮质子交换膜的制备及性能

质子交换膜(PEM)作为全钒液流电池(VRFB)的核心组件之一,应当解决成本高昂、合成过程复杂等问题,并具备高质子传导率、低钒离子渗透率、高机械强度和优异化学稳定性等关键性能。本文基于四甲基双酚芴单体通过缩聚反应合成了一系列聚芴醚酮化合物PFEKs,再利用溴代反应将苯甲基功能化为溴甲基,接着通过4-羟基苯磺酸钠的SN₂亲核取代制得了一系列不同离子交换容量的磺化聚芴醚酮聚合物(SPFEKs)。通过溶液浇铸法成膜并酸化,得到一系列新型低成本PEMs。该合成路线的原料来源广泛,价格低廉,不涉及危险的磺化反应,易于工业放大。所得膜都具有良好的机械性能和氧化稳定性,其中SPFEK-40膜具有较高的质子传导率及离子选择性、较低的钒离子渗透率及面电阻,综合性能优异。以SPFEK-40膜组装的VRFB在电流密度为80 mA/cm₂^{时的能量效率}(EE)为88.2%,高于以Nafion 212膜组装的VRFB的84.8%。此外,以SPFEK-40膜组装的VRFB在30次循环后放电容量仅衰减至84.3%,远高于以Nafion 212膜组装的VRFB的66.1%。     

质子交换膜燃料电池用磺化聚醚醚酮膜的研究进展

Nafion膜具有优良的化学稳定性和导电性能,但是它成本高,高温下几乎不导电。本文回顾了Nafion替代膜之一——磺化聚醚醚酮（SPEEK）膜及SPEEK/离子液体（IL）复合膜的研究进展。介绍了SPEEK制备的两种方法：直接磺化法和磺化单体聚合法,其中直接磺化法工艺简单,但磺化度（DS）≤1.0,反应较难控制;磺化单体聚合法DS可控,但工艺复杂,原料有毒。简述了温度、反应时间、原料配比、磺化单体种类、制膜工艺及溶剂对SPEEK膜性能的影响：直接磺化法中DS与温度成负相关,与反应时间成正相关,与原料配比关系不大;磺化单体聚合法中DS受磺化单体的种类和氟酮与磺化氟酮的比例影响较大。着重介绍了SPEEK/咪唑离子液体复合膜和SPEEK/季铵盐离子液体复合膜的研究现状及应用于质子交换膜燃料电池（PEMFC）时存在的问题。最后对SPEEK/IL复合膜未来的研究方向进行了展望,即解决燃料电池运行过程中复合膜中离子液体流失及与Pt基催化剂相容性等关键问题,以提高PEMFC的性能。     

Incorporating of layered double hydroxide/sepiolite to improve the performance of sulfonated poly(ether ether ketone) composite membranes for proton exchange membrane fuel cells

Sulfonated poly(ether ether ketone) (SPEEK) with a low sulfonation degree was blended using nanofiller layered double hydroxide (LDH, Mg₂AlCl)/sepiolite nanostructured material as additive to use as an electrolyte membrane for fuel cell application. Characterization assessments, that is, mechanical stability, thermal gravimetric analysis, ion exchange capability, swelling properties, water uptake capacities, electrochemical impedance spectroscopy analysis, and Fourier transform infrared spectroscopy of the composite membranes were conducted. The presence of LDH/sepiolite nanoarchitectured material within SPEEK was found to have the highest water retention and proton conductivity value at high temperature rather than LDH/SPEEK and pristine SPEEK membranes.     

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.     

Partially Sulfonated Poly(1,4‐phenylene ether‐ether‐sulfone) and Poly(vinylidene fluoride) Blend Membranes for Fuel Cells

Blend membranes based on high conductive sulfonated poly(1,4‐phenylene ether‐ether‐sulfone) (SPEES) and poly(vinylidene fluoride) (PVDF) having excellent chemical stability were prepared and characterized for direct methanol fuel cells. The effects of PVDF content on the proton conductivity, water uptake, and chemical stability of SPEES/PVDF blend membranes were investigated. The morphology, miscibility, thermal, and mechanical properties of blend membranes were also studied by means of scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) measurements. The blend membrane containing 90 wt.% SPEES (degree of sulfonation – DS = 72%) and 10 wt.% PVDF (M_w = 180,000) exhibits optimum properties among various SPEES72/PVDF membranes. Addition of PVDF enhanced resistance of the SPEES membrane against peroxide radicals and methanol significantly without deterioration of its proton conductivity. It's proton conductivity at 80 °C and 100% relative humidity is higher than Nafion 115 while it's methanol permeability is only half of that of Nafion 115 at 80 °C. The direct methanol fuel cell performance of the SPEES membranes was better than that of Nafion 115 membrane at 80 °C.     

磺化聚醚醚酮的合成及其性能表征

采用浓硫酸作为磺化剂,利用两种不同分子量的聚醚醚酮(PEEK)制备了具有不同磺化度的磺化聚醚醚酮(SPEEK)膜,用FTIR 和DSC对SPEEK进行了表征,通过质子交换容量(IEC)对磺化度进行了测定,并对SPEEK膜的质子导电性能进行了研究.结果表明,质子交换容量(IEC)与磺化度均随着反应时间的延长而增大,吸水率也随磺化度的增加而增大.     

Polymer electrolyte membranes from fluorinated polyisoprene-block-sulfonated polystyrene: Membrane structure and transport properties

With a view to optimizing morphology and ultimately properties, membranes have been cast from relatively inexpensive block copolymer ionomers of fluorinated polyisoprene-block-sulfonated polystyrene (FISS) with various sulfonation levels, in both the acid form and the cesium neutralized form. The morphology of these membranes was characterized by transmission electron microscopy and ultra-small angle X-ray scattering, as well as water uptake, proton conductivity and methanol permeability within the temperature range from 20 to 60 °C. Random phase separated morphologies were obtained for all samples except the cesium sample with 50 mol% sulfonation. The transport properties increased with increasing degree of sulfonation and temperature for all samples. The acid form samples absorbed more water than the cesium samples with a maximum swelling of 595% recorded at 60 °C for the acid sample having 50 mol% sulfonation. Methanol permeability for the latter sample was more than an order of magnitude less than for Nafion 112 but so was the proton conductivity within the plane of the membrane at 20 °C. Across the plane of the membrane this sample had half the conductivity of Nafion 112 at 60 °C.     

DMFCs用磺化聚醚醚酮/磺化酚酞型聚醚砜共混质子交换膜

A sulfonated poly(ether ether ketone) (SPEEK) membrane with fairly high degree of sulfonation (DS) swells excessively and even dissolves at high temperature. To solve these problems, sulfonated phenolphthalein poly(ether sulfone) (SPES-C, DS 53.7%) is blended with the SPEEK matrix (DS 55.1%, 61.7%) to prepare SPEEK/SPES-C blend membrane. The decrease in swelling degree and methanol permeability of the membrane is dose-dependent. Pure SPEEK (DS 61.7%) membrane dissolves completely in water at 70ºC, whereas the swelling degree of the SPEEK (DS 61.7%)/SPES-C (40%, by mass) membrane is 29.7% at 80ºC. From room temperature to 80ºC, the methanol permeability of all SPEEK (DS 55.1%)/SPES-C blend membranes is about one order of magnitude lower than that of Nafion®115. At higher temperature, the addition of SPES-C polymer increases the dimensional stability and greater proton conductivity can be achieved. The SPEEK (DS 55.1%)/SPES-C (40%, by mass) membrane can withstand temperatures up to 150ºC. The proton conductivity of SPEEK (DS 55.1%)/SPES-C (30%, by mass) membrane approaches 0.16 S&#8226;cm－1, matching that of Nafion&#61650;115 at 140ºC and 100% RH, while pure SPEEK (DS 55.1%) membrane dissolves at 90ºC. The SPEEK/SPES-C blend membranes are promising for use in direct methanol fuel cells because of their good dimensional stability, high proton conductivity, and low methanol permeability.     

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.     

硫酸化SnO2/SPPESK复合质子交换膜的制备及燃料电池性能

非氟聚合物磺化聚芳醚砜酮（SPPESK）具有甲醇渗透率低、化学、热稳定性高等优点,但其高的电导率需通过提高磺化度获得,导致膜因过度溶胀而失去尺寸稳定性。添加无机纳米颗粒可以有效提高膜性能,但因其表面缺少功能化基团,导致颗粒有机相容性差,阻醇性能和质子传导率不易同时提高。硫酸化改性的纳米颗粒因其表面具有酸性位点和硫酸基团,能够有效克服这一问题。本文制备表面硫酸化改性的SnO₂（SSnO₂）纳米颗粒并引入SPPESK基质制备有机无机复合质子交换膜。当SSnO₂含量不大于7.5%时,纳米颗粒具有良好的有机相容性,可均匀分散于聚合物基质。SSnO₂含量为7.5%时,80℃下复合膜吸水率（19.6%）比SPPESK原膜提高19%,接近Nafion115。颗粒诱导膜内离子簇的聚集扩大,降低了质子的传导阻力,质子传导率分别比SPPESK原膜和Nafion115膜提高48%和30%。同时,纳米颗粒增大了甲醇传递空间位阻,甲醇渗透率较SPPESK原膜和Nafion115膜分别降低46%和71%。直接甲醇燃料电池0.5V处功率密度分别比SPPESK原膜和Nafion115膜高205%和50%。     

Multiblock sulfonated poly(arylene ether sulfone)s with fluorenyl hydrophilic moieties for PEMFC applications

Multiblock sulfonated poly(arylene ether sulfone) (MB-SPAES) ionomers containing fluorenyl hydrophilic moieties were synthesized and converted into proton exchange membranes (PEMs) through solution casting, as well as other two types of MB-SPAES membranes containing hydrophilic biphenyl and hexafluoroisopropyl diphenyl moieties for the comparison. Chemical structures of the MB-SPAES ionomers were confirmed by ¹H NMR spectrometer. Fundamental physical properties were characterized based on the ionic group content, the hydrophilic/hydrophobic block structure and length, including ion exchange capacity (IEC), water uptake, size change, mechanical property, proton conductivity, hydrolytic stability and fuel cell performance. All the obtained MB-SPAES membranes were transparent and mechanical ductile, suitable for PEM applications. Water uptake and size change results showed that the MB-SPAES membranes containing fluorenyl hydrophilic moieties absorbed less water and swelled smaller in water than the other two types at similar IECs, indicating their better dimensional stability. Proton conductivity and hydrolytic stability results indicated that the fluorenyl hydrophilic moieties were also favorable to gain better proton conductivity and hydrolytic stability.     

Sulfonated poly(ether ether ketone)/zirconium tricarboxybutylphosphonate composite proton-exchange membranes for direct methanol fuel cells

Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells. However, with a fairly high degree of sulfonation (DS), SPEEK membranes can swell excessively and even dissolve at high temperature. This restricts membranes from working above a high tolerable temperature to get high proton conductivity. To deal with this contradictory situation, insolvable zirconium tricarboxybutylphosphonate (Zr(PBTC)) powder was employed to make a composite with SPEEK polymer in an attempt to improve temperature tolerance of the membranes. SPEEK/Zr(PBTC) composite membranes were obtained by casting a homogeneous mixture of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on a glass plate and then evaporating the solvent at 60°C. Many characteristics were investigated, including thermal stability, liquid uptake, methanol permeability and proton conductivity. Results showed significant improvement not only in temperature tolerance, but also in methanol resistance of the SPEEK/Zr(PBTC) composite membranes. The membranes containing 30 wt-% ∼ 40 wt-% of Zr(PBTC) had their methanol permeability around 10^-7 cm²·s^-1 at room temperature to 80°C, which was one order of magnitude lower than that of Nafion ^¯115. High proton conductivity of the composite membranes, however, could also be achieved from higher temperature applied. At 100% relative humidity, above 90°C the conductivity of the composite membrane containing 40 wt-% of Zr(PBTC) exceeded that of the Nafion ^¯115 membrane and even reached a high value of 0.36 S·cm^-1 at 160°C. Improved applicable temperature and high conductivity of the composite membrane indicated its promising application in DMFC operations at high temperature.