质子交换膜用部分含氟磺化聚芳醚的合成与性能研究

通过直接磺化的方法,合成了一种部分含氟的磺化聚芳醚.由于特殊单体结构的设计,在聚合物主链上引入甲基取代基,对聚合物主链进行保护.用氯磺酸直接磺化方法在聚芳醚侧基上引入磺酸功能基,实现了聚合物磺化结构的可控定位合成,得到了稳定性较好的磺化聚芳醚.用溶液浇膜法制备了质子交换膜,研究了膜的各种性能.这种膜具有较高的导电性、吸水性和好的抗水解性、热稳定性.由于特殊结构的设计和部分氟的引入,这种膜的抗氧化性有显著的提高.     

磺化聚芳醚酮砜/PVA复合质子交换膜的制备与性能

为了进一步提高质子交换膜在中高温时的质子导电率,文中以高磺化度的磺化聚芳醚酮砜(SPAEKS)和聚乙烯醇(PVA)为原料,通过溶液共混法制备了PVA不同含量的磺化聚芳醚酮砜/PVA复合膜。通过对复合膜的性能测试发现,PVA的引入提高了膜的热稳定性、吸水率和保水能力。而且SPAEKS/PVA复合膜的质子传导率高于SPAEKS膜,在80℃时,复合膜的质子传导率都在0.07 S/cm以上,能够满足中高温质子交换膜燃料电池的使用要求。     

一种新型含氟含芴聚芳醚酮质子交换膜的合成和表征

以双酚芴、十氟联苯和磺化二氟酮为单体,合成磺化含氟聚芴醚酮(Sulfonated-fluo-rinated fluorene-containing poly(arylene ether ketone)s,SFPEEK).SFPEEK可溶于极性有机溶剂,具有较高的黏度,易于浇铸形成柔韧透明的薄膜.用其制成的质子交换膜表现出良好的热稳定性和抗水解、抗氧化性能.在相同测试条件下,SFPEEK膜具有与杜邦公司Nation 117膜相当的质子电导率,同时,具有比Nafion 117更好的耐甲醇渗透性能.直接甲醇燃料电池(DMFC)单池测试表明,放电到0.2 V时,用SFPEEK膜制备的单池电流密度可达66 mA/cm2,电池性能优于相同条件下用Nafion117膜组装的单池(电流密度60 mA/cm2).     

测试介质对纳米CeO_2改性SPEEK膜质子电导率的影响

采用纳米氧化铈(CeO2)改性磺化度48.3%的磺化聚醚醚酮(SPEEK),通过溶液浇铸法制备用于直接甲醇燃料电池的质子交换膜.在两种介质中测试改性膜的电导率均随温度的升高而增大,与未改性膜相比却大小正好相反:在1 mol/L以盐酸溶液为电解液的测试介质中,改性膜的电导率是未改性膜的15倍,在水蒸气测试介质中,却仅为40%.红外光谱分析表明,CeO2中的铈原子与—SO3H基团中的氧原子发生配位作用.X射线衍射仪(XRD)分析可见,当复合膜浸入1 mol/L盐酸4 h前后,纳米CeO2的晶体结构未见明显变化,表明所发生的配位作用仅处于CeO2和SPEEK两个固相界面上.扫描电子显微镜(SEM)观察改性膜和未改性膜均无网络结构和微相分离,质子在膜内通过—SO3H基团之间的跃迁传导,酸溶液介质远比水蒸气有利于质子在纳米CeO2改性SPEEK膜内磺酸基团之间的跃迁.     

Sulfonated carbon black-based composite membranes for fuel cell applications

Two different commercial grade carbon black samples, Cabot Regal 400R (C1) and Cabot Mogul L (C2), were sulfonated with diazonium salt of sulfanilic acid. The resultant sulfonated carbon black samples (S–C) were characterized by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Composite membranes were then prepared using S–C as fillers and sulfonated poly(ether ether ketone) (SPEEK) as polymer matrix with three different sulfonation degrees (DS = 60, 70 and 82%). Structure and properties of the composite membranes were characterized by FTIR, TGA, scanning electron microscopy, proton conduction, water uptake, ion exchange capacity and chemical stability. Incorporation of S–C particles above 0· 25 wt% caused decrease in chemical stability. Pristine and composite membranes prepared from SPEEK82 decomposed completely in $\boldsymbol{<}$ 1 h, which is undesirable for fuel cell applications. SPEEK60 membrane having wt% of 0·25–0· 5 with S–C particles led to higher proton conductivity than that of pristine membrane. No positive effect was observed on the properties of the composite membranes with the addition of S–C particles at high concentrations due to the agglomeration problems and decrease in the content of conductive polymer matrix.     

磺化聚芳醚酮砜/TiO2复合质子交换膜的制备与性能

为了满足高温燃料电池对质子交换膜的要求,通过溶胶共混法制备了掺有不同含量TiO2纳米粒子的磺化聚芳醚酮(SPAEKS)/TiO2复合膜。红外光谱证实TiO2被引入到SPAEKS共聚物中。扫描电镜(SEM)照片显示,纳米级的TiO2粒子能够均匀地分散在SPAEKS共聚物基体中。通过对复合膜的性能测试发现TiO2的引入,复合膜的热稳定性、吸水率、保水能力及阻醇性能都有所提高。而且SPAEKS/TiO2复合膜的质子传导率高于SPAEKS膜,并在高温时尤为明显,能够满足高温燃料电池的需要。     

主链刚性对磺化聚芳醚砜电解质膜性能的影响

以六氟双酚A(HFBPA)、9,9′-双(4-羟苯基)芴(BHPF)、4,4′-二氟二苯砜及3,3′-二磺酸钠-4,4′-二氟二苯砜为原料,经高温缩聚成功合成了一系列磺化聚芳醚砜(SPAES),并通过改变BHPF及HFBPA的比例来调节聚合物主链的刚性。结果表明,随刚性组分BHPF含量的增加,SPAES膜吸水率及质子导电率降低、但在水中的稳定性增加。在BHPF与HFBPA的比例为1∶1及磺化度为50%(SPAES50-50)条件下,膜在60℃水中平面和厚度方向的尺寸变化分别为0.12和0.13,电导率达到0.137 S/cm,而经130℃高温水处理200 h后的失重率仅为7%,表明其有望在高温燃料电池中得到应用。     

Synthesis and characterization of polystyrene-poly(arylene ether sulfone)-polystyrene triblock copolymer for proton exchange membrane applications

The polystyrene-poly(arylene ether sulfone)-polystyrene (PS-PAES-PS) coil-semirod-coil triblock copolymer was synthesized by the condensation reaction of PS-COCI and H2N-PAES-NH2 telechelic polymers. The reaction was facile characterized by high yields with a perfect control over the block lengths. Following a known reaction protocol it was possible to selectively sulfonate the PS block of the triblock copolymer that led to the sulfonated copolymer sPS-PAES-sPS. Studies on its proton conductivity and methanol permeability were carried out to evaluate its use as the proton exchange membrane in direct methanol fuel cells. Proton conductivity of the membranes was increased depending on the sulfonic acid group content in the sulfonated polymer. The membranes exhibited good dimensional and thermal stability, and low methanol permeability compared to Nafion 117.     

Near-infrared imaging of water in a polymer electrolyte membrane during a fuel cell operation

A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally.     

Preparation of nanosilver particles into sulfonated poly(ether ether ketone) (S-PEEK) nanostructures by electrospinning

By using the interaction between the sulfonated groups and silver ions, nanosilver particles were successfully introduced into S-PEEK nanostructures (nanospheres and nanofibers) by electrospinning. The nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectra (XPS), UV/vis, etc. The size of the spheres increases with the weight concentration of silver exchanged sulfonated poly(ether ether ketone) (S-PEEK-Ag) increasing. The size of the silver particles can be controlled by adjusting the sulfonated degree (number of sulfonate groups per repeating unit) of sulfonated poly(ether ether ketone) (S-PEEK) and the weight ratio of the S-PEEK solutions. This paper provides a new method for the preparation of nanometal particles into nanostructures.     

Fluorinated poly(ether sulfone) ionomers with disulfonated naphthyl pendants for proton exchange membrane applications

Proton exchange membranes based on fluorinated poly(ether sulfone)s with disulfonated naphthyl pendants (sSPFES) have been successfully prepared by post functionalization through polymeric S_NAr reaction. Copolymer structure was confirmed by H-nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy, the physico-chemical properties of the sSPFES membranes were evaluated by thermogravimetric analysis, gel permeation chromatography, electro-chemical impedance spectroscopy, atomic force microscopy, Fenton, water-swelling and fuel cell test. The pendant grafting degree was controlled by varying the feeding amount of the disulfonaphthols, resulting in the ion exchange capacity about 1.28-1.73 mmol/g. The obtained sSPFES membranes were thermal stable, mechanical ductile, and exhibited dimensional change less than 17%, water uptake below 70%, and proton conductivity as high as 0.17-0.28 S/cm at 90°C in water. In a single H₂/O₂ fuel cell test at 80°C, the sSPFES-B-3.2 membrane (1.61 mmol/g) showed the maximum power output of 593–658 mW/cm² at 60%-80% relative humidity, indicating their rather promising potential for fuel cell applications.     

Preparation of new proton exchange membranes using sulfonated poly(ether sulfone) modified by octylamine (SPESOS)

Sulfonated poly(arylene ether sulfone) (SPES) has received considerable attention in membrane preparation for proton exchange membrane fuel cell (PEMFC). But such membranes are brittle and difficult to handle in operation. We investigated new membranes using SPES grafted with various degrees of octylamine. Five new materials made from sulfonated polyethersulfone sulfonamide (SPESOS) were synthetized with different grades of grafting. They were made from SPES, with initially an ionic exchange capacity (IEC) of 2.4 meq g⁻¹ (1.3 H⁺ per monomer unit). Pristine SPES with that IEC is water swelling and becomes soluble at 80 °C, its proton conductivity is in the range of 0.1 S cm⁻¹ at room temperature in aqueous H₂SO₄ 1 M, similar to that of Nafion^®. After grafting with various amounts of octylamine, the material is water insoluble; membranes are less brittle and show sufficient ionic conductivity. Proton transport numbers were measured close to 1.     

Poly (ether ether ketone) derivatives: Synthetic route and characterization of nitrated and sulfonated polymers

Nitrated and sulfonated poly (ether ether ketone) [SNPEEK] samples were prepared through sulfonation of nitrated PEEK (NPEEK) at different temperatures resulting in polymers with distinct sulfonation degrees (SD). The sulfonation occurred preferentially in the hydroquinone segment even after 81% of this moiety had been nitrated. Sulfonation in the benzophenone moiety was achieved only in 16% of this segment at the reaction temperature of 80 °C. The substitution degree was obtained through the TG curves, and values were in agreement with ¹H NMR data when SD is much higher as ND (nitration degree). The highest SD obtained was 72%. Membranes of the sulfonated and nitrated PEEK (SNPEEK) were prepared by casting and showed good ductility depending on the substitution degree, with proton conductivity in the order of 10^? 2 S cm^? 1, an important characteristic in some applications, such as in fuel cells.     

Preparation and characterization of poly (methyl methacrylate) and sulfonated poly (ether ether ketone) blend ultrafiltration membranes for protein separation applications

Poly (methyl methacrylate) (PMMA) and poly (methyl methacrylate)/sulfonated poly (ether ether ketone) (SPEEK) blend membranes were prepared by phase inversion technique in various composition using N,N'-dimethylformamide as solvent. The prepared membranes were characterized in terms of pure water flux, water content, porosity and thermal stability. The addition of SPEEK to the casting solution resulted in membranes with high pure water flux, water content, porosity and slightly low thermal stability. The cross sectional views of the blend membranes under electron microscope confirm the porosity and water flux results. The effect of the addition of SPEEK into the PMMA matrix on the extent of bovine serum albumin (BSA) separation was studied. It was found that the permeate flux increased significantly while the rejection of BSA from aqueous solution reduced moderately during ultrafiltration (UF) process. The effect was attributed to the increase in porosity and charge of the membrane due to the addition of SPEEK into the PMMA blend solution.     

SPPESK/SPEEK共混质子交换膜的制备与性能

以耐溶胀性能较好的磺化聚芳醚砜酮(SPPESK)和吸水性较强的磺化聚醚醚酮(SPEEK)为原料,制备了SPPESK/SPEEK共混质子交换膜。考察了共混膜的水吸收率,水溶胀度,甲醇水溶胀度,甲醇渗透率及质子传导率和力学性能。80℃时,共混膜具有适当的水吸收(101%)和溶胀度(34%),较低的甲醇水溶胀度(20%),较高的质子传导率(0.212 S/cm),与SPPESK膜相比,质子传导率提高了18%。SPEEK的加入改善了共混膜的柔韧性,断裂拉伸应变从16.48%提高到30.43%。     

Self-regulation of the water drain in a hydrogen/oxygen fuel cell Communication II. Width of the self-regulation zone

Analyzed is the effect of various factors on the width of the self-regulation zone during a change in the rate of water drain and of water formation. The conditions are established under which a fuel cell with a capillary diaphragm should attain the maximum possible self-regulation after a change in current density.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 4, pp. 618–626, October, 1972.     

SiO2/sulfonated poly ether ether ketone (SPEEK) composite nanofiber mat supported proton exchange membranes for fuel cells

A composite membrane of silica (SiO₂)/sulfonated poly (ether ether ketone) (SPEEK) nanofiber mat impregnated with Nafion was fabricated and evaluated for its potential use as a proton conductor for high temperature polymer electrolyte membrane fuel cells. The supporting SiO₂/SPEEK composite nanofibrous skeleton was prepared via electrospinning of a mixture of SPEEK solution and silica sol prepared from tetraethyl orthosilicate (TEOS). The control of hydrolysis and condensation of TEOS enabled to form entangled SiO₂ networks miscible to SPEEK solution. The prepared SiO₂/SPEEK nanofiber mat was impregnated with Nafion^® to completely fill the inter-fiber voids to prepare a dense membrane. The morphology of the nanofiber mat and the composite membrane were observed by scanning electron microscopy and the presence of SiO₂ and SPEEK in the prepared nanofibers was confirmed by FTIR spectroscopy. Proton conductivity and swelling of the membrane were measured. The H₂/O₂ single cell test using the composite membrane as a PEM was performed. At a high temperature and low humidity condition (120 °C and 40 % RH), the maximum power density was 170 mW/cm² for the Nafion-impregnated SiO₂/SPEEK (40/60 w/w) composite nanofiber membrane that was 2.4 times higher than recast Nafion (71 mW/cm²) while SPEEK film failed.     

NEXAFS study of multi-walled carbon nanotubes functionalization with sulfonated poly(ether ether ketone) chains

Functionalization of multi-walled carbon nanotubes (MWNTs) surface by sulfonated poly (ether ether ketone) SPEEK chains using a direct attachment reaction was investigated. A two step method was performed. MWNTs were oxidized by a nitric acid treatment to generate carboxyl groups on their surface. The grafting reaction of sulfonated groups of SPEEK with carboxyl groups present on the surface of oxidized MWNTs readily proceeds by using hexane diamine as an interlinking molecule. Transmission electron microscopy (TEM) shows that tubes are wrapped by polymer chains. Near edge X-ray absorption fine structure spectroscopy (NEXAFS) at the C K-edge, O K-edge, and N K-edge and X-ray photoelectron spectroscopy (XPS) were used to give evidence of covalent functionalization of MWNTs by SPEEK macromolecules.     

Dihydrogenimidazole modified silica-sulfonated poly(ether ether ketone) hybrid materials as electrolyte membranes for direct ethanol fuel cells

The present study reports on dihydrogenimidazole modified inorganic-organic mixed matrix membranes for possible application as a proton exchange membrane in direct ethanol fuel cells. The polymeric phase consisted mainly of sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree of 55%. The inorganic phase was built up from hydrophilic fumed silica particles interconnected with partially hydrolyzed and condensed tetraethoxysilane with a total inorganic loading of 27.3%. This inorganic phase was further modified with N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (DHIM), which consists of an hydrolyzable inorganic part and a functional organic group. The influence of the modifier on the mixed matrix system was studied by means of various modifier concentrations in various aqueous-ethanolic systems (water, 2 M and 4 M ethanol). Modifier concentration and ethanol concentration of the ethanol-water mixture exhibited significant but opposite effects on the liquid uptake of the mixed matrix membranes. The proton conductivity as well as the proton diffusion coefficient as a function of modifier content showed a linear decrease. The proton conductivity as a function of temperature showed Arrhenius behavior and the activation energy of the mixed matrix membranes was 43.9 ± 2.6 kJ mol⁻¹. High selectivity of proton diffusion coefficient to ethanol permeability coefficient was obtained with high modifier concentrations. At low modifier concentrations, this selectivity was dominated by ethanol permeation and at high modifier concentrations by proton diffusion. The main electrolyte properties can be optimized by setting the DHIM content in mixed matrix membrane. With this approach, tailor-made membranes can be prepared for possible application in direct ethanol fuel cells.     

一种新型的磺化聚芳醚酮质子交换膜材料

利用先聚合后磺化的方法合成了一种新型磺化聚芳醚酮,FTIR和HNMR结构表征表明,其磺酸基只连在悬挂侧链上.利用浇铸法将该材料制备成膜,对膜的离子交换容量(IEC)、平均当量重量(EW)、磺化度(SD)、吸水性、线性膨胀率及其电导率进行了表征,结果表明这种膜材料具有良好的吸水性和较低的线性溶胀率,所制得的膜在100℃、100%相对湿度时的质子电导率与Nafion-117~(R)膜相近,有望作为质子交换膜使用.