SPES Membrane Research Articles

Mussel-inspired modification of ion exchange membrane for monovalent separation

Electrodialysis (ED) is a promising and widely used technique for producing drinking water. Nevertheless, the presence of multivalent ions like Mg2+ and Ca2+ can be challenging in practical applications, because this leads to precipitation in the concentrated compartment, thus decreasing the performance of the ED process. Monovalent ion exchange membranes are capable of separating monovalent ions from a solution containing both mono- and multivalent ions, which can be applied for water softening. The monovalent ion selectivity of an ion exchange membrane in electrodialysis is greatly dominated by its surface structure and properties. In this study, a simple method is proposed by co-depositing mussel-inspired polydopamine (PDA) with polyethyleneimine (PEI) to modify a self-prepared sulfonated poly (ether sulfone) (SPES) ion exchange membrane. The effects of the PEI content on the monovalent selectivity were studied. When the optimized parameters were used in ED, the permselectivity of SPES-PDA/PEI-2 was 2.5 times higher than that of the SPES membrane. Especially the flux of H+ was enhanced. Furthermore, the PDA/PEI modified ion exchange membrane shows excellent operation stability for monovalent separation performance after immersion in acid and alkaline solution for 7 days. Comparing membranes prepared with different molecular weights of PEI, results revealed that modification with a lower molecular weight PEI yields a higher selectivity. This facile strategy may provide new opportunities not only to develop monovalent ion exchange membranes but also to engineer the surface of numerous materials in energy and environmental applications.

Preparation and characterization of SPES/PVA (double-layer) membrane for vanadium redox flow battery

The double-layer membrane consisting of sulfonated poly(ether sulfone) (SPES) sub-layer and polyvinyl alcohol (PVA) sub-layer (denoted as SPES/PVA membrane) was prepared and employed as the separator for vanadium redox flow battery (VRB) system to evaluate the vanadium ions permeability and cell performance. The SPES/PVA membrane is a double-layer structure and exhibits dramatically lower vanadium ions permeability and better cell performance compared to the pristine SPES membrane, PVA membrane, and Nafion117 membrane. The vanadium ion permeability of SPES/PVA membrane is one order of magnitude lower than that of Nafion117 membrane. In further work, the single cell with SPES/PVA membrane showed significantly lower capacity loss, higher coulombic efficiency (>92.5%), and higher energy efficiency (>83.9%) than Nafion117 membrane. In the self-discharge test, SPES/PVA membrane showed 1.8 times longer duration in the open circuit decay than Nafion117 membrane. With all the good properties and low cost, this new kind of double-layer membrane is suggested to have excellent commercial prospects as an ion exchange membrane for VRB systems.

High Performance Nanocomposite Cation Exchange Membrane: Effects of Functionalized Silica-Coated Magnetic Nanoparticles

Nanocomposite cation exchange membranes (CEMs) were prepared by adding various amounts of functionalized silica-coated magnetite nanoparticles to the sulfonated polyethersulfone (sPES) polymeric matrix. The particles were synthesized first by the co-precipitation method (M0). Different surface modifications were then carried out on them by grafting three functional groups of mercaptopropyl, propylsulfonic acid, and sulfonic acid to yield functionalized particles of M1, (M2, ion exchange capacity (IEC)= 3.09 meq.g-1), and (M3, IEC= 2.88 meq.g-1), respectively. The SEM images of nanocomposite membranes verified a uniform dispersion of the nanoparticles in the membrane matrix. The nanoparticles provided more ion exchange groups and regulated water content of the membrane, and consequently enhanced its transport properties, IEC, and conductivity. The maximum values of IEC and conductivity of nanocomposite membranes were 1.8 meq.g-1 and 0.274 S.cm-1 corresponded to the membranes having 3 and 2 wt% of M2 nanoparticles, respectively. The maximum ion conductivity of nanocomposite membrane was about 2 times higher than that of sPES membrane. The nanocomposite membranes containing functionalized silica-coated magnetic nanoparticles showed superior IEC, water uptake, membrane conductivity, and transport number compared to those values for the membranes containing corresponded functionalized silica nanoparticles.

Effects of functionalized silica nanoparticles on characteristics of nanocomposites PES cation exchange membranes

Nanocomposite cation exchange membranes (CEMs) were prepared by adding various loadings of functionalized silica nanoparticles to the sulfonated polyethersulfone (sPES) polymeric matrix. The silica nanoparticles were functionalized by mercaptopropyl (F1, IEC=0), propylsulfonic acid (F2, IEC= 2.71), and sulfonic acid (F3, IEC=2.84). The properties of prepared membranes were investigated by varying the loadings of functionalized silica nanoparticles. Applying functionalized nanoparticles provides additional ion exchange groups and enhances water contents as well as conductivities and permselectivities of the membranes. The maximum IEC of 1.9 meq.g-1 was obtained for the membrane having 3wt% F3 nanoparticles and the maximum conductivity of 0.237 S·cm-1 was achieved for the membrane having 2wt% F3 nanoparticles, which were 19.6% and 64% higher than the corresponding values for sPES membrane, respectively. The excellent properties of the nanocomposite cation-exchange membranes make them appropriate candidates for electrodialysis and desalination processes.

Fabrication and electrochemical properties of highly selective SPES/GO composite membranes for direct methanol fuel cells

Graphene oxide (GO) was synthesized and used as an additive at various proportions with the intention of fabrication of sulfonated poly (ether sulfone) (SPES) based composite proton exchange membranes (PEMs) for direct methanol fuel cell (DMFC) applications. Among the various composite membranes prepared, SPES/GO (1wt%) was found to have the highest selectivity with a water uptake of 40.1%, proton conductivity of 4.3×10−3S/cm, and methanol permeability of 4.923×10−8cm2/s. The introduction of GO in membranes not only improved proton conductivity, but also positively affected the mechanical properties and the blocking of methanol molecules passing through the membrane. Consequently, the incorporation of GO into SPES membrane has considerably increased the selectivity of the membrane. Therefore, SPES/GO membranes showed three folds increase in performance than original SPES membrane, and hence acted as a good candidate for use in DMFC in order to resolve current issues of methanol crossover.

Separation of mixed amino acids by BMED process using porous SPES and SPSf cation exchange membranes

Abstract Porous sulfonated polyethersulfone and polysulfone (SPES and SPSf) cation exchange membranes were prepared by phase inversion process, in which water was used as the coagulation bath at 4 °C or 25 °C. Dense SPES and SPSf cation exchange membranes were also prepared for comparison. Characterizations of the membrane structure, morphology and physico-chemical properties showed that the dense membranes are hydrophobic with large area resistance (>80 Ω cm 2 ), while the porous membranes are hydrophilic with low area resistance (0.35–18.62 Ω cm 2 ). The porous SPSf membranes have lower area resistance (0.35–0.81 Ω cm 2 ) than SPES membranes due to their higher water uptake (289.1–370.1%) and special morphology containing oval-shaped pores in the top skin layer. The membranes are utilized in bipolar membrane electrodialysis (BMED) process to separate the mixed amino acids of l -glutamic acid (Glu) and l -lysine (Lys). Though the dense membranes are unsuitable for electrodialysis experiments due to the large area resistance, the porous membranes have higher recovery ratio and current efficiency than the commercial membrane CMX, for the Lys + can migrate through the porous membranes with lower hindrance. In addition, the SPSf membranes have higher Glu leakage ratio (13.9–15.3%) and lower energy consumption (4.82–6.52 kWh/kg) than the SPES membranes (∼0%, 6.43–9.53 kWh/kg). What’s more, the water permeation can be controlled by membrane materials and pore structures.

Preparation and characterization of proton exchange membranes with through-membrane proton conducting channels

The primary goal of this study is to develop a novel PEMs with unique surface structure utilizing the high viscosity of the impregnation solution. SiO2 nanofiber mats were prepared via the electrospinning method and introduced into sulfonated poly(ether sulfone) (SPES) matrix to prepare hybrid membrane. The effect of concentration of impregnation solution on the morphology and properties of the proton exchange membranes (PEMs), including thermal stability, water uptake, dimensional stability, proton conductivity, and methanol permeability were investigated. SEM results showed that a unique surface structure was prepared due to the high solution concentration. Moreover, the hydrophilic nanofibers on the surface constructed continuous proton pathways, which can enhance the proton conductivity of the membranes, a maximum proton conductivity of 0.125 S/cm was obtained when the SPES concentration was 40 wt% at 80 °C, and the conductivity was improved about 1.95 times compared to that of pure SPES membrane. The SiO2 nanofiber mat-supported hybrid membrane could be used as PEMs for fuel cell applications.

Hydrated proton self-diffusion study in ion-exchange membranes by MRI and impedance spectroscopy

Average self-diffusion coefficients of hydrated protons in sulfonated poly (ether sulfone) (SPES), Interpolymer and Nafion 117 membranes are measured by impedance spectroscopy and pulsed field gradient nuclear magnetic resonance (PFG NMR). Self-diffusion coefficient measured by impedance spectroscopy shows two patterns, one is at the low hydration states, i.e. λ = 2–4 and another at the high hydration states (starting from λ = 4). At lower hydration states the diffusion values increases slowly while steep increment is found at higher hydration level. PFG NMR shows similar trend throughout the measurements. The diffusion coefficients at higher temperatures are higher than at lower temperatures as a function of λ for SPES membrane. At the same value of λ, hydrated proton self-diffusion coefficient is found to be increased by 18% from 295.5 to 303 K. The thermo-mechanical properties of the membranes characterised by the means of DSC, TGA and DMA analysis show SPES, stable up to 450 °C and can be used for the high-temperature applications.

Hybrid nanocomposite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica for direct methanol fuel cells

Composite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica (SPES/CDI/AS/SiO2) with silica of various contents (3, 5 and 8 wt%) were prepared as electrolytes for direct methanol fuel cells (DMFCs). Comparison was made with pure SPES and SPES/SiO2. The properties of the composite membranes were studied by FTIR, TGA, XRD, water and methanol uptake, proton conductivity. SPES/CDI/AS/SiO2 membranes were also characterized by scanning electron microscopy (SEM), which showed good adhesion between the modified sulfonic acid (-SO3H) groups of SPES and silica because of cross-linking with covalent bond formation and reduced cavities in the composites. This effect played an important role in reducing water uptake, methanol uptake and methanol permeability of the SPES/CDI/AS/SiO2 composites. The water and methanol uptake and also methanol permeability of the SPES/CDI/AS/SiO2 composite membrane with 8% SiO2 were found in the order 3.58%, 2.48% and 1.91×10−7 (cm2s−1), lower than those of SPES and Nafion 117. In SPES membrane of 16.94% level of sulfonation, the proton conductivity was 0.0135 s/cm at 25 °C, which approached that of Nafion 117 under the same conditions. Also, the proton conductivity of the SPES/CDI/AS/SiO2 8% membrane was 0.0186 s/cm, which was higher than that of SPES at room temperature. The preparation of SPES/SiO2 composites in the presence of AS and CDI, led to 63%, 56% and 64% reduction of water uptake, methanol uptake and methanol permeability, respectively without a sharp drop in proton conductivity of the composite membranes which featured a good balance between high proton conductivity, water and methanol uptake of SPES/CDI/AS/SiO2 membranes.

Development of Sulfonated Poly(Arylene Ether Sulfone) Multi-Block Membranes for Low RH PEMFC Operation

Perfluorosulfonic acid (PFSA) polymers are the most promising state-of-the-art materials as proton exchange membranes (PEM) for fuel cells, however, there are some drawbacks such as high production cost and hydrothermal stability. Aromatic membranes based on hydrocarbon polymers have been studied as alternatives. Among them, multi-block copolymers seem to be promising to compete with PFSA resulting high proton conductivity even under low RH conditions.[1, 2] In this report, novel sulfonated poly(arylene ether sulfone)s multi-block copolymer membranes containing highly sulfonated hydrophilic blocks were synthesized.[3] Different local concentration of sulfonic acid in their hydrophilic blocks affected chemical and physical properties of the SPAES. To investigate the effects of chemical composition on their membrane properties, different hydrophilic oligomers sharing same hydrophobic blocks gave us exact comparison of effect of hydrophilic blocks. The higher concentration of sulfonic acid groups resulted in higher proton conductivity under certain relative humidity conditions than that of the state-of-the-art perfluorinated sulfonic acid membrane and showed that the well-developed phase separation of SPAES. Moreover, physical properties of theses SPAES including water behavior, humidity dependence of proton conductivity were investigated along with morphology characterizations by transmission electron microscopy (TEM) for PEMFC application. Two types of oligomers, F-terminated and OH-terminated telechelic oligomers, were synthesized by controlling the feed ratio of dihydroxyl- and difluoro-monomers. Their number of repeating unit (X and Y) was analyzed by GPC and 1H NMR. Copolymerization with F-terminated and OH-terminated telechelic oligomers via nucleophilic aromatic substitution, gave high-molecular-weight multi-block PESs. Each block length was controlled to have different values with X5Y10, X10Y10, X20Y10 and X20Y20. The SPAES X10Y10 membrane showed highest proton conductivity than that of our previous random and block copolymers at wide range of humidity. The best balanced membrane was SPAES X10Y5 membrane with high proton conductivity and lower water uptake. Consequently, the SPAES X10Y5 membrane showed high cell performance under various conditions (510 mA/cm2, 290 mA/cm2 @ 0.6V under 80% and 50 % RH conditions at 80℃, respectively). Systematic approaches for developing alternative block SPES membrane for low RH condition will be discussed.

Quaternized graphene oxide modified ionic cross-linked sulfonated polymer electrolyte composite proton exchange membranes with enhanced properties

A series of novel ionic cross-linked sulfonated poly(ether sulfone) (SPES)-based proton exchange membranes (PEMs) were successfully constructed by using quaternized graphene oxide (QGO) as the inorganic fillers and cross-linking agents. The ionic cross-linking networks were implemented by the interactions between the sulfonic acid groups of SPES and the quaternary ammonium groups of QGO. The influences of different loading contents of QGO on the properties of the ionic cross-linked composite membranes were studied. The composite membranes showed the enhanced mechanical properties and improved oxidative stabilities. Meanwhile, the swelling ratio, water uptake and methanol permeability of the ionic cross-linked SPES/QGO composite membranes were much lower than that of the pristine SPES membrane. The swelling ratio and water uptake of SPES-10-QGO composite membrane had the minimum values among all the composite membranes. In addition, although the proton conductivity of ionic cross-linked SPES membranes by QGO decreased, SPES-10-QGO still exhibited high proton conductivity of about 0.08Scm−1 at 80°C. All the results indicated that the ionic cross-linked composite membranes with balanced properties were the potential candidate materials for PEMs.

Sulfonated poly(ether sulfone)/poly(vinylidene fluoride) hybrid membrane for vanadium redox flow battery

Sulfonated poly(ether sulfone)/poly(vinylidene fluoride) (SPES/PVDF) blends are prepared and employed as the separator for vanadium redox flow battery (VRB) to evaluate the vanadium ions permeability and cell performance. The SPES/PVDF membranes exhibit dramatically vanadium ions permeability and cell performance compared with pristine SPES and Nafion115 membrane. The vanadium ion permeability of SPES/PVDF membrane is 1 order of magnitude lower than that of Nafion115 membrane. The low-cost composite membrane exhibits a better performance than Nafion115 membrane at the same operating condition. VRB single cell with SPES/PVDF membrane shows significantly lower capacity loss, higher coulombic efficiency (>98%) and higher energy efficiency (>84%) than that with Nafion115 membrane. In the self-discharge test, S0.7P0.3 membrane shows twice longer duration in the open circuit decay than that with Nafion115 membrane. With all the good properties and low cost, the SPES/PVDF membrane is expected to have excellent commercial prospects as an ion exchange membrane for VRB systems.

Mesoporous ceria-silica/poly(arylene ether sulfone) composite membranes for durability of fuel cell electrolyte membrane

Sulfonated poly(arylene ether sulfone) (sPES)/mesoporous ceria-silica electrolyte composite membranes were prepared using a solvent casting method. The composite membranes with two components were prepared well on glass dish using dimethyl sulfoxide (DMSO) as well as N,N-dimethyl acetamide (DMAc) solvents, at various concentrations from 2.5 up to 30 wt% of the mesoporous ceria-silica powder. The degree of sulfonation was 50% for sPES and the mesoporous ceria-silica material had a 2D hexagonal (p6mm) mesostructure with the Ce/Si ratio of 0.5 and the sulfur atoms of 3.1 mmol/g in sulfonic acid groups. The oxidation stability against hydroxyl radicals (OH) was investigated both with Fenton's test and the hydrogen peroxide exposure. Hydrogen peroxide vapor exposure experiments was developed to screen the oxidation stability in a short time under high temperature and low relative humidity conditions, which is more similar to actual fuel cell system. The composite membranes exhibited higher oxidation stability than a pristine sPES membrane. However, the proton conductivity decreased with the incorporation of mesoprous ceria-silica, which should be resolved through further study using combination of the polymer matrix with different structure and the modification of mesoporous ceria-silica.

Hydrocarbon-based polymer electrolyte cerium composite membranes for improved proton exchange membrane fuel cell durability

Hydrocarbon-based cerium composite membranes were prepared for proton exchange membrane fuel cell applications to increase oxidative stability. Different amounts of cerium ions were impregnated in sulfonated poly(arylene ether sulfone) (SPES) membranes and their physicochemical properties were investigated according to the cerium content. Field-emission scanning electron microscopy and inductively coupled plasma analyses confirmed the presence of cerium ions in the composite membranes and 1H NMR indicated the successful coordination of sulfonic acid groups with the metal ions. Increasing amounts of cerium ions resulted in decreases in the proton conductivity and water uptake, but enhanced oxidative stability. The oxidative stability of the composite membranes was proven via a hydrogen peroxide exposure experiment which mimicked fuel cell operating conditions. In addition, more than 2200 h was achieved with the composite membrane under in situ accelerated open circuit voltage (OCV) durability testing (DOE protocol), whereas the corresponding pristine SPES membrane attained only 670 h.

Preparation and Characterization of Sulfonated Poly (Ether Sulfone) (SPES)/Phosphotungstic Acid (PWA) Hybrid Membranes for Biodiesel Production

A new kind of organic–inorganic hybrid membrane based on sulfonated poly (ether sulfone) (SPES) with different degree of sulfonation (DS) embedded phosphotungstic acid (PWA) was prepared as a heterogeneous acid catalyst for biodiesel production. Three kinds of hybrid membranes with the DS of SPES 9.7, 20.3 and 39.1 % were obtained. The interactions between SPES and PWA in SPES/PWA hybrid membrane were characterized by Fourier transform infrared (FTIR), thermogravimetric analysis and X-ray diffraction (XRD). The band shift of FTIR spectrum showed that the PWA particles interacted primarily with sulfonic acid groups on the polymer backbone. Compared to pure SPES membrane, the thermal stability of SPES/PWA hybrid membrane was enhanced. The XRD results suggested that the PWA particles were incorporated inside membrane pores and adhered on the walls outside the pores which were due to the interaction between PWA and SPES polymer matrix. The catalytic properties of SPES/PWA membranes were tested by the esterification of the acidified oil with methanol. The reaction conditions were optimized by response surface model and the optimum conditions were obtained as: methanol/oil mass ratio of 1:1, hybrid membrane loading of 1.66 meq/g and reaction time 6 h with the free fatty acids conversion of 95.3 %. The hybrid membrane with SPES/PWA mass ratio of 2:1 and the membrane thicknesses of 0.06 mm were optimal for the esterification. The SPES/PWA membrane of DS 20.3 % exhibited the best catalytic stabilities among the three kinds of hybrid membranes with different DS with a stable conversion of above 90 % in all times.

Synthesis of poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane and its application as a proton-conducting membrane

A polysilsesquioxane-based organic-inorganic hybrid membrane was prepared and applied as a proton-conducting membrane for fuel cells. poly(STES-ran-MTES), a random copolymer of ethyl 4-(2-methyl-3-triethoxysilylpropoxy)benzenesulfonate (STES) and triethoxy(methyl)silane (MTES) was synthesized by hydrolysis and condensation in the presence of hydrochloric acid under a nitrogen stream. The molecular weight was 7500–7600 g mol−1, and the percentage of hydrolyzed ethoxysulfonyl group was 32–50%. A poly(STES-ran-MTES) membrane was prepared by heating for several days, which showed thermal resistivity up to 200 °C and proton conductivity of 2.0 × 10−5 to 1.1 × 10−3 S cm−1 at room temperature. By contrast, a membrane of a block copolymer, poly(SPES-block-PMS), showed proton conductivity of 2.5 × 10−3 S cm−1. The proton conductivity of the poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane (SPES) membrane increased from 2.7 × 10−3 S cm−1 at 25 °C to 1.0x10−2 S cm−1 at 110 °C. The proton conductivity of the SPES membrane increased from 2.7 × 10−3 S cm−1 at relative humidity (RH)=25–30% to 2.0 × 10−3 S cm−1 at RH=60% and 1.4 × 10−1 S cm−1 at RH=90%. The mixture of SPES and poly(vinyl alcohol), poly(ethylene oxide) or polyoctahedralpolysilsesquioxane showed proton conductivities of 2.7 × 10−3, 1.5 × 10−3 and 2.5 × 10−3 S cm−1, respectively, at 25 °C and RH=25–30%. The open-circuit voltage of the SPES membrane was 0.92 V. A polysilsesquioxane-based organic-inorganic hybrid membrane was prepared and applied as a proton-conducting membrane for fuel cells. A membrane of a random copolymer of ethyl 4-(2-methyl-3-triethoxysilylpropoxy)benzenesulfonate and triethoxy(methyl)silane showed proton conductivity of 2.0 × 10−5 to 1.1 × 10−3 S cm−1 at room temperature. A membrane of a block copolymer of poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane (SPES) and polymethylsilsesquioxane showed proton conductivity of 2.5 × 10−3 S cm−1. The mixture of SPES and poly(vinyl alcohol), poly(ethylene oxide), or polyoctahedralpolysilsesquioxane showed proton conductivity of 2.7 × 10−3, 1.5x10−3 or 2.5 × 10−3 S cm−1, respectively. The open-circuit voltage of the SPES membrane was 0.92 V.

Highly stable acid–base complex membrane for ethanol dehydration by pervaporation separation

An investigation has been performed into the pervaporation (PV) of the water–ethanol azeotrope using sulphonated poly(ethersulphone) (SPES)–polyethyleneimine (PEI) membranes, the performance of which is compared to the SPES membrane. The SPES–PEI membranes showed high selectivity because of their alternating electrostatic deposition which yields ultrathin, water-selective polyelectrolyte membranes. The thermal and mechanical stabilities of the prepared membranes have been investigated using DSC, TGA, DMA and their structural properties by SEM. The addition of the functional group has been confirmed by solid state 13C NMR and FTIR spectroscopy. The thermal and mechanical data showed that the membranes are mechanically stable up to 250 °C. The glass transition temperature and peak sharpness increases with the quantity of the PEI component, which indicates a rise in the molecular hybridization. FTIR spectra confirm the addition of various functional groups in SPES due to the addition of PEI. The membranes containing 20% (w/w) PEI exhibited the highest water–ethanol selectivity, of the order of 4185 and a flux of 1.2 kg m−2 h−1 at 30 °C.

고분자연료전지용 설폰산화 폴리아릴렌에테르설폰 멀티블록공중합체의 합성 및 특성 분석

Abstract >> Multi-block sulfonated poly (arylene ether sulfone) (SPES) membranes were synthesized by post-sulfonationand its properties characterized. Two types of oligomers, F-terminated and OH-terminated telechelic oligomers, were synthesized by controlling the feed ratio of dihydroxyl- and difluoro-monomers. Their number of repeating unit (X and Y) was analyzed by GPC and 1 H NMR. Copolymerization with F-terminated and OH-terminated telechelic oligomers via nucleophilic aromatic substitution, gave high-molecular-weight multi-block PESs. Each blocklength was controlled to have different values with X5Y10, X10Y10, X20Y10 and X20Y20. Successful polymerizationand its successful sulfonation was confirmed by GPC and 1 H NMR. RH dependence of proton conductivity of multi-block SPES membranes was comparable to that of Nafion 212 at high RH conditions. Key words : PEMFC(고분자전해질연료전지), Electrolyte membrane(전해질막), Poly(arylene ether sulfone, 폴리아릴렌에테르설폰), Proton conductivity(양성자전도도), Sulfonation(설폰산화)

Synthesis and preparation of sulfonated hyperbranched poly(arylene ether sulfone)/poly(ether sulfone) blend membranes for proton exchange membranes

A series of sulfonated hyperbranched poly(arylene ether sulfone)s (SHPAESs) have been synthesized by aromatic nucleophilic substitution reaction of 1,1,1-tris(4-hydroxyphenyl)ethane (THPE), 4,4′-dichlorodiphenyl sulfone (DCDPS) and 3,3′-disulfonate-4,4′-dichlorodiphenyl sulfone (SDCDPS), and then the blend membranes of SHPAESs with sulfonated linear poly(ether sulfone) (SPES) (SHPAESs/SPES) have been prepared for proton exchange membrane. All the blends can be cast into tough membranes, and they are miscible in morphology confirmed by scanning electron microscopy. The thermal stability, mechanical property, oxidative stability, ionic exchange capacity (IEC), water uptake and proton conductivity of the blend membranes have been investigated. The results showed that the blend membranes have good thermal and mechanical properties, better stability in water comparing with the linear SPES membrane, and the other promising properties as a new proton exchange membrane for fuel cell application.

Sulfonated multiwalled carbon nanotube/sulfonated poly(ether sulfone) composite membrane with low methanol permeability for direct methanol fuel cells

AbstractAn organic/inorganic composite membrane was prepared based on sulfonated poly(ether sulfone) (s‐PES) embedded with sulfonated multiwalled carbon nanotubes (s‐MWNTs). The ion exchange capacity (IEC), proton conductivity, and water uptake of the SPES membranes increased with increasing s‐MWNTs content. The increased water uptake was attributed to hydrogen bond formation between the carbonyl group of the s‐MWNTs and a water molecule. The composite membranes exhibited proton conductivities ranging from 3.9281 × 10−4 to 7.0788 × 10−3 S/cm at 80°C, as well as low methanol permeability ranging from 4.4405 × 10−10 to 9.1008 × 10−10 cm2 s−1 at 25°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012