Poly(arylene ether)s carrying pendant (3‐sulfonated) phenylsulfonyl groups

A series of poly(arylene ether)s with biphenyl units and pendant sulfonated phenylsulfonyl groups was prepared via nucleophilic aromatic substitution reactions of varying ratios of 3,5‐difluoro‐3′‐sulfonated diphenylsulfone and 4,4′‐difluorodiphenylsulfone with 4,4′‐biphenol. As such, the sulfonic acid moieties reside in the meta position of a pendant, electron‐poor phenylsulfonyl group. Mechanically robust proton‐exchange membranes with ion‐exchange capacities (IEC) ranging from 0.91 to 2.05 meq g^?1 were cast from dimethylacetamide. The thermal stability of the membranes was evaluated via thermogravimetric analysis and the 5% weight losses were found to be in excess of 330 °C in air. The glass transition temperatures were determined, via differential scanning calorimetry, to range from a low of 148 to a high of 209 °C at IEC values of 0.91 and 1.79 meq g^?1, respectively. The copolymer membranes reached proton conductivities as high as 142 mS cm^?1 under 100% relative humidity, with relatively low water uptake values (8–32 wt%). Copyright © 2012 Society of Chemical Industry     

Synthesis and characterization of poly(arylene ether ketone) (co)polymers containing sulfonate groups

Poly(arylene ether ketone)s containing sulfonate groups were synthesized by aromatic nucleophilic polycondensation of 4,4′-difluorobenzophenone (DFK), sodium 2,5-dihydroxybenzensulfonate (SHQ) and bisphenols. Only low-molecular weight oligomer was obtained when hydroquinone (HQ) was employed as comonomer, while copolymerization of DFK, SHQ, and phenolphthalein (PL) proceeded quantitatively to high-molecular weight (reduced viscosities above 0.68 dL/g) in dimethylsulfoxide at 175 °C in presence of anhydrous potassium carbonate. The sulfonated polymers were soluble in dipolar aprotic solvents, such as N,N-dimethylactamide and N-methyl-2-pyrrolidinone. Tough membranes cast from N,N-dimethylformamide solution with SHQ/DFK mole ratios ≤65:35 were obtained. Both glass transition temperatures and hydrophilicity of the copolymers increased with the content of sodium sulfonate groups. The materials are candidates as new polymeric electrolytes for proton exchange membranes.     

Sulfonation and characterization of poly(styrene-isobutylene-styrene) triblock copolymers at high ion-exchange capacities

In this study, a triblock copolymer, poly(styrene-isobutylene-styrene), was sulfonated to eight different levels ranging from 0.36 to 2.04 mequiv./g (13 to 82 mol% of styrene; styrene is 19 mol% of the unsulfonated block copolymer). These sulfonated polymers were characterized with elemental analysis and infrared spectroscopy to confirm sulfonation and determine accurate sulfonation levels. Infrared analysis revealed four additional stretching vibrations as a result of sulfonation. Also, a linear relationship between absorbance at 1006 cm⁻¹ (stretching of the aromatic ring in styrene caused by the para-substituted sulfonic acid) and sulfonation level (measured by elemental analysis) was found. The density and water solubility of all the sulfonated polymers were measured and increased with increasing sulfonation level, as high as 1.31 g/cm³ and 351 wt%, respectively. In addition, a sulfonated triblock copolymer at 79 mol% sulfonation was neutralized with a cesium cation and revealed an increase in density, but a reduction in water solubility. This study demonstrates the resulting unique properties of sulfonated styrene-based block copolymers at higher ion-exchange capacities than previously reported.     

Sulfonated aromatic hydrocarbon polymers as proton exchange membranes for fuel cells

This article reviews recent studies on proton exchange membrane (PEM) materials for polymer electrolyte fuel cells. In particular, it focuses on the development of novel sulfonated aromatic hydrocarbon polymers for PEMs as alternatives to conventional perfluorinated polymers. It is necessary to improve proton conductivity especially under low-humidity conditions at high operating temperatures to breakthrough the current aromatic PEM system. Capable strategies involve the formation of well-connected proton channels by microphase separation between hydrophilic and hydrophobic domains and the increase of the ion exchange capacity of PEMs while keeping water resistance. Herein, we introduce novel molecular designs of sulfonated aromatic hydrocarbon polymers and their performance as PEMs.     

New multiblock copolymers of sulfonated poly(4′-phenyl-2,5-benzophenone) and poly(arylene ether sulfone) for proton exchange membranes. II

Rigid-rod poly(4′-phenyl-2,5-benzophenone) telechelics were synthesized by Ni(0) catalytic coupling of 2,5-dichloro-4′-phenylbenzophenone and the end-capping agent 4-chloro-4′-fluorobenzophenone. The degree of polymerization was determined by ¹³C NMR. The telechelics produced were selectively sulfonated by concentrated sulfuric acid at 50 °C. The degree of sulfonation was controlled by varying the reaction time and was determined by titration. The nucleophilic step copolymerization of the fluoroketone activated sulfonated poly(4′-phenyl-2,5-benzophenone) oligomer (M_n=3.05×10³ g/mol) with hydroxyl terminated biphenol based polyarylethersulfone (M_n=4.98×10³ g/mol) afforded an alternating multiblock sulfonated copolymer that formed flexible transparent films, in contrast to the high molecular weight rigid rod homopolymers. They were tested for water absorption and proton conductivity by specific impedance. The synthesis and characterization of these multiblock copolymers are reported.     

车用燃料电池质子交换膜的制备及性能

合成了一系列具有不同支化度的磺化聚芳醚砜材料,并对其结构和性能进行了表征。所制备的磺化的支化聚芳醚砜材料的分子量可达7.00×105以上,并且分子量分布在1.17左右,拉伸强度可达20.55~28.81 MPa。随着聚合物支化度的增加,聚合物的热稳定性得到改善,在550℃下的热失重可降低至39%~45%。高支化的磺化聚芳醚砜薄膜的氧化稳定性也得到改善,80℃下的使用寿命可提高至7.25 h。支化的磺化聚芳醚砜薄膜的吸水率和质子传导率都较高。80℃下高支化度的聚芳醚砜薄膜的质子传导率可达0.33 S/cm。对其微观形貌进行观测发现,支化聚芳醚砜中的支化结构可对周围的亲水磺酸基团起支撑作用,促使其发生团聚而形成连续的质子通道。     

磺化芳香聚合物复合质子交换膜

磺化芳香聚合物与其他聚合物共混制备复合膜是改善磺化芳香聚合物质子交换膜性能的一种有效方法。就最近几年来碱性聚合物及其他聚合物与磺化芳香聚合物复合的研究现状进行了分析，对其中存在的问题进行了阐述。     

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.     

Synthesis and properties of sulfonated poly(2,5-diphenethoxy-p-phenylene)

A novel regio-controlled poly(2,5-diphenethoxy-p-phenylene) partially functionalized with sulfonic acids has been developed for a proton exchange membrane. Poly(2,5-diphenethoxy-p-phenylene) was prepared via the oxidative-coupling polycondensation using iron(III) trichloride as an oxidant. A high molecular weight polymer over 270,000 in the weight-average molecular weight was quantitatively obtained in mild conditions. This polymer was then reacted with two and four equimolar trimethylsilylchlorosulfonate in dichloromethane to give the corresponding sulfonic acid-functionalized polymers, whose functionalities were 0.69 and 1.19 per a polymer unit, which were translated to be 1.73 and 2.49 mequiv/g in ion exchange capacity (IEC), respectively. These polymers showed excellent proton conductivity up to 2 × 10⁻¹ S/cm at 80 °C and 95% relative humidity.     

Structures and properties of highly sulfonated poly(arylenethioethersulfone)s as proton exchange membranes

A series of sulfonated poly(sulfonium cation) polymers, sulfonated poly(arylenethioethersulfone)s (SPTES)s possess up to two sulfonate groups per repeat unit, and can be easily converted into corresponding acid form of the SPTES polymer to form a tough, ductile, free-standing, pinhole-free membranes with excellent mechanical properties. The SPTES polymers exhibit good water affinity and excellent proton conductivity due to the high water uptake. Proton conductivities between 100 and 300 mS/cm (at 65 °C, 85% relative humidity) were observed for the SPTES polymers with 50 mol% (SPTES-50) to 100 mol% (SPTES-100) of sulfonated monomer. The evaluation by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermomechanical analysis (TMA) showed that the SPTES polymers have excellent thermal stability, mechanical properties, and dimensional stability, making them excellent candidates for the next generation of proton exchange membranes (PEMs) in fuel cell applications.     

Phosphonated poly(arylene ether)s as potential high temperature proton conducting materials

The preparation and characterization of new phosphonated polymeric ionomers based on a fully aromatic poly(arylene ether) backbone with applications as proton exchange membranes for fuel cell is reported. The high-molecular-weight polymers were obtained by the polycondensation of the phosphonated monomers with decafluorobiphenyl in high yields with inherent viscosities up to 0.58 dL g⁻¹. The hydrolysis of the phosphonated ester into phosphonic acid groups was carried out quantitatively under acidic conditions. The polymers were studied by TGA after hydrolysis and showed10% weight loss above 430 °C. Membranes with total ion-exchange capacities above 6 meq/g showed proton conductivities of approximately92 mS/cm at 25 °C and 100% relative humidity increasing to ca.150 mS/cm at 140 °C. Their conductivity under dry condition showed values over 2 mS/cm at 120 °C which upon doping with phosphoric acid jumped to nearly 100 mS/cm.     

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.     

Synthesis and characterization of sulfonated polyimides bearing sulfonated aromatic pendant group for DMFC applications

A novel side-chain-type sulfonated aromatic diamine, 5-[1,1-bis(4-aminophenyl)-2,2,2- trifluoroethyl]-2-(4-sulfophenoxy)benzenesulfonic acid (BABSA) was synthesized and characterized. Two series of sulfonated polymides (SPI-N and SPI-B) were prepared from 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA) or 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride (BNTDA), sulfonated diamine BABSA and various non-sulfonated aromatic diamines. The resulting sulfonated polyimide (SPI) membranes exhibited good dimensional stability with isotropic swelling of 7-22% and high thermal stability with desulfonation temperature of 283-330 °C. These membranes also displayed excellent oxidation stability and good water stability. The SPI membranes exhibited better permselectivity than Nafion 115 membrane due to their much lower methanol permeability. The ratios of proton conductivity to methanol permeability (Ф) for the SPI membranes were almost two to three times of that for Nafion 115. The SPI-N membranes exhibited excellent conducting performance with the proton conductivity higher than Nafion 115 as the temperature over 40 °C, which attributed to their good hydrophobic/hydrophilic microphase separation structure.     

Synthesis and properties of sulfonated aromatic fluoro‐polymers

Polycondensation of perfluorobiphenyl with α,α‐bis(4‐hydroxyphenyl)ethylbenzene and/or 9,9‐bis(4‐hydroxyphenyl)fluorene was investigated. The polycondensation of perfluorobiphenyl with α,α‐bis(4‐hydroxyphenyl)ethylbenzene and/or 9,9‐bis(4‐hydroxyphenyl)fluorene proceeded at low‐temperature to a give high‐molecular weight and thermal stable polymers. The ¹⁹F‐NMR spectra of the polymers indicate that the polymers consists of predominantly 1,4‐phenylene structure with respect to the perfluoro‐aromatic compound. The sulfonation of the polymers obtained from the polycondensation occurred at the phenyl groups and fluorenyl side chain. A tough and smooth film was prepared by a casting method from DMF solution of the sulfonated polymer. The films showed hydrolytic and oxidative stabilities, and a high‐proton conductivity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of novel sulfonated poly(phenylquinoxaline)s as proton exchange membranes

Two series of sulfonated poly(phenylquinoxaline)s (SPPQ-x and SPPQ(O)-x, x refers to molar percentage of sulfonated tetraamine monomer) were first synthesized from a sulfonated tetraamine (4,4′-bis(3,4-diaminophenoxy)biphenyl-3.3′-disulfonic acid) and two aromatic bisbenzils (4-phenylglyoxalylbenzil and p,p′-oxydibenzil) in a mild condition. The structures of SPPQ-x and SPPQ(O)-x were characterized by IR and ¹H NMR spectra. The properties of these polymer films, such as water uptake, water swelling ratio, proton conductivity, thermal properties, methanol permeability, hydrolytic and oxidative stability were also investigated. The resulting polymers generally showed good solubility in DMAc and DMSO. Flexible and tough membranes with high mechanical strength were prepared. They show very high thermal, thermooxidative, hydrolytic stabilities and low methanol permeability. SPPQ-100 with the IEC value (2.41 mmol/g) displays the conductivity of 0.1 S/cm and a swelling ratio of 7.3% at 100 °C. The low swelling was attributed to the high rigid of polymer backbones and the strong intermolecular interaction between the basic nitrogen atoms of quinoxaline units and sulfonic acid groups. Moreover, we found that the conductivities of SPPQ(O)-x membranes were higher than SPPQ-x membranes at the similar IEC value. The highest conductivity of 0.2 S/cm was obtained for SPPQ(O)-100 at 140 °C. A combination of excellent dimensional and hydrolytic stabilities indicated that the SPPQ ionomers were good candidate materials for proton exchange membrane in fuel cell applications.     

Study of the incorporation of protic ionic liquids into hydrophilic and hydrophobic rigid-rod elastomeric polymers

A series of polymers was synthesized that contain a rigid aromatic backbone connected through triazine linkages that are cross-linked by flexible diamine-terminated poly(ethylene oxide) oligomers. Polymers were made that contained both hydrophilic sulfonated aromatic and hydrophobic pyridinium triflate backbones. Thermal and mechanical properties of the resulting polymer films were studied, as well as uptake of water and protic ionic liquids. Ionic liquid uptake varied from 41 to 440%, depending upon the nature of the polymer. The ionic liquid-doped films were analyzed for proton conductivity at high temperatures (>150 °C) under non-humidified conditions. Conductivities as high as 5×10⁻² S/cm were observed at 150 °C.     

Synthesis and characterization of a new type of sulfonated poly(ether ether ketone ketone)s for proton exchange membranes

A novel series of sulfonated poly(ether ether ketone ketone)s (SPEEKKs) were prepared by aromatic nucleophilic polycondensation with different ratios of 1,3‐bis(3‐sodium sulfonate‐4‐fluorobenzoyl)benzene to 1,3‐bis(4‐fluorobenzoyl)benzene. ¹H‐NMR spectroscopy was used to confirm the degrees of sulfonation (DS) of the polymers. Thermal stabilities of the SPEEKKs in acid form were characterized by thermogravimetric analysis (TGA), which showed that SPEEKKs were excellently thermally stable at high temperatures. SPEEKK polymers can be easily cast into tough membranes. Both of proton conductivity and methanol diffusion coefficient have been tested in this article. Other properties of the SPEEKK membranes were investigated in detail. The results show that the SPEEKK membranes are promising in proton exchange membrane fuel cells (PEMFCs) application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

On the Stability of Selected Monomeric and Polymeric Aryl Sulfonic Acids on Heating in Water (Part 1)

A number of low molecular weight sulfonated aromatic compounds: carboxamides, imides, sulfonamides, as well as sulfonated polymers; aramides and poly(styrene‐p‐sulfonic acid), were tested for their stability on heating in water and dilute acid to temperatures ranging from 130–200 °C. Desulfonation was observed with some compounds. Sulfonamide linkages were found to be stable, while carboxamide linkages and phthalimides were not.     

一种新型磺化聚酰亚胺质子交换膜的合成与表征

质子交换膜是质子交换膜燃料电池膜电极的核心部件之一,它的性能好坏对整个系统的运行起着至关重要的作用．目前在质子交换膜燃料电池中普遍采用的质子交换膜材料是全氟磺酸系列薄膜,这类材料具有较高的质子传导率、化学及机械稳定性,但用于直接甲醇燃料电池（DMFC）时则存在甲醇渗透、导致燃料电池输出性能大大降低的问题