Sulfonated Polyetherimide and Its Membranes

Polyetherimide(PEI) was sulfonated by chlorosulfonic acid for the first time. The sulfonated products were characterized by FT-IR, DSC, ion exchange capacity and water sorption measurement. The hydrophilicity of PEI was improved by the sulfonation. The PEI was blended with the sodium salt from of sulfonated PEI(SPEI) to prepare microporous membranes. The morphologies of the membranes were studied with Scanning Electron Microscope (SEM).     

Synthesis and properties of sulfonated poly(arylene ether) containing tetraphenylmethane moieties for proton‐exchange membrane

A novel sulfonated poly(arylene ether) containing tetraphenylmethane moieties was successfully synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place only at the para position on the pendant phenyl rings because of the specially designed parent polymer. The sulfonation degree can be easily controlled by using different ratios of sulfonation agent to polymer repeating unit. The position and degree of sulfonation were characterized by ¹H NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N′‐dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton's reagent test revealed that the membrane exhibited superior stability to oxidation. The proton conductivities of the films were determined to be equivalent with Nafion® 117 under same conditions. The new polymer with sulfonic acid function on pendent phenyl rings can be potentially used as a proton‐exchange membrane for polymer electrolyte membrane fuel cell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6411–6418, 2005     

SYNTHESIS AND PROPERTIES OF SULFONATED POLY（ARYLENE ETHER） CONTAINING TRIPHENYL METHANE MOIETIES FROM ISOCYNATE MASKED BISPHENOL

A novel sulfonated poly（arylene ether） containing triphenylmethane moieties was synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place at the para position of the pendant phenyl rings because of the specially designed parent polymer. The position and degree of sulfonation were characterized by ^1H-NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N＇-dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton＇s reagent test revealed that the films exhibited superior stability to oxidation. The proton conductivities of the films were comparable with Nation 117 under same conditions. The membrane electrode assembly （MEA） prepared with the asmade film （706 EW, 100 μm dry thickness） shows better cell performance than Nation 115-MEA in the whole current density range.     

燃料电池质子交换膜用新型磺化聚芳醚酮的合成和性能表征

报道了一种新型磺化聚芳醚酮材料的合成方法, 通过引入取代基对聚芳醚主链进行保护，用氯磺酸直接磺化方法在聚芳醚酮高分子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酮. 通过核磁共振(NMR)、 热重(TG)和凝胶渗透色谱(GPC)等分析方法对其结构及性能进行了表征. 用溶液浇膜法制备了质子交换膜, 考察了膜的各种性能, 并与商用Nafion膜进行了比较, 其导电性、 热稳定性和吸水性远优于Nafion膜, 抗氧化性、抗水解性和机械强度也达到了较高的指标.     

Sulfonated poly(fluorenyl ether) membranes containing perfluorocyclobutane groups for fuel cell applications

This paper describes the preparation and electrochemical properties of new proton conducting polymer membranes, sulfonated poly(fluorenyl ether) membrane-containing perfluorocyclobutane (PFCB) moieties for fuel cell applications. The sulfonated polymers were prepared via thermal cyclodimerization of 9,9-bis(4-trifluorovinyloxyphenyl)fluorene and subsequent post-sulfonation using chlorosulfonic acid (CSA) as a sulfonating agent. The post-sulfonation reaction was carried out by changing the molar ratio of CSA/repeating unit of the polymer at room temperature for 5 h and the resulting sulfonated polymers showed different degrees of sulfonation (DS) and ion exchange capacities (IEC). With the increment of CSA content, the DS, IEC and water uptake of the sulfonated polymer membranes increased. Their proton conductivity was investigated as a function of temperature. The polymer membrane with an IEC value of 1.86 mmol/g showed a water content of 25% similar to Nafion-115's but showed higher proton conductivity than Nafion-115 over the temperature 25–80 °C. The polymer membrane with lower water uptake and higher IEC showed similar proton conductivity and methanol permeability to Nafion-115. These results confirmed that the sulfonated poly(fluorenyl ether)-containing PFCB groups could be a promising material for fuel cell membranes.     

Influence of blend miscibility on the proton conductivity and methanol permeability of polymer electrolyte blends

The influence of miscibility on the transport properties of polymer electrolyte blends composed of a proton conductor and an insulator was investigated. The proton‐conductive component in the blends was sulfonated poly(ether ketone ketone) (SPEKK), while the nonconductive component was either poly(ether imide) (PEI) or poly(ether sulfone) (PES). The phase behavior of PEI‐SPEKK blends was strongly influenced by the sulfonation level of the SPEKK. At low sulfonation levels (ion‐exchange capacity (IEC) = 0.8 meq/g), the blends were miscible, while at a slightly higher level (IEC = 1.1 meq/g), they were only partially miscible and for IEC ≥ 1.4 meq/g they were effectively immiscible over the entire composition range. The PES‐SPEKK blends were miscible over the entire range of SPEKK IEC considered in this study (0.8–2.2 meq/g). At high IEC (2.2 meq/g) and at low mass fractions of SPEKK (<0.5), the miscible blends (PES‐SPEKK) had higher proton conductivities and methanol permeabilities than the immiscible ones (PEI‐SPEKK). The opposite relationship was observed for high mass fractions of SPEKK (>0.5). This behavior was explained by the differences in morphology between these two blend systems. At low IEC of SPEKK (0.8 meq/g), where both PEI‐SPEKK and PES‐SPEKK blend systems exhibited miscibility, the transport properties were not significantly different. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2253–2266, 2006     

酸碱型磺化聚芳醚腈酮质子交换膜材料的性能研究

以合成的一系列不同磺化度的碘化聚芳醚腈酮(SPPENKs)为acidic聚合物,以聚芳醚酰亚胺(PEI)为basic聚合物,并将其溶解在N-甲基-2-吡咯烷酮(NMP)中配成质量分数为10%的成膜液,60℃下刮制成膜,制得acid-base型磺化聚芳醚腈酮质子导电了聚合物膜.用红外(FT-IR)谱图表征了acid-base型质子导电聚合物的结构,并测试了acid-base型质子导电聚合物膜的溶胀率、含水率、水解、氧化和热稳定性以及膜材料的离子交换容量IEC(IEC=meqSO3H/gdrymembrane)值等.测试结果初步表明新型质子导电聚合物膜具有良好的物化性能和较高的质子导电性,在80℃下acid-base型质子导电聚合物膜的水解断裂时间除SPPENK-40/PEI外,都超过2000h;SPPENK-60/PEI和SPPENK-80/PEI膜(IEC分别为1·08mmol/g、1·32mmol/g)与Nafion117相比,在具有较高质子交换能力的同时具有较低的溶胀率。     

侧基磺酸型含氟聚芳醚的合成

考察了多种高含氟量聚芳醚的磺化反应, 发现苯侧基的聚芳醚具有磺化反应条件简单, 磺化点与磺化度可控, 同时, 对其与质子交换膜材料相关的基本性能进行了表征.     

Novel UV‐induced photografting process for preparing poly(tetrafluoroethylene)‐based proton‐conducting membranes

A novel process comprising the UV‐induced photografting of styrene into poly(tetrafluoroethylene) (PTFE) films and subsequent sulfonation has been developed for preparing proton‐conducting membranes. Although under UV irradiation the initial radicals were mainly generated on the surface of the PTFE films by the action of photosensitizers such as xanthone and benzoyl peroxide, the graft chains were readily propagated into the PTFE films. The sulfonation of the grafted films was performed in a chlorosulfonic acid solution. Fourier transform infrared and scanning electron microscopy were used to characterize the grafted and sulfonated membranes. With a view to use in fuel cells, the proton conductivity, water uptake, and mechanical properties of the prepared membranes were measured. Even through the degree of grafting was lower than 10%, the proton conductivity in the thickness direction of the newly prepared membranes could reach a value similar to that of a Nafion membrane. In comparison with γ‐ray radiation grafting, UV‐induced photografting is very simple and safe and is less damaging to the membranes because significant degradation of the PTFE main chains can be avoided. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2624–2637, 2007     

Electrical properties of sulfonated polyether ether ketone/polyetherimide blend membranes doped with inorganic acids

The influence of blending with polyetherimide (PEI) and doping with HCl and H₃PO₄ on the properties of sulfonated polyether ether ketone (SPEEK) was studied. Blending with PEI first results in an increase and then in a decrease in membrane swelling at PEI concentrations greater than 5%. The electrical conductivity of blend membranes follows the same trend. Doping with the acids enhances the conductivity several times, and the effect of doping with HCl is more significant. PEI forms spherical particles dispersed in the SPEEK matrix and, at the same time, partially dissolves in SPEEK, which reduces the swelling of the matrix at higher PEI concentrations. The increase in the membrane capacity to absorb water at small PEI contents is due to the formation of new water adsorption sites along the interface between the particles and the matrix. A modified effective medium model yielded calculated results in good agreement with the measured conductivity values, when the experimental absorption data were used in the simulation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1386–1395, 2000     

Studies on synthesis and property of novel acid-base proton exchange membranes

Sulfonated poly(phthalazinone)s (SPPENK, SPPESK and SPPBEK) were prepared by direct polymerization reaction from sulfonated monomers. The novel acid-base membranes were composed of sulfonated polymers as the acidic compounds, and polyetherimide (PEI) as the basic compounds, casting from their N-methylpyrrolidone (NMP) solution directly onto clean glass plates at 60℃ aiming at enhancing membrane toughness and other relative properties. The resulted acid-base composite membranes had excellent resistance to swelling, thermo-stability, hydrolysis resistance and oxidative resistance properties with highly ion-exchange capacity (IEC).     

Pervaporation separation of water/ethanol mixture by sulfonated polysulfone membrane

For dehydrating a water/ethanol mixture by pervaporation, a sulfonated polysulfone membrane was prepared. The separation performance of water and ethanol are shown to strongly depend on the degree of substitution of polysulfone membrane. The degree of substitution increased with increasing chlorosulfonic acid in the casting solution, and the substitution reaction was achieved within 2 h. The water permeation rate and separation factor increased with increasing substitution of polysulfone membrane up to a substitution of 2.0. The effect of sulfonation on separation performance was due to the improvement of hydrophilicity of sulfonated membrane. It was found that the solubility of water/ethanol in the membrane was not the dominant factor for separation but it was rather the diffusion difference in the membrane. The diffusion difference between permeate through sulfonated membrane was the dominant factor for separating the water/ethanol mixture. The high performance of pervaporation membrane can be prepared by sulfonated polysulfone.     

Electrochemical methanol reformation (ECMR) using low-cost sulfonated PVDF/ZrP membrane for hydrogen production

Polymer electrolyte membrane (PEM)-based electrochemical methanol reformation has gained interest as a practical way to produce hydrogen than water electrolysis due to its low operating voltages. Development of alternative PEM for this application is of considerable interest in order to reduce the cost as well as increase the system efficiency. Presently, a novel SPVDF/ZrP composite membrane was synthesized as proton exchange membrane for hydrogen production using electrochemical methanol reformation (ECMR). PVDF-co-HFP granules were defluorinated by alkali treatment followed by sulfonation using chlorosulfonic acid to prepare sulfonated polymer. Inorganic zirconium phosphate (ZrP) was further added to increase proton conductivity. The membranes were characterized for their physicochemical properties, mechanical strength, and thermal stability. The enhancement in proton exchange capacity and water uptake with adequate dimensional stability was observed with dehydrofluorination and impregnation of ZrP. A novel electrolyzer consisting of Pt-Ru/C as anode electrode, same format as anode as cathode electrode and the SPVDF/ZrP composite membrane was assembled and its performance was tested for hydrogen production. It was found that SPVDF/ZrP composite membrane showed good electrochemical cell performance of 0.65 V at 0.15 A cm^?2 current density at ambient temperature and gives scope for operating ECMR cell at higher current densities for to increase the hydrogen production rate which is comparable to the performance of commercial Nafion^® 117 membrane.     

Sulfonated poly(phenylene oxide) membranes as promising materials for new proton exchange membranes

Poly(phenylene oxide) (PPO) was sulfonated to different ion exchange capacities (IECs) using chlorosulfonic acid as the sulfonating agent. Tough, ductile films were successfully cast from sulfonated PPO (SPPO) solutions in N‐methyl‐2‐pyrrolidone or N,N‐dimethylformamide. The obtained membranes had good thermal stability revealed by thermogravimetric analysis (TGA). Compared with an unsulfonated PPO membrane, the hydrophilicity and water uptake of the SPPO membranes were enhanced, as shown by reduced contact angles with water. The tensile test indicated that the SPPO membranes with IEC ranging from 0.77 to 2.63 meq/g were tough and strong at ambient conditions and still maintained adequate mechanical strength after immersion in water at room temperature for 24 hr. The results of wide‐angle X‐ray diffraction (WAXD) showed amorphous structures for PPO and SPPO while the peak intensity decreased after sulfonation. The proton conductivity of these SPPO membranes was measured as 1.16 × 10^?2 S/cm at ambient temperature, which is comparable to that of Nafion 112 at similar conditions and in the range needed for high‐performance fuel cell proton exchange membranes. Copyright © 2006 John Wiley & Sons, Ltd.     

Energy material - the role of silicotungstic acid and fly ash in sulfonated poly (ether sulfone) composites for PEMFC applications

The composite polymer electrolyte membranes were prepared from sulfonated poly (ether sulfone) (SPES), silicotungstic acid (STA) and fly ash (FA). Post sulfonation process was adopted to synthesize SPES using sulphuric and chlorosulfonic acid. The prepared electrolyte membranes were examined by water uptake capacity, swelling ratio, ion-exchange ability, proton conductivity, thermal stability and electrochemical performance for evaluating the pertinence of these membranes in fuel cell applications. As such the pristine membrane restricts with the proton conductivity of 0.042?S cm^?1 at 30?°C and 0.060?S cm^?1 at 90?°C while the polymer composite membrane, SP-STA-FA-10 reveals the maximum conductivity of 0.054?S cm^?1 at 30?°C and 0.073?S cm^?1 at 90?°C. It also exhibits good thermal stability than that of the pure membrane. The membrane electrode assemblies (MEAs) have been successfully developed from SPES as well as SP-STA-FA-10 membranes and their electrochemical performance were studied the wide range of current density. Herein, the composite membranes derived from SPES, STA and FA can be viable candidates for fuel cell applications.     

Synthesis and characterisation of novel functional polyolefin containing sulfonic acid groups

The strong polar group, sulfonic acid, has successfully been introduced into ethylene/allylbenzene copolymers without degradation or crosslinking via chlorosulfonation reaction with chlorosulfonic acid as a chlorosulfonating agent in 1,1,2,2-tetrachloroethane followed by hydrolysis. The degree of sulfonation (DS) can be easily controlled by changing the ratio of chlorosulfonic acid to the pendant phenyls of the copolymer. The microstructure of sulfonated copolymers were unambiguously revealed by ¹H NMR and ¹H-¹H COSY spectral analyses, which indicates that all the sulfonation reactions exclusively took place at the para-position of the aromatic rings. The thermal behaviors were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC data exhibit a systematic trend of melting temperature increasing with DS. TGA data of sulfonated copolymers show an increase in degradation temperature from 444 to 460 °C compared to the received copolymer. Sulfonated copolymers also show an additional minor loss of mass at approximately 261 °C, which is not observed in the received copolymer. The wetting properties of the sulfonated copolymers were also evaluated by contact angle measurement, and a notable increase in surface hydrophilicity was identified.     

Electrochemical and structural characterization of sulfonated polysulfone

We describe the synthesis, as well as the electrochemical and structural characterization, of sulfonated polysulfone intended for use in PEM fuel cells. Starting from a commercial polysulfone, we assessed the performance of these prepared ionomers using synthesis protocols compatible with industrial production. The efficiency of the trimethylsilyl chlorosulfonate and chlorosulfonic acid reagents in the sulfonation process was confirmed by ¹H NMR, FTIR, elemental analysis, chemical titration and thermal analysis (DSC and TGA). Chlorosulfonic acid was the most effective sulfonation reagent. However, based on SEC-MALLS, this reagent induced degradation of the backbone that is detrimental to the thermomechanical stability and lifespan of the membranes. The electrical characterization of the membranes was undertaken using impedance spectroscopy in contact with different HCl aqueous solutions at various temperatures. The activation energies, which ranged from 8.2 to 11 kJ/mol, were in agreement with the prevailing proton vehicular mechanism.     

Sulfonated poly(fluorene-co-sulfone)ether membranes containing perfluorocyclobutane groups for fuel cell applications

A new class of sulfonated poly(fluorene-co-sulfone)ether membranes containing perfluorocyclobutane (PFCB) groups were synthesized and characterized in terms of their electrochemical properties as proton exchange membranes for fuel cells. Two monomers, 9,9-bis(4-trifluorovinyloxyphenyl)fluorene and 4,4′-sulfonyl-bis(trifluorovinyloxy)biphenyl were synthesized and statistically copolymerized by thermal [2π + 2π] cycloaddition to yield a series of polymers containing 0–60 mol% of fluorenyl content (PFS-X). The copolymers were then sulfonated using chlorosulfonic acid to afford five kinds of ionomers with different sulfonation levels (SPFS-X), which were cast into membranes and analyzed in terms of electrochemical properties. It was found that the ion exchange capacity (IEC), water uptake, proton conductivity and methanol permeability values of SPFS-X increased with the increment of the sulfonated fluorenyl content. The proton conductivities of SPFS-50 and -60 with high IECs and water uptake values were higher than those of Nafion-115 between 25 and 80 °C. The methanol permeability of SPFS-X was considerably lower than that of Nafion-115.     

Oxidatively stable and highly proton conductive membrane from poly(arylene ether)s containing biphenyl moiety as pendent groups

Novel poly(arylene ether)s with sulfonic acid groups attached onto pendent biphenyl rings were successfully synthesized by the nucleophilic displacement of aromatic dihalides with bisphenols in aprotic solvent in the present of excess potassium carbonate, followed by sulfonation with chlorosulfonic acid. The sulfonation took place only on the pendent biphenyl rings due to the specially designed molecular structure. The sulfonated polymers were very soluble in common organic solvents, such as dimethyl sulfoxide, N,N′-dimethylacetamide, dimethylformamide, and can be readily cast into tough and smooth films. These membranes showed excellent stabilities resistance to both oxidation and hydrolysis, as evidenced by subjecting to both Fenton's reagent test and immersion in boiling water. The proton conductivities (3.2 × 10⁻³ S cm⁻¹) of the as-made membranes were higher than that of Nafion^® 117 (1.9 × 10⁻³ S cm⁻¹) under same conditions. The satisfied properties of these new polymers demonstrated them as promising candidates for proton exchange membrane in PEM fuel cell applications.     

Cellulose acetate and polyetherimide blend ultrafiltration membranes: II. Effect of additive

Ultrafiltration membranes are largely applied in the separation of heavy metal ion and macromolecular solutes from aqueous streams. Studies are presented on ultrafiltration blend membranes, based on cellulose acetate (CA) and polyetherimide (PEI) in various blend compositions. Polyethylene glycol (PEG 600) was employed as a non‐solvent additive in various concentrations to the casting solution to improve the ultrafiltration performance of the resulting membranes. The blend membranes prepared were characterized in terms of compaction time, pure water flux (PWF), water content, membrane resistance, and scanning electron microscopy (SEM). The molecular weight cut‐off (MWCO) obtained from the protein separation studies is also reported. Applications of these membranes for separating toxic metal ions from aqueous streams are discussed. Copyright © 2007 John Wiley & Sons, Ltd.