Synthesis and properties of novel sulfonated polyimides bearing sulfophenyl pendant groups for polymer electrolyte fuel cell application

A novel sulfonated diamine bearing sulfophenyl pendant groups of 2,2′-(4-sulfophenyl) benzidine (BSPhB) was synthesized. Sulfonated polyimides (SPIs) derived from 1,4,5,8-naphthalene tetracarboxylic dianhydride, BSPhB and other non-sulfonated diamines were successfully synthesized. The SPIs with ion exchange capacity (IEC) of 1.5-2.8 meq g⁻¹ showed high reduced viscosity of 3-10 dL g⁻¹ and high desulfonation temperature of 320 °C. The SPI membranes were tough and flexible, having high stress at break of more than 80 MPa and elongation of 80-100%. They showed highly anisotropic membrane swelling in water with larger swelling in thickness direction than in plane direction. They showed fairly high proton conductivity (σ). For example, the membrane with IEC of 1.77 meq g⁻¹ exhibited σ values of 120 and 260 mS cm⁻¹ at 60 and 120 °C, respectively, in water. They also showed fairly high water stability.     

Synthesis and characterization of novel sulfonated polyimides from 1,4-bis(4-aminophenoxy)-naphthyl-2,7-disulfonic acid

A novel sulfonated diamine monomer, 1,4-bis(4-aminophenoxy)-naphthyl-2,7-disulfonic acid (BAPNDS), was synthesized. A series of sulfonated polyimide copolymers were prepared from BAPNDS, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and nonsulfonated diamine 4,4′-diaminodiphenyl ether (ODA). Flexible, transparent, and mechanically strong membranes were obtained. The membranes displayed slightly anisotropic membrane swelling. The dimensional change in thickness direction was larger than that in planar. The novel SPI membranes showed higher conductivity, which was comparable or even higher than Nafion 117. Membranes exhibited methanol permeability from 0.24 × 10⁻⁶ to 0.80 × 10⁻⁶ cm²/s at room temperature, which was much lower than that of Nafion (2 × 10⁻⁶ cm²/s). The copolymers were thermally stable up to 340 °C. These preliminary results have proved its potential availability as proton-exchange membrane for PEMFCs or DMFCs.     

Synthesis, proton conductivity and methanol permeability of a novel sulfonated polyimide from 3-(2′,4′-diaminophenoxy)propane sulfonic acid

A novel sulfonated diamine monomer, 3-(2′,4′-diaminophenoxy)propane sulfonic acid (DAPPS), was successfully synthesized and the sulfonated polyimide (SPI) was prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and DAPPS. The resulting SPI, NTDA-DAPPS, was soluble in common organic solvents. The SPI membrane displayed proton conductivity σ values of 0.12-0.35 S/cm at temperatures ranging from 35 to 90 °C in liquid water, which were similar to or higher than those of Nafion 117 and sulfonated hydrocarbon polymers. The σ of the SPI membrane decreased significantly with decreasing relative humidity (RH) and became much lower than that of Nafion 117 at 30% RH. The SPI membrane displayed good water stability at 80 °C and was thermally stable up to 240 °C. It showed reasonable mechanical strength of a modulus of 1.3 GPa at 90 °C and 90% RH. Its methanol permeability P_M was 0.57×10⁻⁶ cm²/s at 30 °C and 8.6 wt% methanol in feed, which was a fourth of that of Nafion 117. As a result, its ratio of σ/P_M was 21×10⁴ S cm⁻³ s, which was about 4 times larger than that of Nafion 117, suggesting potential application of the SPI membrane for direct methanol fuel cell.     

Synthesis and properties of novel sulfonated polyimides bearing sulfophenyl pendant groups for fuel cell application

A novel sulfonated diamine bearing sulfophenyl pendant groups, namely, 4,4′-bis (4-aminophenoxy)-3,3′-bis(4-sulfophenyl) biphenyl and a series of sulfonated polyimides (SPIs) based on it were successfully synthesized. The SPIs had high viscosity and gave tough, flexible and transparent membranes. The SPI membranes showed anisotropic membrane swelling in water with 2.5-4 times larger swelling in thickness direction than in plane one. They displayed reasonably high proton conductivity. For example, the conductivities for the SPI with an ion exchange capacity of 1.80 mequiv/g were 104 and 7.3 mS/cm in water and 50% RH, respectively, at 60 °C. They maintained high mechanical strength and proton conductivity even after aging in water at 130 °C for 500 h, showing the high water stability comparable to the best SPI reported so far. In polymer electrolyte fuel cells (PEFCs) operated at 90 °C and 50% RH, they showed fairly high cell performances and have high potential for PEFC applications.     

Synthesis of novel bisphenol containing phthalazinone and azomethine moieties and thermal properties of cured diamine/bisphenol/DGEBA polymers

A novel bisphenol(1,2-dihydro-2-(4-((4-hydroxy)phenyliminomethylidene)phenyl)-4-(4-((4-(4-hydroxy)phenyliminomethylidene)phenoxy)phenyl)(2H)phthalazin-1-one, DPP) and a diamine(1,2-dihydro-2-(4-aminophenyl)-4-(4-(4-aminophenoxy)phenyl)(2H)phthalazin-1-one, DAP) were synthesized and characterized. The novel epoxy polymers containing phthalazinone and/or azomethine moieties were prepared by binary polymerization of DAP (or DPP) with diglycidyl ether of biphenyl A (DGEBA) and ternary polymerization of hybrid curing agents, DAP/DPP (DAP and DPP under different molar ratios) with DGEBA. The cure behaviors of these new epoxy systems were studied by dynamic differential scanning calorimeter (DSC) and Infrared (IR) scans. Especially, the activation energy of DAP/DGEBA calculated by Kissinger and Ozawa methods were 73.8 and 77.4 kJ/mol, respectively. For ternary epoxy system, it was found that hybrid curing agents of DAP/DPP exhibited significant associated effect on their reactivity towards the oxirane group. Glass transition temperatures (T_g's) of these new epoxy polymers were all above 150 °C from the results of DSC, and the initial thermal decomposition temperatures (T_d,5%'s) and integral procedure decomposition temperatures (IPDT's) of these new epoxy polymers are above 350 and 850 °C, respectively from results of thermogravimetric analyses (TGA). These results show that new epoxy polymers containing phthalazinone and/or azomethine moieties exhibited excellent thermal properties. Especially, thermal properties of the ternary epoxy polymers could be modified by changing the content of DAP and DPP. The linear relationships between char yield (Y_c,wt%) and the structural compositions of these new polymers (weight percentage of phthalazinone, azomethine and nitrogen, C/H weight ratio) were built.     

Water resistant sulfonated polyimides based on 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride (BNTDA) for proton exchange membranes

A series of sulfonated polyimides (SPIs) were synthesized in m-cresol from 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride (BNTDA), 4,4′-diaminodiphenylether-2,2-disulfonicacid (ODADS), and 4,4′-diamino-diphenyl ether (ODA) in the presence of triethylamine and benzoic acid. The resulted polyimides showed much better water resistance than the corresponding sulfonated polyimides from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and ODADS, which is contributed to the higher electron density in the carbonyl carbon atoms of BNTDA. Copolyimides S-75 and S-50 maintained their mechanical properties and proton conductivities after aging in water at 100 °C for 800 h. The proton conductivity of these SPIs was 0.0250-0.3565 S/cm at 20 °C and 100% relative humidity (RH), and increased to 0.1149-0.9470 S/cm at 80 °C and 100% RH. The methanol permeability values of these SPIs were in the range of 0.99-2.36 × 10⁻⁷ cm²/s, which are much lower than that of Nafion 117 (2 × 10⁻⁶ cm²/s).     

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.     

A covalent organic/inorganic hybrid proton exchange polymeric membrane: synthesis and characterization

Commercial polyetheretherketone (Victrex PEEK) was sulfonated up to 90% degree of sulfonation (DS), then reacted with SiCl₄ to obtain a hybrid polymer. The product was characterized by ²⁹Si NMR and ATR/FTIR spectroscopies demonstrating the formation of covalent bonds between the organic and inorganic components. No dispersed inorganic silicon was present in the product as evidenced by the lack of any resonance at δ<−100 ppm. Despite the high DS the physicochemical properties of the hybrid were suitable for the preparation of membranes exhibiting high and stable conductivity values (10⁻² S/cm), hence suitable for application as ion exchange membrane.     

Polymer electrolyte fuel cells based on main-chain-type sulfonated polyimides

Main-chain-type sulfonated polyimides (SPIs) from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid (BAPBDS) and 4,4′-bis(4-aminophenoxy)biphenyl (BAPB) were used as electrolyte membranes for polymer electrolyte fuel cells (PEFCs). The SPI membranes swelled anisotropically in water by four to five times more largely in thickness direction than in plane direction of membrane. The cells with the SPI membranes showed excellent polarization performances, which were a little better than that for Nafion 112, i.e., using highly humidified H₂ and O₂ gases with a pressure of 0.3 MPa, the cell voltages with current densities of 0.5 and 1 A/cm² were 0.76 and 0.69 V, respectively, at 90 °C. The polarization performance was rather weakly dependent on the cell temperature and on the humidifier temperature. The cells showed good short-term stability up to 50 h. The proton conductivities in thickness direction of membrane were calculated from the membrane resistances evaluated from the complex impedance spectra of the operating cells. They were 0.24 and 0.16 S/cm for the homo- and co-SPI membranes (2/1 in molar ratio of BABPDS/BAPB), respectively. The SPI membranes were rather isotropic in relation to proton conductivity in spite of their anisotropic morphology.     

Synthesis and properties of lyotropic liquid crystalline copolyamides containing phthalazinone moiety and ether linkages

A series of aromatic copolyamides containing phthalazinone moiety and ether linkages were prepared from 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4-(aminophenoxyl)phenyl)](2H)phthalazin-1-one (DHPZ-DA), p-phenylenediamine (PPD), 4,4′-diaminodiphenylether (DAPE) and terephthaloyl dichloride (TPC) by low temperature solution polycondensation. The copolyamides had relatively high inherent viscosities, ranging from 1.86 to 5.30 dl/g. The copolyamides showed T_g values between 297 and 351 °C. Solubility of these copolyamides was improved in NMP, DMAc, NMP (1 wt% LiCl) and DMAc (1 wt% LiCl) by introducing phthalazinone moiety and ether linkages into the main chain. And they had good thermal stability, associated with 5 and 10% weight loss temperatures in the range of 480-516 and 501-532 °C in nitrogen, respectively. WAXD measures indicated these copolyamides were semicrystalline in nature. Some of these copolyamides exhibited lyotropic liquid crystalline behavior in concentrated H₂SO₄, NMP (1 wt% LiCl), and even in NMP solutions, as evidenced by polarizing light microscopy.     

Sulfonated polyimides bearing benzimidazole groups for proton exchange membranes

A series of sulfonated polyimides containing benzimidazole groups were synthesized using 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride (BTDA), 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS) as the sulfonated diamine, and 2-(3′,5′-diaminophenyl)benzimidazole (a) or 6,4′-diamino-2-phenylbenzimidazole (b) as the nonsulfonated diamine. The electrolyte properties of the synthesized polyimides (Ia − x, Ib − x, x refers to molar percentage of the sulfonated diamine) were investigated and compared with those of polyimides (Ic − x) from BTDA, ODADS, and m-phenylenediamine (c). All synthesized polyimides possessed high molecular weights revealed by their high viscosity, and formation of tough and flexible membranes. Polyimides with benzimidazole groups exhibited much better swelling capacity than those without benzimidazole groups. This was attributed to the strong interchain interaction through basic benzimidazole functions and sulfonic acid groups. The sulfonated polyimides that are incorporated with 1,1′,8,8′-binaphthalimide exhibited better hydrolytic stability than that with 1,4,5,8-naphthalimide. Polyimide membranes with good water stability as well as high proton conductivity were developed. Polyimide membrane (Ia − 90), for example, did not lose mechanical properties after being soaked in boiling water for 1000 h, while its proton conductivity was still at a high level (compared to that of Nafion 117).     

Synthesis,Characterization and Anti-Breast Cancer Activity of New 4-Aminoantipyrine-Based Heterocycles

4-Aminoantipyrine was utilized as key intermediate for the synthesis of pyrazolone derivatives bearing biologically active moieties. The newly synthesized compounds were characterized by IR, ¹H- and ¹³C-NMR spectral and microanalytical studies. The compounds were screened as anticancer agents against a human tumor breast cancer cell line MCF7, and the results showed that (Z)-4-((3-amino-5-imino-1-phenyl-1H-pyrazol-4(5H)-ylidene)methylamino)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 5, 3-(4-bromophenyl) -1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 13, 1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1-Hpyrazol- 4-yl)-3-(4-iodophenyl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 14, 3,3′-(4,4′-sulfonylbis(4,1-phenylene))bis(1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol- 4-yl)-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile) 16, (Z)-1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-hydrazono-4-oxo-3-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 17, (Z)-1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-4-oxo-3-phenyl-2-(2-phenylhydrazono)-1,2,3,4-tetrahydro pyrimidine-5-carbonitrile 18, and (Z)-4-(3-amino-6-hydrazono-7-phenyl-6,7-dihydro pyrazolo[3,4-d]pyrimidin-5-yl)-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 19 were the most active compounds with IC₅₀ values ranging from 30.68 to 60.72 μM compared with Doxorubicin as positive control with the IC₅₀ value 71.8 μM.     

一种新型的燃料电池用质子交换膜--磺化聚酰亚胺膜

综述了磺化聚酰亚胺作为质子交换膜燃料电池中膜材料的研究概况。介绍了其制备方法,总结了磺化聚酰亚胺结构对膜性能的影响。重点讨论了提高磺化聚酰亚胺质子交换膜电导率的途径和影响水解稳定性的因素,结果表明：纳米孔和相分离结构有助于提高质子电导率;磺化聚酰亚胺的水解稳定性不仅与吸水率有关,还与分子链的柔性和二胺单体的碱性有关。     

Facile in situ template synthesis of sulfonated polyimide/mesoporous silica hybrid proton exchange membrane for direct methanol fuel cells

Highly conductive and hydration retentive organic-inorganic hybrid proton exchange membranes for direct methanol fuel cells were synthesized by in situ sol-gel generation of mesoporous silica (mSiO₂) in sulfonated polyimide (SPI) via self-assembly route of organic surfactant templates for the tuning of the architecture of silica. The microstructure and properties of the resulting hybrid membranes were extensively characterized. The mesopores of about 3 nm in silica dispersion phase were formed in the SPI matrix. The existence of the mesoporous structure of silica improved the thermal stability, water-uptake and proton conductivity as well as methanol resistance of the hybrid membranes. The hybrid membrane with 30 wt.% mSiO₂ exhibited the water-uptake of 44.8% at 25 °C, and proton conductivity of 0.214 S cm⁻¹ at 80 °C at RH = 100%, while pure SPI exhibited the values of 40.6% and 0.179 S cm⁻¹ in the same test conditions, respectively. The results suggested that the highly hydrophilic character of Si-OH groups and the large surface area of mSiO₂ should contribute to the improvement of the water-uptake, meanwhile the mesoporous channels may supply the continuous proton conductive pathway in the hybrid membranes.     

Direct synthesis of sulfonated poly(ether ether ketone ketone)s (SPEEKKs) proton exchange membranes for fuel cell application

A series of sulfonated poly(ether ether ketone ketone)s (SPEEKK)s based membranes have been prepared and evaluated for proton exchange membranes (PEM). The membranes show very good thermal and mechanical stabilities. The structures of membranes were studied with AFM. The membranes show very good proton conductive ability (25 °C: 0.007-0.04 s/cm) and methanol resistance (25 °C: 7.68×10⁻⁸ to 5.75×10⁻⁷ cm²/s). The methanol diffusion coefficients of membranes are much lower than that of Nafion (2×10⁻⁶ cm²/s). The SPEEKKs membranes show very good respective in direct methanol fuel cells (DMFC) usages.     

Synthesis of novel sulfonated polybenzimidazole and preparation of cross-linked membranes for fuel cell application

A novel sulfonated polybenzimidazole, sulfonated poly[2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (SOPBI), was successfully prepared by post-sulfonation reaction of the parent polymer, poly[2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (OPBI), using concentrated and fuming sulfuric acid as the sulfonating reagent at 80 °C, and the degree of sulfonation (DS) could be regulated by controlling the reaction conditions. No significant polymer degradation was observed in the post-sulfonation processes. Direct polymerization of 4,4′-dicarboxydiphenyl ether-2,2′-disulfonic acid disodium salt (DCDPEDS) and 3,3′-diaminobenzidine (DABz), however, resulted in insoluble gels either in polyphosphoric acid (PPA) or in phosphorus pentoxide/methanesulfonic acid (PPMA) in a ratio of 1:10 by weight reaction medium. The SOPBIs prepared by the post-sulfonation method showed good solubility in dimethyl sulfoxide (DMSO), high thermal stability, good film forming ability and excellent mechanical properties. Cross-linked SOPBI membranes were successfully prepared by thermal treatment of phosphoric acid-doped SOPBI membranes at 180 °C in vacuo for 20 h and the resulting cross-linked membranes showed much improved water stability and radical oxidative stability in comparison with the corresponding uncross-linked ones, while the proton conductivity did not change largely. Highly proton conductive (150 mS cm⁻¹, 120 °C in water) and water stable SOPBI membrane was developed.     

Synthesis and characterization of sulfonated bromo-poly(2,6-dimethyl-1,4-phenylene oxide)-co-(2,6-diphenyl-1,4-phenylene oxide) copolymer as proton exchange membrane

Novel polymer electrolyte membranes containing the sulfonic acid groups attached on polymer backbone and side group simultaneously were synthesized. The bromo-poly(2,6-dimethyl-1,4-phenylene oxide)-co-(2,6-diphenyl-1,4-phenylene oxide) copolymer (BrcoPPO) was prepared by oxidative coupling polymerization with 2,6-dimethyl phenol, 2,6-diphenyl phenol, CuCl(I) and pyridine, and followed by bromination with bromine. Copolymer was maintained in 2,6-diphenyl phenol 10 mol% and 2,6-dimethyl phenol 90 mol%. Sulfonation of BrcoPPO (S-BrcoPPO) was carried out in a chlorobenzene solvent using chlorosulfonic acid. The polymeric membranes were cast from dimethylsulfoxide solution. The membranes were studied by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. S-BrcoPPO membranes exhibited proton conductivities from 2.3 × 10⁻³ to 1.4 × 10⁻² S/cm, water uptake from 7.00 to 49.43%, IEC from 0.58 to 1.38 mequiv./g, methanol permeability from 1.9 × 10⁻⁷ to 3.5 × 10⁻⁷ cm²/S.     

Preparation and characterization of multilayer-type electrolyte membranes with hydrocarbon polymers

Multilayer-type polymer electrolyte membranes composed of a sulfonated poly(4-phenoxybenzoyl-1,4-phenylene) (S-PPBP) layer and a mono[poly(propylene oxide)methacrylate]phosphate ester (PPHP) layer were fabricated by solution-casting procedure (Method 1) and hot-pressing procedure (Method 2) in order to suppress methanol permeability of electrolyte membranes. No delamination was observed by SEM measurements of S-PPBP/PPHP interfaces, indicating that PPHP had good adhesive properties to S-PPBP surfaces. The methanol permeability of S-PPBP/PPHP membranes was lower than that of S-PPBP membranes and decreased with increasing the thickness of PPHP layers. The bilayer membrane with 12 μm PPHP and 40 μm S-PPBP layers showed a methanol permeability of 2.97 × 10⁻⁷ cm² s⁻¹ in 1 mol dm⁻³ methanol aqueous solution at 25 °C, which was 13% less than that of the S-PPBP membranes. The conductivity of this membrane reached its optimum with values as high as 1.57 × 10⁻¹ S cm⁻¹ at 80 °C and 90%RH.     

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     

Studies on anhydrous proton conducting membranes based on imidazole derivatives and sulfonated polyimide

Anhydrous proton conducting membranes based on sulfonated polyimide (sPI) and imidazole derivatives were prepared. The acid-base composite membranes show a good chemical oxidation stability and high thermal stability. The addition of imidazole derivatives in sPIs can improve the chemical oxidation stability of the composite membranes enormously, and even much better than that of pure sPI. The proton conductivity of a typical sPI/xUI(2-undecylimidazole) composite membrane can reach 10⁻³ S cm⁻¹ at 180 °C under the anhydrous condition. The proton conductivity of the acid-base composite membranes increases significantly with increasing content of UI. Moreover, UI in sPI/xUI composite membrane is difficult to be brought out by the vapor due to the existence of long hydrophobic moiety, which will improve the stability and lifetime of the membranes in the fuel cells.