Effect of PES on the morphology and properties of proton conducting blends with sulfonated poly(ether ether ketone)

Development of alternate materials to Nafion, based on ionically conducting polymers and their blends is important for the wider applications of proton exchange membrane fuel cells. In this work, blends of sulfonated poly(ether ether ketone) (SPEEK) with poly(ether sulfone) (PES) are investigated. SPEEK with various ion exchange capacity (IEC) was prepared and blended with PES, which is nonionic and hydrophobic in nature. A comparative study of the water uptake, proton conductivity, and thermo‐mechanical characteristics of SPEEK and the blend membranes as a function of the IEC is presented. Addition of PES decreases the water uptake and conductivity of SPEEK. Chemical and thermal stability and mechanical properties of the membrane improve with the addition of PES. The effect of water content on the thermo‐mechanical properties of membranes was also studied. The morphology of blend membranes was studied using SEM to understand the microstructure and miscibility of the components. On the basis of the results, a plausible microstructure of the blends is presented, and is shown to be useful in understanding the variation of different properties with blending. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

直接甲醇燃料电池用新型质子交换膜的研究

以聚醚醚酮(PEEK)为原料,浓硫酸为磺化剂制备了不同磺化度的磺化聚醚醚酮(SPEEK)膜,以及磺化聚醚醚酮与聚乙烯醇(PVA)、正硅酸乙酯(TEOS)、磷钨酸的复合膜.分别对膜的电导率、阻醇性能和吸水率进行了研究.随着SPEEK膜磺化度的增大,膜的电导率有所提高,然而甲醇渗透系数也增大,膜的机械强度明显降低.SPEEK膜的吸水率低于Nafion 115膜,而PVA膜的吸水率则过高.     

Effect of dispersion state of Cloisite15A® on the performance of SPEEK/Cloisite15A nanocomposite membrane for DMFC application

The introduction of 2,4,6‐triaminopyrimidine (TAP) into sulfonated poly(ether ether ketone) (SPEEK)/Cloisite15A® nanocomposite membranes were investigated for the purpose of maintaining low methanol permeability and suppressing swelling in direct methanol fuel cell (DMFC). SPEEK with 63% of degree of sulfonation (DS) was prepared by sulfonation of PEEK. Cloisite15A (7.5 wt %) along with various weight loading of TAP was incorporated into SPEEK matrix via solution intercalation method. The effect of TAP loading on the SPEEK/Cloisite15A/TAP morphology was studied. The beneficial impact of the SPEEK/Cloisite15A/TAP morphology on the physicochemical properties of the membrane was further discussed. Swelling behavior, ion exchange capacity (IEC), proton conductivity, and methanol permeability of the resultant membranes were determined as a function of Cloisite15A and TAP loadings. Uniform distribution of Cloisite15A particles in the SPEEK polymer matrix in the homogenous SPEEK/Cloisite15A/TAP nanocomposite membranes was confirmed by scanning electron microscopy and X‐ray diffraction. The water uptake of the SPEEK nanocomposite membranes decreased dramatically in the presence of TAP. The significant selectivity of SP/7.5/7.5 nanocomposite membranes could indicate a potential feasibility as a promising electrolyte for DMFC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Proton exchange membranes based on poly(vinylidene fluoride) and sulfonated poly(ether ether ketone)

Blend membranes were obtained by solution casting from poly(vinylidene fluoride) (PVDF) and sulfonated poly(ether ether ketone) (SPEEK) in N,N-dimethylacetamide (DMAc). DSC and XRD were used to characterize the structure of the blend membranes. The effect of PVDF content on the membrane properties was investigated. The methanol permeability, water uptake and the swelling ratio of blend membranes decreased with the increase of PVDF content. Though the proton conductivity decreased upon the addition of PVDF, they were still comparable to that of Nafion^® 117 membrane. Higher selectivities were also found for most blend membranes in comparison with Nafion^® 117 membrane. The effect of methanol concentration on solution uptake, swelling ratio and methanol permeability of the blend membranes was also studied.     

Modified Sulfonated Poly(ether ether ketone) Based Mixed Matrix Membranes for Direct Methanol Fuel Cells

Mixed matrix membranes based on zeolite 4A‐methane sulfonic acid (MSA)‐sulfonated poly(ether ether ketone) (SPEEK) are evaluated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cells (DMFCs). Ion‐exchange capacity, sorption of water, and water–methanol mixture, proton conductivity, and methanol permeability for the mixed‐matrix membranes have been extensively investigated. The mixed‐matrix membranes are also characterized for their cross‐sectional morphology, mechanical, and thermal properties. DMFCs employing SPEEK‐MSA (20 wt.%) blend, zeolite 4A (4 wt.%)‐SPEEK‐MSA (20 wt.%) mixed matrix membranes deliver peak power densities of 130 and 159 mW cm^–2, respectively; while a peak power density of only 95 mW cm^–2 is obtained for the DMFC employing pristine SPEEK membrane at 70 °C. The results showed that these SPEEK based mixed matrix membranes exhibit higher DMFC performance and lower methanol permeability in comparison to Nafion‐117 membrane.     

State of the water in crosslinked sulfonated poly(ether ether ketone)

We investigated the material properties of different crosslinked sulfonated poly(aryl ether ketone) membranes, focusing on the effect of the degree of sulfonation and crosslinking density on the water uptake, the physical state of the water, and the pore size distribution within the membranes. We observed that the degree of sulfonation and, in particular, the ion‐exchange capacity (IEC) had less effect on the control of the extent of water absorbed than the crosslinking density of the membranes. Crosslinking also enabled the membranes to reach a higher water contents without losing mechanical integrity. Moreover, increasing the crosslinking density resulted in the presence of more bound water, without dissolution of the membrane. The crosslinked membranes had lower methanol permeability and electroosmotic drag values. Only at low IEC values and low water uptake in partially crystalline sulphonated poly(ether ether ketone), SPEEK could the presence of nanometer pores in the water‐equilibrated crosslinked membranes be confirmed by thermoporometry and the pore size distributions were then comparable to those reported for Nafion membranes. At higher IEC values, the water uptake was extremely high, up to 300%, and then the structure of the swollen membranes was more analogous to that of a dilute aqueous solution of the sulfonated polymer, and no nanopores were present. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of microstructural functional polyaniline layers on SPEEK/HPW proton exchange membranes

In this study, a method is developed to fabricate sulfonated poly (ether ether ketone)/phosphotungstic acid‐polyaniline (SPEEK/HPW‐PANI) membranes by in situ polymerization of aniline for the purpose of decreasing the weight loss of HPW in the membranes. The synthesis involves the production of a SPEEK/HPW hybrid membrane followed by different layer of PANI coatings on the membrane surface, and subsequent treatment using drying in vacuum procedures. The scanning electronic microscopy images showed that HPW had good compatibility with SPEEK polymers and energy dispersive X‐ray spectroscopy revealed the successfully doping with HPW and polymerization of PANI. The surface of SPEEK/HPW‐PANI becomes more compact than that of SPEEK/HPW and pure SPEEK, which may lead to reduce the water uptake and swelling property. The proton conductivity was found for the SPEEK/HPW‐PANI‐5 composite membrane (91.53 mS/cm at 80°C) higher than that of pure SPEEK membrane (68.72 mS/cm at 80°C). Better thermal stability was determined in both SPEEK/HPW and SPEEK/HPW‐PANI membranes than pristine SPEEK membrane. Therefore, PANI is a good potential coating for organic–inorganic hybrid e.g. SPEEK/HPW membrane materials to improve their hydrothermal stable properties and SPEEK/HPW PANI is a material that shows promise as a proton exchange membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41033.     

Proton exchange composite membranes comprising SiO2, sulfonated SiO2, and metal–organic frameworks loaded in SPEEK polymer for fuel cell applications

Proton exchange membrane fuel cell (PEMFC) is a promising technology that offers a clean and efficient renewable energy source. The hybrid SiO₂, sulfonated SiO₂ (S SiO₂), and metal–organic framework-5 (MOF-5) incorporated sulfonated poly (ether ether ketone) (SPEEK) ternary composite membranes are fabricated using dry phase inversion technique for PEMFC. The membrane performance is evaluated in terms of water uptake, ion exchange capacity, methanol permeability, and proton conductivity (PC) measurements. The morphological study of fabricated membranes was carried out using scanning electron microscopy and atomic force microscopy analysis. The mechanical stability is strengthened up to 30–40%, and the PC gets enhanced with the incorporation of MOF-5, achieving simultaneous improvement in proton conduction and membrane stability. The PC of the ternary SPEEK/S SiO₂/MOF-5 membrane is 3.69 × 10⁻³ S cm⁻¹, 32% more than the neat membrane. A significant increase in selectivity of 23% is observed by incorporating S SiO₂ and MOF-5 fillers when compared with the neat membrane. The synergistic effect of MOF-5 and S SiO₂ in the ternary membrane has significantly improved water retention and proton conductivity. The functional  SO₃H groups of SiO₂ and MOF-5 bonded via acid–base electrostatic interactions with the SPEEK; enhances proton conduction accompanied by suppressing the methanol penetration through membranes.     

DMFCs用磺化聚醚醚酮/磺化酚酞型聚醚砜共混质子交换膜

A sulfonated poly(ether ether ketone) (SPEEK) membrane with fairly high degree of sulfonation (DS) swells excessively and even dissolves at high temperature. To solve these problems, sulfonated phenolphthalein poly(ether sulfone) (SPES-C, DS 53.7%) is blended with the SPEEK matrix (DS 55.1%, 61.7%) to prepare SPEEK/SPES-C blend membrane. The decrease in swelling degree and methanol permeability of the membrane is dose-dependent. Pure SPEEK (DS 61.7%) membrane dissolves completely in water at 70ºC, whereas the swelling degree of the SPEEK (DS 61.7%)/SPES-C (40%, by mass) membrane is 29.7% at 80ºC. From room temperature to 80ºC, the methanol permeability of all SPEEK (DS 55.1%)/SPES-C blend membranes is about one order of magnitude lower than that of Nafion®115. At higher temperature, the addition of SPES-C polymer increases the dimensional stability and greater proton conductivity can be achieved. The SPEEK (DS 55.1%)/SPES-C (40%, by mass) membrane can withstand temperatures up to 150ºC. The proton conductivity of SPEEK (DS 55.1%)/SPES-C (30%, by mass) membrane approaches 0.16 S•cm－1, matching that of Nafion115 at 140ºC and 100% RH, while pure SPEEK (DS 55.1%) membrane dissolves at 90ºC. The SPEEK/SPES-C blend membranes are promising for use in direct methanol fuel cells because of their good dimensional stability, high proton conductivity, and low methanol permeability.     

Proton conductivity and methanol permeability of sulfonated poly(vinyl alcohol) membranes modified by using sulfoacetic acid and poly(acrylic acid)

Sulfonated poly(vinyl alcohol) (PVA) for use as a proton conductive membrane in a direct methanol fuel cell (DMFC) was prepared by reacting the PVA with sulfoacetic acid and poly(acrylic acid). The effects of the amount of sulfoacetic acid and poly(acrylic acid) on proton conductivity, methanol permeability, water uptake, and ion exchange capacity (IEC) of the sulfonated PVA membranes were investigated by using impedance analysis, gas chromatography, gravimetric analysis, and titration techniques, respectively. The water uptake of the membranes decreased with the amount of the sulfoacetic acid and the amount of poly(acrylic acid) used. The proton conductivity and the IEC values of the membranes initially increased and then decreased with the amount of the sulfoacetic acid. The methanol permeability of the sulfonated PVA membranes decreased continuously with the amount of the sulfoacetic acid. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation of highly H+ permeable sulfonated poly(ether ether ketone) cation exchange membranes and their applications in electro‐generation of thioglycolic acid

BACKGROUND: Sulfonated poly(ether ether ketone) (SPEEK) was successfully synthesized from sulfonated 4,4′‐difluorobenzophenone, 4,4′‐difluorobenzophenone and bisphenol A. SPEEK cation exchange membranes were prepared by the casting method. The composition and morphology of SPEEK were characterized using Fourier transform infrared and ¹H NMR spectroscopies, respectively. The ion exchange capacity (IEC), water uptake and degree of swelling of the membranes were also investigated. SPEEK120 was used as a separator in an electrolysis cell to produce thioglycolic acid (TGA). RESULTS: SPEEK polymerization was carried out at 145 and 175 °C for 10 h. The IEC of the SPEEK membranes was measured as 0.24–2.02 meq g^?1 and the water uptake as 2.26–26.45%. The degree of swelling of the membranes was 1.71–15.28%. TGA was effectively prepared by electro‐reduction of dithioglycolic acid. The current efficiency peaked at 58.31% at room temperature with a current density of 15 mA cm^?2. CONCLUSION: SPEEK120 membrane shows good dimensional stability and H⁺ permeability. Compared to the traditional metal‐reduction method, the current electro‐reduction technique avoids the use of zinc powder and so reduces environmental pollution. Copyright © 2009 Society of Chemical Industry     

Sulfonated poly(ether ether ketone)/epoxy/phenol novolac blend proton‐exchange membranes with low methanol permeability

A crosslinked epoxy [4,4′‐diglycidyl‐(3,3′,5,5′‐tetramethylbiphenyl) epoxy resin (TMBP)], cured by phenol novolac (PN), was introduced into a sulfonated poly(ether ether ketone) (SPEEK) membrane (ion‐exchange capacity = 2.0 mequiv/g) with a casting‐solution, evaporation, and heating crosslinking method to improve the mechanical properties, dimensional stability, water retention, and methanol resistance. By Fourier transform infrared analysis, the interactions between the sulfonic acid groups and hydroxyl groups in the blend membranes were confirmed. The microstructure and morphology of the blend membranes were investigated with atomic force microscopy. As expected, the blend membranes showed excellent mechanical properties, good thermal properties (thermal stability above 200°C), lower swelling ratios (1.4% at 25°C and 7.0% at 80°C), higher water retention (water diffusion coefficient = 9.8 × 10^?6 cm²/s), and a lower methanol permeability coefficient (3.6 × 10^?8 cm²/s) than the pristine SPEEK membrane. Although the proton conductivity of the blend membranes decreased, a higher selectivity (ratio of the proton conductivity to the methanol permeability) was obtained than that of the pristine SPEEK membrane. The results showed that the SPEEK/TMBP/PN blend membranes could have potential use as proton‐exchange membranes in direct methanol fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The Preparation of Metal–Organic-Framework/Boron Phosphate Hybrid Materials for Improved Performances in Proton Exchange Membranes

New types of metal–organic framework based hybrid materials are designed and prepared, which involving the hybridization of various content of boron phosphate (BPO₄) with the precursor of HKUST-1. The structure of obtained HKUST-1/BPO₄ hybrid materials (HB) is fully investigated, and then applied to construct sulfonated poly (ether ether ketone) (SPEEK) based proton exchange membranes (SPEEK/HB). Owing to effective interactions between hybrid materials and SPEEK matrix, the achieved composite membranes reflect a considerable improvement in mechanical and thermal stability, oxidative stability, methanol permeation, and proton conductivity. In particular, the tensile strength of SPEEK/HB-20 composite membrane is 41.3 MPa, which is 1.5 times higher than pristine SPEEK, and the methanol permeability reduced to one-third of SPEEK at the same time. The SPEEK/HB-10 displays the highest proton conductivity of 37.4 mS cm⁻¹ at 80 °C, which is obviously higher than pristine SPEEK. These results reveal that the hybridization of HKUST-1 with BPO₄ provide a promising candidate in the modification of proton exchange membranes (PEMs), and this strategy also possess great application potential in other types of MOFs-based hybrid materials.     

Effects and properties of poly(arylene ether benzonitrile)s of various molecular weights blended with sulfonated poly(ether ether ketone)

Poly(arylene ether benzonitrile) (PAEBN) was synthesized with 2,6‐dichlorobenzonitrile and biphenol. PAEBNs with various molecular weights (MWs), 1,640,000 and 185,000 g/mol, were synthesized by control of the stoichiometry of the monomers and were blended with sulfonated poly(ether ether ketone) (SPEEK). The effects of MW on the water uptake, swelling, methanol permeability, and proton conductivity of the SPEEK/PAEBN blend membranes were investigated. The molecular mobility of the SPEEK/PAEBN blends was also examined in this study. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

DMFCs用SPEEK/SiOx-S复合质子交换膜

A sulfonated poly(ether ether ketone) (SPEEK) membrane with a fairly high degree of sulfonation (DS) can swell excessively and even dissolve at high temperature. To solve these problems, insolvable functionalized silica powder with sulfonic acid groups (SiOx-S) was added into the SPEEK matrix (DS 55.1%) to prepare SPEEK/ SiOx-S composite membranes. The decrease in both the swelling degree and the methanol permeability of the membranes was a dose-dependent result of addition of the SiOx-S powder. Pure SPEEK membrane swelled 52.6% at 80°C, whereas the SPEEK/SiOx-S (15%, by mass) membrane swelled only 27.3% at the same temperature. From room temperature to 80℃, all SPEEK/SPEEK/SiOx-S composite membranes had methanol permeability of about one order of magnitude lower than that of Nafion115. Compared with pure SPEEK membranes, the addition of the SiOx-S powder not only leads to higher proton conductivity, but also increases the dimensional stability at higher temperatures, and greater proton conductivity can be achieved at higher temperature. The SPEEK/SiOx-S (20%, by mass) membrane could withstand temperature up to 145°C, at which in 100% relative humidity (RH) its proton conductivity exceeded slightly that of Nafion115 membrane and reached 0.17 S•cm－1, while pure SPEEK mem-brane dissolved at 90°C. The SPEEK/SiOx-S composite membranes are promising for use in direct methanol fuel cells because of their good dimensional stability, high proton conductivity, and low methanol permeability.     

Study of high-temperature proton exchange membrane through one-step encapsulation of ionic liquid in sulfonated poly(ether ether ketone)

The proton exchange membrane (PEM) is the core component of a high-performance proton exchange membrane fuel cell (PEMFC). Since the traditional PEM has the disadvantages of poor cell performance and high cost, a new kind of PEM with good proton conductivity, low cost and simple preparation should be explored. In this paper, several different binary hybrid membranes were successfully prepared through one-step encapsulation of different ionic liquids (ILs) in sulfonated poly(ether ether ketone) (SPEEK). The prepared membranes were characterized by scanning electron microscope (SEM), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), proton conductivity measurements and dynamic mechanical analysis (DMA). SEM images showed that ILs were fully doped into SPEEK. FT-IR and XPS proved that SPEEK and IL formed a new chemical bond combined with intermolecular hydrogen bonds. The TG results showed that the binary hybrid membranes could maintain stability even at 300°C. The water uptake and swelling ratio showed that the water absorption capacity of the binary composite membrane played a vital role in improving proton conductivity. The proton conductivity study showed that ILs doping also helped to improve the proton conductivity of the SPEEK membrane. When the doping amount of IL was maintained at 30 wt.%, it has the highest proton conductivity, 25 mS cm⁻¹ at 120°C. It was proved that anhydrous hybrid membrane tetraphenyl imidazole sulfate/SPEEK ([IM2][H₂PO₄]/SPEEK) could be used in PEMFC at medium temperature.     

Novel polymer electrolyte membranes based on semi‐interpenetrating blends of poly(vinyl alcohol) and sulfonated poly(ether ether ketone)

In this work, the properties of novel ionic polymer blends of crosslinked and sulfonated poly(vinyl alcohol) (PVA) and sulfonated poly(ether ether ketone) (SPEEK) are investigated. Crosslinking and sulfonation of PVA were carried out using sulfosuccinic acid (SSA) in the presence of dispersed SPEEK to obtain semi‐interpenetrating network blends. PVA–SSA/SPEEK blend membranes of different compositions were studied for their ion‐exchange capacity, proton conductivity, water uptake, and thermal and mechanical properties. The hydrated blend membranes show good proton conductivities in the range of 10^?3 to 10^?2 S/cm. When compared with pure component membranes, the PVA–SSA/SPEEK blend membranes also exhibit improvement in tensile strength, tensile modulus, and delay in the onset of thermal and chemical degradation. Semi‐interpenetrating nature of the blends is established from morphology and dynamic mechanical analysis. Morphology of the membranes was studied using scanning electron microscopy after selective chemical treatment. The dynamic mechanical properties of the membranes are examined to understand the miscibility characteristics of the blends. The relative proportions of PVA and SPEEK and the degree of crosslinking of PVA–SSA are important factors in determining the optimum properties for the blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of sulfonated polyetherimide/polyetherimide blend membranes

Polyetherimide (PEI) was sulfonated by chlorosulfonic acid (CSA) in 1,2‐dichloroethane for the first time. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, the ion‐exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increased accordingly. Water‐uptake testing and contact‐angle measurement showed that the hydrophilicity of the SPEI increases with the increase of the IEC. Membranes were fabricated from SPEI/PEI blends with different ratios. The morphologies of the blend membranes were examined by scanning electron microscopy, which showed that the membrane pore size is larger when SPEI with higher IEC was used. With the increase of SPEI ratio in the blend membranes, the membrane pore size also increased. The contact‐angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular backbone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1709–1715, 2004     

Solution‐blown SPEEK/POSS nanofiber–nafion hybrid composite membranes for direct methanol fuel cells

This study aims to develop novel hybrid composite membranes (NHMs) by impregnating Nafion solution into the porous sulfonated poly(ether ether ketone)/polyhedral oligomeric silsesquioxanes (SPEEK/POSS) nanofibers (NFs). The composite membrane was prepared by solution blowing of a mixture of SPEEK/POSS solution. The characteristics of the SPEEK/POSS NFs and the NHMs, including morphology, thermal stability, and performance of membrane as PEMs, were investigated. The performance of NHMs was compared with that of Nafion117 and SPEEK/Nafion composite membranes. Results showed that the introduction of POSS improved the proton conductivity, water swelling, and methanol permeability of membranes. A maximum proton conductivity of 0.163 S cm^?1 was obtained when the POSS content was 6 wt % at 80°C, which was higher than that of Nafion117 and SPEEK/Nafion. NHMs could be used as proton exchange membranes (PEMs) for fuel cell applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42843.     

聚醚砜/磺化聚醚醚酮共混膜的制备和性能

采用流延法制备了聚醚砜(PES)含量不同的PES/磺化聚醚醚酮(SPEEK)共混膜。PES与SPEEK具有良好的相容性。所制备PES/SPEEK共混膜的含水率、溶胀度和甲醇透过系数均随PES含量的增加而降低。虽然共混膜的质子传导性能有所降低.但阻醇性能和溶胀性能提高,这说明PES/SPEEK共混膜是一种很好的直接甲醇燃料电池用固体高分子电解质膜材料。