Mixed matrix membranes of sodium alginate and poly(vinyl alcohol) for pervaporation dehydration of isopropanol at different temperatures

Mixed matrix membranes of sodium alginate (NaAlg) and poly(vinyl alcohol) (PVA) containing 5 and 10 wt.% silicalite-1 particles were fabricated by solution casting method and the cured membranes were crosslinked with glutaraldehyde. These membranes were used in pervaporation (PV) dehydration of isopropanol at 30, 40, 50 and 60 °C. Membrane morphology was studied by scanning electron microscopy and universal testing machine to assess their mechanical strengths. Swelling results of the pristine and mixed matrix membranes were correlated with their PV performances. Selectivities of the mixed matrix membranes of NaAlg were 11,241 and 17,991 with the fluxes of 0.039 and 0.027 kg/m² h, respectively, for 5 and 10 wt.% silicalite-1 loadings. Corresponding values for mixed matrix membranes of PVA were 1295 and 2241, and 0.084 and 0.069 kg/m² h, respectively, for 10 wt.% water-containing feed at 30 °C. Pristine membranes of NaAlg and PVA exhibited lower selectivities of 653 and 77 with increased fluxes of 0.067 and 0.095 kg/m² h, respectively. From the temperature dependence of flux and diffusivity data with 10 wt.% water-containing feed, Arrhenius plots were constructed to compute heat of sorption, ΔH_s values. Mixed matrix membranes of NaAlg were better than PVA mixed matrix membranes at all compositions (10-40 wt.%) of water. Molecular dynamics (MD) simulation was employed to compute the interfacial interaction energies of NaAlg and PVA polymers with silicalite-1 filler; also sorption of liquid molecules was computed. Simulated diffusivities compared well with the experimental data. Thermodynamic treatment of sorption, diffusion and permeation processes was attempted based on the Flory-Huggins theory to explain the PV performances of the membranes.     

Impedance spectroscopic investigation of the interactions between phosphatidylethanolamine and α-tocopherol in bilayer membranes

Electric capacity and electric conductance of lipid membranes composed of phosphatidylethanolamine and α-tocopherol were determined by electrochemical impedance spectroscopy. These components were chosen for the study because they are present in biological membranes and they fulfill essential functions in lively organisms. A domain structures appear as a result of phosphatidylethanolamine-α-tocopherol membrane formation. Formation of the domains can explain the deviation from the additivity rule. This equilibrium was described by mathematical equations and was further verified experimentally. Based on the derived equations, the surface area of domain was calculated; it amounts to 320 Å². This value is consistent, taking into consideration ordering and condensation effects of α-tocopherol on the phosphatidylethanolamine, with a stoichiometry of such a domain equal to 4:1.     

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.     

New highly proton-conducting membrane poly(vinylpyrrolidone)(PVP) modified poly(vinyl alcohol)/2-acrylamido-2-methyl-1-propanesulfonic acid (PVA-PAMPS) for low temperature direct methanol fuel cells (DMFCs)

A new type of chemically cross-linked polymer blend membranes consisting of poly(vinyl alcohol) (PVA), 2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) and poly(vinylpyrrolidone) (PVP) have been prepared and evaluated as proton conducting polymer electrolytes. The proton conductivity (σ) of the membranes was investigated as a function of cross-linking time, blending composition, water content and ion exchange capacity (IEC). Membranes were also characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), and the differential scanning calorimetry (DSC). Membrane swelling decreased with cross-linking time, accompanied by an improvement in mechanical properties and a small decrease in proton conductivity due to the reduced water absorption. The membranes attained 0.088 S cm⁻¹ of the proton conductivity and 1.63 mequiv g⁻¹ of IEC at 25±2 °C for a polymer composition PVA-PAMPS-PVP being 1:1:0.5 in mass, and a methanol permeability of 6.1×10⁻⁷ cm² s⁻¹, which showed a comparable proton conductivity to Nafion 117, but only one third of Nafion 117 methanol permeability under the same measuring conditions. The membranes displayed a relatively high oxidative durability without weight loss of the membranes (e.g. 100 h in 3% H₂O₂ solution and 20 h in 10% H₂O₂ solution at 60 °C). PVP, as a modifier, was found to play a crucial role in improving the above membrane performances.     

Dispersions of carbon nanotubes in sulfonated poly[bis(benzimidazobenzisoquinolinones)] and their proton-conducting composite membranes

A sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI) possessing a conjugated pyridinone ring was shown to be effective for dispersing multiwalled carbon nanotubes (MWCNTs) in DMSO. The dispersions in which the SPBIBI to MWCNTs mass ratio was 4:1 demonstrated the highest MWCNTs concentrations, i.e., 1.5-2.0 mg mL⁻¹, and were found to be stable for more than six months at room temperature. Through casting of these dispersions, MWCNTs/SPBIBI composite membranes were successfully fabricated on substrates as proton exchange membranes for fuel cell applications and showed no signs of macroscopic aggregation. The properties of composite membranes were investigated, and it was found that the homogeneous dispersion of the MWCNTs in the SPBIBI matrix altered the morphology structures of the composite membranes, which lead to the formation of more regular and smaller cluster-like ion domains. As a result, and in comparison to a pristine SPBIBI membrane, the composite membranes displayed more significant proton conductivities, especially at low relative humidity, without sacrificing other excellent properties, such as thermal, dimensional and oxidative stabilities. For instance, the composite membranes with an MWCNTs content only of 0.5 wt% exhibited proton conductivities of 0.021 S cm⁻¹ at 50 RH% and 70 °C, a value almost fourfold as high as that of the pristine SPBIBI membranes under identical conditions (0.005 S cm⁻¹). The result was comparable to Nafion 117 (0.021 S cm⁻¹). The homogenous dispersion of the MWCNTs and the efficient enhancement the SPBIBI performance were attributed to the π-π interaction between the pyridinone ring and the sidewalls of the MWCNTs which changed the morphological structure of composite membranes as revealed by TEM. A combination of a low methanol crossover with excellent thermo-oxidative and water stabilities indicated that the SPBIBI composite membranes were good candidate materials for proton exchange membranes in fuel cell applications.     

Inorganic-organic hybrid membranes with anhydrous proton conduction prepared from tetramethoxysilane/methyl-trimethoxysilane/trimethylphosphate and 1-ethyl-3-methylimidazolium-bis (trifluoromethanesulfonyl) imide for H2/O2 fuel cells

Anhydrous proton-conducting inorganic-organic hybrid membranes were prepared by sol-gel process with tetramethoxysilane/methyl-trimethoxysilane/trimethylphosphate and 1-ethyl-3-methylimidazolium-bis (trifluoromethanesulfonyl) imide [EMI][TFSI] ionic liquid as precursors. These hybrid membranes were studied with respect to their structural, thermal, proton conductivity, and hydrogen permeability properties. The Fourier transform infrared spectroscopy (FT-IR) and ³¹P, ¹H, and ¹³C nuclear magnetic resonance (NMR) measurements have shown good chemical stability, and complexation of PO(OCH₃)₃ with [EMI][TFSI] ionic liquid in the studied hybrid membranes. Thermal analysis including TG and DTA confirmed that the membranes were thermally stable up to 330 °C. Thermal stability of the hybrid membranes was significantly enhanced by the presence of inorganic SiO₂ framework and high stability of [TFSI] anion. The effect of [EMI][TFSI] ionic liquid addition on the microstructure of the membranes was studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) micrographs and no phase separation at the surfaces of the prepared membranes was observed and also homogeneous distribution of all elements was confirmed. Proton conductivity of all the prepared membranes was measured from −20 °C to 150 °C, and high conductivity of 5.4 × 10⁻³ S/cm was obtained for 40 wt% [EMI][TFSI] doped 40TMOS-50MTMOS-10PO(OCH₃)₃ (mol%) hybrid membrane, at 150 °C under anhydrous conditions. The hydrogen permeability was found to decrease from 1.61 × 10⁻¹¹ to 1.39 × 10⁻¹² mol/cm s Pa for 40 wt% [EMI][TFSI] doped hybrid membrane as the temperature increases from 20 °C to 150 °C. For 40 wt% [EMI][TFSI] doped hybrid membrane, membrane electrode assemblies were prepared and a maximum power density value of 0.22 mW/cm² at 0.47 mA/cm² as well as a current density of 0.76 mA/cm² were obtained at 150 °C under non-humidified conditions when utilized in a H₂/O₂ fuel cell.     

Electrospun hydrophilic fumed silica/polyacrylonitrile nanofiber-based composite electrolyte membranes

Hydrophilic fumed silica (SiO₂)/polyacrylonitrile (PAN) composite electrolyte membranes were prepared by electrospinning composite solutions of SiO₂ and PAN in N,N-dimethylformamide (DMF). Among electrospinning solutions with various SiO₂ contents, the 12 wt% SiO₂ in PAN solution has highest zeta potential (−40.82 mV), and exhibits the best dispersibility of SiO₂ particles. The resultant 12 wt% SiO₂/PAN nanofiber membrane has the smallest average fiber diameter, highest porosity, and largest specific surface area. In addition, this membrane has a three-dimensional network structure, which is fully interconnected with combined mesopores and macropores because of a good SiO₂ dispersion. Composite electrolyte membranes were prepared by soaking these porous nanofiber membranes in 1 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol%). It is found that 12 wt% SiO₂/PAN electrolyte membrane has the highest conductivity (1.1 × 10⁻² S cm⁻¹) due to the large liquid electrolyte uptake (about 490%). In addition, the electrochemical performance of composite electrolyte membranes is also improved after the introduction of SiO₂. For initial cycle, 12 wt% SiO₂/PAN composite electrolyte membrane delivers the discharge capacity of 139 mAh g⁻¹ as 98% of theoretical value, and still retains a high value of 127 mAh g⁻¹ as 89% at 150th cycle, which is significantly higher that of pure PAN nanofiber-based electrolyte membranes.     

Effects of crosslinkers on semi-interpenetrating polymer networks of Nafion and fluorine-containing polyimide

A series of reinforced composite membranes were prepared from Nafion^®212 and crosslinkable fluorine-containing polyimide (FPI) with various crosslinkers. The crosslinkable FPI reacts with the crosslinkers and forms semi-interpenetrating polymer networks (semi-IPN) structure with Nafion^®212. The water uptake, swelling ratio, mechanical properties, thermal behavior, proton conductivity, and chemical oxidation stability of the composite membranes are studied. The degree of crosslinking is characterized by gel fraction of the composite membranes. Compared to pure Nafion^®212, the composite membranes exhibit excellent thermal stability, improved mechanical properties and dimensional stability. The tensile strength of the composite membranes is in the range of 37.3-51.2 MPa. All the composite membranes exhibit high proton conductivity which ranges from 1.9 × 10⁻² to 9.9 × 10⁻² S cm⁻¹. The proton conductivity of the composite membrane with 2-propene-1-sulfonic acid sodium salt (SAS) as the crosslinker is 9.9 × 10⁻² S cm⁻¹ at 100 °C which is similar to that of Nafion^®212 under the same condition.     

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.     

Ionic conductivity of chitosan membranes

Chitosan membranes with various degrees of deacetylation and different molecular weights (MW) were prepared by film casting with aqueous solutions of chitosan and acetic acid. Ultraviolet (UV) spectrometry and infrared (IR) spectrometry were used to determine the degree of deacetylation (DDA) of chitosan. The viscosity-average MW of chitosan was measured in an aqueous solvent system of 0.25 M CH₃COOH/0.25 M CH₃COONa. The intrinsic ionic conductivities of the hydrated chitosan membranes were investigated using impedance spectroscopy. It was found that the intrinsic ionic conductivity was as high as 10⁻⁴ S cm⁻¹ after hydration for 1 h. The tensile strength and breaking elongation of the membranes were evaluated according to standard ASTM methods. The crystallinity and swelling ratio of the membranes were examined. A tentative mechanism for the ionic conductivity of chitosan membranes is also suggested.     

Nafion/Analcime and Nafion/Faujasite composite membranes for polymer electrolyte membrane fuel cells

The Nafion/zeolite composite membranes were synthesized for polymer electrolyte fuel cells (PEMFCs) by adding zeolite in the matrix of Nafion polymer. Two kinds of zeolites, Analcime and Faujasite, having different Si/Al ratio were used. The physico-chemical properties of the composite membranes such as water uptake, ion-exchange capacity, hydrogen permeability, and proton conductivity were determined. The fabricated composite membranes showed the significant improvement of all tested properties compared to that of pure Nafion membrane. The maximum proton conductivity of 0.4373 S cm⁻¹ was obtained from Nafion/Analcime (15%) at 80 °C which was 6.8 times of pure Nafion (0.0642 S cm⁻¹ at 80 °C). Conclusively, Analcime exhibited higher improvement than Faujasite.     

Impedance analysis of phosphatidylcholine-cholesterol system in bilayer lipid membranes

Electrochemical impedance spectroscopy was used for the study of two-component lipid membranes. Phosphatidylcholine (lecithin, PC) and cholesterol (Ch) were chosen for the study because they are present in biological membranes and they fulfil essential functions in lively organisms. The theory of equilibrium between components of the membranes has been developed in order to obtain the parameters describing the PCCh complex. The equilibrium between the PC, Ch and PCCh complex on the basis of derived equations was considered and forming the 1:1 complex was proved. The following parameters of the complex were determined: capacitance (C₃), conductance , area occupied by complex molecule (A₃) as well as stability constant of the complex (K).     

Preparation, characterization, and properties of new crosslinked proton-conducting membranes with polyoxyalkylene moieties

A new class of crosslinked proton-conducting membranes (CPMs) with polyoxyalkylene moieties was designed and prepared based on poly(styrene-co-maleic anhydride) modified with 2-aminoethanesulfonic acid sodium salt (AESA-Na) and polyoxyalkylenediamines (PEGDAs). The number density of the pendant of sulfonate group was controlled by the ratio of AESA-Na to PEGDA. The resulted membranes possess good mechanical strength and excellent flexibility. The structural characterizations of these membranes were confirmed by FT-IR and solid-state ¹³C NMR spectra. All these membranes exhibit a wholly amorphous morphology, and show a one-step weight loss from 350 °C, indicating their good thermal stability. The CPM sample with 1.25 mequiv SO₃H per gram reaches the proton conductivity of 0.21 S cm⁻¹ at 30 °C and 0.49 S cm⁻¹ at 95 °C, respectively. Moreover, these protonated membranes show adequate oxidative stability in Fenton's reagent at 30 °C.     

Synthesis of organosiloxane-based inorganic/organic hybrid membranes with chemically bound phosphonic acid for proton-conductors

Proton conductive inorganic-organic hybrid membranes were synthesized from 3-glycidoxypropyltrimethoxysilane (GPTMS) and phosphonoacetic acid (PA) with various ratios by a sol-gel process. Self-standing, homogeneous, highly transparent membranes were synthesized. TG-DTA analyses indicated that these membranes were thermally stable up to 200 °C. The results of FT-IR and ¹³C NMR revealed that phosphonic acid groups of PA were chemically bound to organosiloxane network as a result of reaction between PA and GPTMS. The leach out of phosphonic acid groups from GPTMS-PA to water was reduced compared with phosphoric acid groups from GPTMS-H₃PO_4. The proton conductivity of the hybrid membranes increased with phosphonic acid content. The conductivity of GPTMS/PA with a 1/1.05 ratio at 130 °C was 8.7 × 10⁻² S cm⁻¹ at 100% relative humidity (RH).     

Nanocrystalline cellulose reinforced PVDF-HFP membranes for membrane distillation application

Polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) membranes containing different amounts of nanocrystalline cellulose (NCC) were fabricated by electrospining technique for application in membrane distillation (MD). The effect of incorporating NCC on the mechanical strength, morphology, pore size distribution, and liquid entry pressure (water) of the fibrous was investigated. Incorporation of NCC in PVDF-HFP matrix improved the tensile strength and Young's modulus and narrowed down the pore size distribution of the fabricated membranes. Liquid entry pressure, which is an important parameter to ensure high salt rejection of the membranes in MD, was improved from ~ 19 psi to ~ 27 psi with the addition of 2 wt.% NCC. Fabricated membranes were tested in direct contact membrane distillation (DCMD). MD operation data revealed water flux of 10.2–11.5 Lh^− 1 m^− 2 with salt rejection of 99% for these NCC-incorporated membranes.     

Modification of macroporous stainless steel supports with silica nanoparticles for size selective carbon membranes with improved flux

Silica nanoparticles were slip cast into porous stainless steel supports, which were then coated with polyfurfuryl alcohol and pyrolyzed to make nanoporous carbon membranes. The single gas permeances of the membranes formed on modified stainless steel supports were found to be between two and three orders of magnitude larger than the permeances of nanoporous carbon membranes (<10⁻¹¹ mol m⁻² s⁻¹ Pa⁻¹) synthesized on unmodified supports. Importantly, these high permeances (10⁻⁸-10⁻⁹ mol m⁻² s⁻¹ Pa⁻¹) were achieved within the same range of O₂/N₂ selectivities (3-5) that we have observed for single gases permeating at much lower fluxes through the nanoporous carbon membranes on unmodified supports. The nanoporous carbon membranes also were formed by combining the silica nanoparticles with polyfurfuryl alcohol resin and applying the mixture directly onto an unmodified support. This simpler process was as effective in producing selective-high permeance membranes. In both cases the significant increase in permeance without loss of selectivity is attributed to the silica nanoparticles filling the macropores of the stainless steel supports, thereby leading to the formation of very thin but selective carbon layers.     

Electrodeposition of Ag and Pd on a reconstructed Au(1 1 1) electrode surface studied by in situ scanning tunneling microscopy

Electrochemical deposition of Ag and potential-induced structural change of the deposited Ag layer on a reconstructed surface of Au(1 1 1) electrode were followed by in situ scanning tunneling microscope (STM). A uniform Ag monolayer was formed on a reconstructed Au(1 1 1) surface in a 50-mM H₂SO₄ solution at +0.3 V (vs. Ag/AgCl) after adding a solution containing Ag₂SO₄ so that the concentration of Ag⁺ in the STM cell became ca. 2 μM. No characteristic height corrugation such as the Au reconstruction was observed on the surface, indicating that the lifting of the substrate Au reconstruction occurred by Ag deposition. The formed Ag monolayer was converted to a net-like shaped Ag nano-pattern of biatomic height when the potential was stepped from +0.3 to −0.2 V in the solution containing 2 μM Ag⁺. This result indicates that the substrate Au(1 1 1)-(1 × 1) surface was converted to the reconstructed surface even in the presence of Ag adlayer. Quite different structure was observed for Pd deposition on a reconstructed surface of Au(1 1 1) electrode at +0.3 V and the origin for this difference between Ag and Pd deposition is discussed.     

Membrane-assisted production of S1P loaded SLNs for the treatment of acne vulgaris

The incorporation of the sparingly soluble drug sphingosine-1-phosphate (S1P) into solid lipid nanoparticle (SLN) formulations using a ceramic membrane-assisted emulsification technique was investigated. SLNs have been used as an alternative to emulsions and liposomes in cosmetic and pharmaceutical preparations for the last two decades. They were prepared by replacing the liquid lipid part of the emulsions with a lipid part, which is solid at room temperature and/or at body temperature. The influence of a number of parameters on the particle size and size distribution of formulation and on the lipid flux were issued here. The chosen experiment parameters were: Lipid concentration varied from 5 to 20% w/w at various trans-membrane pressures (4-6 bar) and at aqueous phase cross-flow velocities varied from 2 to 12.5 m/s. A mono-channel ceramic membrane with a pore size of 0.2 µm and a 0.4 µm 19-channel membrane were used. It was shown that the investigated membrane system allows the preparation of SLNs with a mean particle size between 0.2 and 1 µm. The advantages of using a membrane-supported process are excellent scaling-up abilities and the control of the particle size through an appropriate selection of process parameters such as aqueous phase cross-flow velocity, lipid phase pressure and membrane properties.     

Polyvinylidene fluoride and polyetherimide hollow fiber membranes for CO2 stripping in membrane contactor

Porous polyvinylidene fluoride (PVDF) and polyetherimide (PEI) hollow fiber membranes incorporating polyethylene glycol (PEG) were prepared via spinning process for CO₂ membrane stripping. CO₂ loaded diethanolamine solution was used as liquid absorbent while N₂ was used as a strip gas. The characterization study of the fibers was carried out in terms of permeation test, contact angle measurement and liquid entry pressure (wetting pressure). Performance study via membrane contactor stripping was carried out at specific operating condition. The experimental results showed that PVDF membrane have high gas permeation, effective surface porosity and contact angle despite having lower liquid entry pressure in comparison with PEI membrane. PVDF-PEG membrane showed the highest stripping flux of 4.0 × 10⁻² mol m⁻² s⁻¹ at 0.7 ms⁻¹ compared to that of PEI membrane. Although the stripping flux for PEI-PEG membranes was slightly lower than PVDF membrane (e.g. 3.5 × 10⁻² mol m⁻² s⁻¹ at liquid velocity of 0.85 ms⁻¹), the membrane wetting pressure of PEI membrane is higher than hydrophobic PVDF membrane. Long term performance of both membranes showed severe flux reduction but started to level-off after 30 h of operation.     

Sulfonated poly(ether ether ketone) membranes crosslinked with sulfonic acid containing benzoxazine monomer as proton exchange membranes

The incorporation of benzoxazine (Ba) or sulfonic acid containing benzoxazine (SBa) as a crosslinking agent in SPEEK proton exchange membrane (PEM) can substantially improve the SPEEK membrane performance. The SPEEK-SBa membranes give higher effective selectivity than corresponding SPEEK-Ba membranes under close crosslinker loading and thus are more suitable to be used in direct methanol fuel cells. The best achieved SPEEK-SBa composition (SBa40) gives reasonable proton conductivity (0.91 × 10⁻² S cm⁻¹) but significantly lower methanol permeability (6.5 × 10⁻⁸ S² cm⁻¹). The achieved effective selectivity (Φ = SPEEK-SBa40: 14.0 × 10⁴ S s cm⁻³) is substantially higher than the plain SPEEK (Φ = 7.24 × 10⁴ S s cm⁻³) which has great potential for practical applications in DMFCs.