Aryl Ether Ketone Research Articles

Evaluation of particle coalescence and its implications in laser sintering

An experimental study on the melt and coalescence of different Poly(aryl ether ketones) (PAEK) powders was carried out. The study consisted of evaluating individual particles and neck growth using a hot stage platform. Three different methods of assessing particles dimensions were evaluated, and the coalescence was compared for the grades on three different substrates: glass, glass coated silicone and amorphous PEKK films, the last substrate with the intent to relate with the laser sintering process. It was found that all individual particles shrink prior to melting, achieving up to 30% reduction in perimeter at temperatures just above melting. This shrinkage is followed by an increase in size, mostly driven by viscous flow. Shrinkage is expected to affect neck growth by delaying coalescence, as particles are pulled away whilst neck increases. This is a plausible explanation for why neck growth occurs at a lower rate than predicted by most coalescence models. The use of different substrates does not seem to affect particle coalescence or change in dimension. Viscosity and particle size influence overall particle behaviour and melt, whilst morphology and porosity do not have a great impact in particles coalescence.

Sensitive and selective non-enzymatic glucose detection using electrospun porous CuO–CdO composite nanofibers

Porous CuO–CdO nanofibers with mean diameter of 463 nm and high surface-to-volume ratio were prepared by impregnating electrospun carboxylic-functionalized poly(arylene ether ketone) (PCA-PAEK) nanofibrous webs with metal acetate solution and subsequent calcination. The special morphology was demonstrated to be decided by ion exchange reaction between metal ions and functional groups on polymer. TGA and EDX analysis confirmed that Cd2+ was more readily to react with PCA-PAEK than Cu2+, and the amount of Cu2+ can be decreased by overloading of Cd2+, leading to the degradation of sensing performance. FT-IR proved the existence of the ion exchange reaction and demonstrated the products were highly pure CuO–CdO compounds with EDX and XRD spectra. The products detailedly investigated for direct electrocatalytic oxidation of glucose evaluated cyclic voltammetry and chronoamperometry. CuO–CdO nanofibers modified electrodes exhibited superiorities of good anti-interference, low detection limit and fast response of glucose, attributing to the enhanced conductivity brought by CdO, good electrocatalytic activity brought by CuO and large surface area brought by porous structure. The simple strategy of electrospinning porous nanofibers using PCA-PAEK as templates and combined CuO and CdO with good electrooxidation glucose functions opens a new route to generate novel conductive metal oxide hybrid nanofibers applied for glucose enzymeless sensors.

Enhanced proton conductivity and relative selectivity of sulfonated poly(arylene ether ketone sulfone) proton exchange membranes by using triazole-grafted 3-Glycidyloxypropyltrimethoxysilane

Herein, we demonstrate the fabrication of cross-linked membranes based on sulfonated poly(arylene ether ketone sulfone) containing pendant amino groups (AM-SPAEKS) and triazole-grafted 3-Glycidyloxypropyltrimethoxysilane (GT) cross-linkers by a sol-gel process, then the obtained cross-linked membranes are named as AMSP/GT membranes. The GT cross-linkers are synthesized by the ring-opening reaction of the epoxy group and 3-amino-1,2,4-triazole. The AMSP/GT cross-linked membranes exhibit excellent thermal, oxidation and dimensional stability. Furthermore, the AMSP/GT membranes possess a low methanol permeability coefficient (9.95 × 10−7 cm2 s−1 at 60 °C) due to the formation of cross-linked network structures. In addition, the proton conductivity and relative selectivity of the AMSP/GT membranes are higher, at elevated temperatures (>80 °C), than AM-SPAEKS membranes. The highest proton conductivity of 0.135 S cm−1 is demonstrated, for the AMSP/GT-30 membrane, at 100 °C. The relative selectivity of AMSP/GT-30 can reach 7.54 × 104 S scm−3 which is three times higher than that of the AM-SPAEKS, at 60 °C. These results indicate that the AMSP/GT membranes can be promising candidates for practical applications such as proton exchange fuel cells etc.

Alkaline anion exchange membrane from poly(arylene ether ketone)-g-polyimidazolium copolymer for enhanced hydroxide ion conductivity and thermal, mechanical, and hydrolytic stability

A series of alkaline anion exchange membranes (AAEMs) are synthesized from poly (arylene ether ketone) -poly (vinyl-1-butylimidazolium) graft copolymers (PAEK-g-[PBVIm-OH]) with different [PBVIm-OH] cationic chain lengths. The chemical structure of the synthesized polymers is confirmed by 1H NMR and FTIR analysis. Several essential properties of AAEMs such as water uptake, hydroxide ion conductivity, and thermal, mechanical and dimensional stability for fuel cell applications are investigated and correlated to the ion cluster dimension examined by small-angle x-ray scattering. The PAEK-g-[PBVIm-OH]-based AAEMs show excellent thermal, mechanical, and dimensional stability, as they have the thermal degradation temperature of 250 °C, the tensile strength of 7.7 MPa and the planar swelling ratio of 12% at 40 °C. The hydroxide ion conductivity increases with increasing PBVIm-OH graft chain length. The AAEM membrane with the longest PBVIm-OH chain length (MW of ∼7000 g mol−1) exhibits the highest hydroxide conductivity of 0.00878 S cm−1 at 40 °C and the highest elongation of 206.7% in the hydrate state. The membrane electrode assembly fabricated from this membrane shows the highest power density of 22 mW cm−2 at a current density of 55 mA cm−2, which is very promising for fuel cell applications.

Preparation and properties of anion exchange membranes based on multiple quaternary ammonium groups

Anion exchange membrane fuel cell (AEMFC) has attracting great attention as one of the most clean energy conversion technologies, because it has a facile electrochemical kinetics under alkaline condition and enables the use of non-precious metal catalysts. The reported anion exchange membranes were usually prepared by tethering quaternary ammonium groups (QA) to the backbone of chloromethylated or bromomethylated aromatic polymers by immersing in trimethylamine solution. However, they exhibit much low ionic conductivity and poor alkaline stability, which hinders the further development of AEMFC technology. In order to improve the ionic conductivity of anion exchange membranes, we located multi QA groups on one side chains for enhancing the local density of ionic groups. Therefore, we synthesized a type of small molecule with a quaternary ammonium group and an alkyl bromide. After gethering it onto 1,4-diazabicyclo[2.2.2] octane-functionalized poly(arylene ether ketone) by a quaternization reaction, tri-quaternized poly(arylene ether ketone) (TQPAEK) was successfully prepared with flexible side chains containing multi quaternary ammonium groups. Then a series of anion exchange membranes in OH- form were obtained by solution casting and then alkaline treatment. The ionic exchange capacity of these membranes in the range of 1.75–2.57 meq/g could be adjusted by controlling the degree of bromination of the precursor polymer. The water uptake, swelling ratio and hydroxide conductivity of TQPAEK membranes increased with the increasing IEC values. They also showed good thermal and mechanical stabilities. Especially, the introduction of flexible side chains significantly improved the elongation at the break of membranes, which reached up to 103.2%. Meanwhile, the tensile stress was still higher than 28 MPa. AFM images showed that the hydrophilic/hydrophobic phase-separation morphology was formed in these TQPAEK containing multi-quaternized flexible side chains. Therefore, TQPAEK exhibited high ionic conductivity of 74.35 mS/cm at 80°C. The results indicated that TQPAEK membranes had the potential to be used in alkaline AEMFCs.

Enhancement of fuel cell performance of sulfonated poly(arylene ether ketone) membrane using different crosslinkers

Fuel cells are considered as clean and efficient devices for the generation of electric power. The commercial viability of proton exchange membrane fuel cell largely depends on membrane properties. Thus, this paper emphasizes on the preparation of crosslinked sulfonated poly(arylene ether ketone) membranes and their evaluation for fuel cell application. Initially, the copolymer was synthesized using phenolphthalein monomer, potassium 2,5-dihydroxybenzenesulfonate and 4,4′-diflorobenzophenone. To improve the fuel cell performance, the copolymer was crosslinked with different mass% of polystyrene sulfonic acid-co-maleic acid sodium salt (PSSA-MA) and sulphothalic acid (SPTA). The physico-chemical properties of the resulting membranes were studied using various techniques. The microstructure of the membranes was examined by scanning electron microscopy and atomic force microscopy. The oxidative stability was performed in Fenton's solution at 80 °C and indicated that more than 92% of the membrane residue remained with a minimum loss of ion exchange capacity (IEC). The proton conductivity was investigated in fully hydrated state, which revealed that the proton conductivity of both the series of crosslinked membranes was increased with increasing the content of PSSA-MA and SPTA up to 20 mass%. Among the series, 20 mass% of PSSA-MA and SPTA incorporated crosslinked membranes exhibited the highest IEC values of 2.569 and 2.342 meq g−1, respectively. Similarly, the proton conductivity of PSSA-MA and SPTA crosslinked membrane was found to be 0.134 and 0.117 S cm−1 at 80 °C with 100% relative humidity. The performance of fuel cell study revealed that 20 mass% of PSSA-MA and SPTA crosslinked membranes demonstrated an excellent power density of 0.45 W cm−2 at 0.82 A cm−2 and 0.42 W cm−2 at 0.71 A cm−2, respectively. Thus, these two crosslinked membranes developed here could be used as promising candidates for fuel cell applications.

Preparation and characterization of ultralow dielectric and fibrous epoxy thermoset cured with poly(arylene ether ketone) containing phenolic hydroxyl groups

Poly(arylene ether ketone) containing naphthalene and phenolic hydroxyl groups (HPAEK) was prepared by polycondensation and demethylation reaction. Polymer cured epoxy resin with high-Tg was obtained through reactions between oxirane ring of epoxy and phenolic hydroxyl groups of HPAEK. Electrospinning technology was used to fabricate porous film. The porous film shows a high Tg value (262 °C), a low dielectric constant (1.9 at 1 MHz), and a low coefficient of thermal expansion (52 ppm °C−1). The thermal stability and water contact angle were also measured. The naphthalene and phenolic hydroxyl containing poly(arylene ether ketone) provides us with a new strategy to achieve ultralow dielectric constant materials via electrospinning.

Imidazolium-functionalized poly (arylene ether ketone) cross-linked anion exchange membranes

A series of phenolphthalein-based poly (arylene ether ketone) (PEK) copolymer are synthesized to prepare anion exchange membranes (AEMs). The ion group 1-vinyl imidazole is introduced on the unit of phenolphthalein-based as a hydrophilic segment and cross-linking agent. The structure of resulting membranes was investigated by 1H NMR and FT-IR. The well-defined microphase-separated structures were verified by TEM and SAXS profiles. The cross-linked membrane of ImPEK-0.4 exhibits high hydroxide conductivity (0.0836 S/cm, at 80 °C), excellent mechanical performance (69.6 MPa) and the maximum swelling ratio is only 7.95% at 80 °C. Furthermore, the excellent alkaline stability is demonstrated by immersing the prepared membrane in 1 M NaOH at 40 °C for 400 h. The ionic conductivity is still high to 0.0381 S/cm for ImPEK-0.4. These results indicate that combining phase separation architecture and crosslinking may possess potential applications for alkaline fuel cells (AFCs).

Poly(aryl ether ketone) based individual, binary and ternary nanocomposites for nuclear waste storage: mechanical, rheological and thermal analysis

In this study poly aryl ether ketone (PAEK) based nanocomposites containing multi walled carbon nanotubes, boron carbide and tungsten carbide nanofillers were irradiated with gamma rays of dosage 5000 kGy. These composites were prepared to estimate their potential in nuclear waste storage applications. The tensile properties, non destructive testing, rheological behavior and thermal properties of the composites were evaluated before and after gamma irradiation. The property variation after irradiation was influenced by the cross linking and chain scission of the polymer developed within the nanocomposites. In the tensile property analysis, the tensile modulus and the percentage elongation at break of all the nanocomposites were modified after gamma irradiation. Non destructive testing (NDT) showed all the samples were free from voids and cracks after gamma rays exposure. There was a slight decrease in the complex viscosity of the samples after irradiation indicating the predominance of the chain scission over cross linking. The decrease in melting temperature and the crystallization temperature of PAEK and the nanocomposites after irradiation suggested changes in the conformation of the polymer chains which was validated by the gel permeation chromatography (GPC) analysis. Even though the properties of the virgin PAEK were significantly reduced after gamma irradiation, the percentage reduction in the properties of polymer nanocomposites was not considerable especially with the ones reinforced with tungsten carbide.

Naphthalene‐containing poly(arylene ether ketone) with low dielectric constant

ABSTRACTA low dielectric constant poly(arylene ether ketone) containing naphthalene and trifluoromethyl groups (FPNAEK) were prepared and characterized. The FPNAEK showed excellent thermal stability (Td5 = 443 °C ) and low water absorption. The dielectric constant decreased significantly after introducing trifluoromethyl group, in comparision with poly(arylene ether ketone) containing naphthalene (PNAEK). The dielectric constant of FPNAEK is about 2.5 between 1 kHz and 1 MHz at room temperature, which is much lower than that of commercial poly(ether ether ketone) (3.3) and PNAEK (2.78). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46857.

Tungsten carbide, boron carbide, and MWCNT reinforced poly(aryl ether ketone) nanocomposites: Morphology and thermomechanical behavior

ABSTRACTThis study involves the development and thermo‐mechanical characterization of the individual, binary, and ternary nanocomposites using radiation resistant fillers like boron carbide (B4C), tungsten carbide (WC), and functionalized multi‐walled carbon nanotubes (F‐MWCNT) in a high performance polymer, namely, poly aryl ether ketone (PAEK). Transmission electron microscopy studies revealed the distribution and dispersion of nanofillers in the matrix. It has been observed that the presence of WC and F‐MWCNT in PAEK matrix significantly enhanced the tensile strength of the composite whereas B4C made it stiff and brittle in nature. The tensile property improvement caused by WC and F‐MWCNT has been correlated with the tensile fracture surface morphology studies. Dynamic mechanical analysis provided insight into the positive effect of nanofillers in delaying the relaxation of polymer chains. The thermogravimetric analysis gave indications on the increase in the thermal stability of the nanocomposites with the increase of nanofillers content. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47032.

UV‐curable sol–gel based protective hybrid coatings

UV‐curable, novel, fluorinated polyether ether ketone urethane acrylate oligomer (FPEEKUA) has been synthesized and used as corrosion‐protector in sol–gel hybrid coatings for metallic substrates. Incorporation of FPEEKUA and sol–gel in the formulations improved coatings’ physical properties such as gel content, hardness, adhesion, gloss, flexibility, and contact angle. Due to strong interaction between acrylate and highly crosslinked structures, mechanical properties improved drastically with homogenously dispersed structures throughout the organic matrix, while water uptake values decreased and thermal stability and char yields increased. Highest contact angle values were measured up to 94° with shinny coatings. The results are important for two reasons. First, polyether ether ketone (PEEK) immiscibility problem are overcome by using reactive oligomer and benefitted from high performance properties of poly(arylene ether ketones) (PAEK)s in hybride coating applications. Second, Coatings combine the advantages of sol–gel with poly(arylene ether ketone urethane acrylate) (PAEKUA) oligomer and they can be used as barrier coatings in metal corrosion protection. Performance tests in corrosive mediums at room temperature of chlorine solution (bleach) for 24 h and also in a 10 wt% HCl solution for 92 h produced promising results for use in corrosion mitigation applications in highly corrosive downstream oil and gas industry. POLYM. ENG. SCI., 59:E146–E154, 2019. © 2018 Society of Plastics Engineers

Syntheses of carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures through the self-condensations of aromatic dicarboxylic anhydrides

Carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures were synthesized by the self-condensations of aromatic dicarboxylic anhydrides. A linear poly(arylene ether ketone) was obtained from an AB monomer, 4-phenoxyphthalic anhydride, whereas a hyperbranched poly(arylene ether ketone) was obtained using an AB2 monomer, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride. The method for the synthesis of the hyperbranched poly(arylene ether ketone) is notable, because it provides a high ion-exchange capacity, above 7 mmol g−1, through a one-pot polycondensation. These functional polymers are soluble in several organic solvents and aqueous NaOH, in contrast to typical poly(ether ketone)s, while they retain the high thermal stabilities of their backbones. Carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures were synthesized by the self-condensations of aromatic dicarboxylic anhydrides. A linear poly(arylene ether ketone) was obtained from an AB monomer, 4-phenoxyphthalic anhydride, while a hyperbranched poly(arylene ether ketone) was obtained using an AB2 monomer, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride. The method for the synthesis of the hyperbranched poly(arylene ether ketone) is notable because it provides a high ion-exchange capacity, above 7 mmol g−1, through a one-pot polycondensation.

High performance membranes based on new 2-adamantane containing poly(aryl ether ketone) for vanadium redox flow battery applications

Membranes are essential separator components in the vanadium redox flow battery (VRFB). Many low cost and high performance membranes have been developed for this purpose, but, the chemical stability of these membranes remains a considerable challenge. Consequently, there is a pressing need to develop advanced membranes for the vanadium redox flow battery with improved performance and stability. In this reported work, the next generation of adamantane containing poly(ether ketone)s membranes that have better performance, lower cost and are more environmentally friendly were prepared and used in vanadium redox flow battery. The subject quaternized 2-adamantane containing poly(ether ketone) membranes exhibited significantly higher performance in the redox battery than a Nafion117 membrane and a N212 membrane (coulombic efficiency 98.3% vs. 96.5% (Nafion117) and 91.4% (N212)); voltage efficiency 81.9% vs. 76.7% (Nafion117) and 81.6% (N212); energy efficiency 80.5% vs. 74.0% (Nafion117) and 74.6% (N212), at 140 mA cm−2). Moreover, the resulting membranes exhibited high stability during in-situ battery cycling test and in an ex-situ chemical oxidation stability test.

HT-PEMs based on nitrogen-heterocycle decorated poly (arylene ether ketone) with enhanced proton conductivity and excellent stability

The proton transport can be enhanced by properly controlling the chemical structure of side chains. In this work, polyelectrolytes supported on poly (arylene ether ketone), decorated with four kinds of nitrogen-heterocycles, were prepared as alternative materials for high-temperature proton exchange membrane (HT-PEM) applications. Particularly, the “prominent basic” alongside backbone makes positive imidazole group more effective than other three to promote phosphoric acid doping, enhance proton conductivity and avoid phosphoric acid leakage. The obtained BrPAEK-MeIm1.6 membranes (1.6 imidazole/unit), with PA doping level of 19.2 in 1 h acid absorption process, exhibited the conductivity of 0.091 S cm−1 at 170 °C. Under harsh experimental conditions, membrane with higher imidazole exhibited relatively higher phosphoric acid retention ability (27% enhancement). The stability of proton conductivity has also been demonstrated, which indicates that the PA/BrPAEK-MeIm1.6 come to an equilibrium state with 77.7% of initial conductivity after 5 h. Then, there is almost negligible conductivity loss within 30 h. These results provide a basic understanding of nitrogen-heterocyclic addition and PA absorption and open up avenues for further research in this area.

Preparation and properties of novel alternating poly(aryl ether ketone)

Novel alternating poly(aryl ether ketone)s (PAEKs) were prepared from a multiple aromatic difluoroketone monomer, that is, containing six aromatic rings via nucleophilic substitution polycondensation with various bisphenols. Each chain segment of the synthesized poly aryl ether ketone alternating copolymer was regularly separated by bisphenol units, which resulted in improvements in their thermal stability and solubility in common organic solvents. All glass transition temperatures of the alternating PAEKs were above 179°C, and the temperatures at 5% weight loss were above 446°C under nitrogen atmosphere. Wide-angle X-ray diffraction patterns confirmed that the resulting PAEKs were amorphous. PAEKs can form strong, transparent, and flexible films by solution casting, with a tensile strength of 72–79 MPa, Young’s modulus of 1.5–2.0 GPa, and elongation at break of 7–17%.

Enhanced Performance of a Sulfonated Poly(arylene ether ketone) Block Copolymer Bearing Pendant Sulfonic Acid Groups for Polymer Electrolyte Membrane Fuel Cells Operating at 80% Relative Humidity.

The series of sulfonated poly(arylene ether ketone) (SPAEK) block copolymers with controlled F-oligomer length bearing pendant diphenyl unit were synthesized via a polycondensation reaction. Sulfonation was verified by 1H NMR analysis to introduce sulfonic acid group selectively and intensively on the pendant diphenyl unit of polymer backbones. The SPAEK membranes fabricated by the solution casting approach were very transparent and flexible with the thickness of ∼50 μm. These membranes with different F-oligomer lengths were investigated to the physiochemical properties such as water absorption, dimensional stability, ion exchange capacity, and proton conductivity. As a result, the SPAEK membranes (X4.8Y8.8, X7.5Y8.8, and X9.1Y8.8) in accordance to increasing the length of hydrophilic oligomer showed excellent proton conductivity in range of 131-154 mS cm-1 compared to Nafion-115 (131 mS cm-1) at 90 °C under 100% relative humidity (RH). Among the SPAEK membranes, proton conductivity of SPAEK X9.1Y8.8 (140.7 mS cm-1) is higher than that of Nafion-115 (102 mS cm-1) at 90 °C under 80% RH. The atomic force microscopy image demonstrated that number of ion transport channels is increased with increase in the length of hydrophilic oligomer in the main chains, and the morphology is proved to be related to the proton conductivity. The synthesized SPAEK membrane exhibited a maximum power density of 324 mW cm-2, which is higher than that of Nafion-115 (291 mW cm-2) at 60 °C under 100% RH.

Crosslinking effect in nanocrystalline cellulose reinforced sulfonated poly(aryl ether ketone) proton exchange membranes

Two novel series of poly(aryl ether ketone)s (PAEK) bearing pendant carboxylic acid groups have been synthesized, and subsequently sulfonated to obtain sulfonated poly(aryl ether ketone)s with carboxylic acid groups (SPAEK-COOH-x). The expected structures of the sulfonated copolymers were confirmed by FTIR. Modified nanocrystalline cellulose (NCC) was prepared and introduced into the SPAEK-COOH-x as the “performance-enhancing” filler and crosslinking agent. The nanocomposite proton exchange membranes were prepared via a solution-casting procedure. The composite membranes containing NCC presented the higher proton conductivity and better mechanical properties. After further crosslinking, the covalent crosslinked composite membranes showed even better mechanical properties while the proton conductivity and thermal stability were maintained. The hydrophilic/hydrophobic domains were observed from the TEM morphology investigation of COOH-10/NCC-y and C/COOH-10/NCC-y membranes. A balance of mechanical stabilities, proton conductivity, and thermal property could be designed by the incorporation of NCC and the crosslinking between NCC and SPAEK-COOH-10 to meet the requirements for the applications in the fuel cells.

Effect of the degree of branching of hyperbranched poly(aryl ether ketone) template on the properties of self-assembled CdS nanocrystals

In this work we have investigated the effect of the degree of branching of hyperbranched poly(aryl ether ketone) (expressed as HPAEK) on the fluorescence spectra of the CdS/poly(aryl ether ketone) nanocomposites. CdS/HPAEK nanocomposites have been prepared by in situ synthesis method where hyperbranched poly(aryl ether ketone) with different branch degree as the ligand. The structure identifications of HPAEK and CdS/HPAEK nanocomposites were carried out by fourier transform infrared spectrometer (FT-IR) and nuclear magnetic resonance (NMR). The particle size and distribution of CdS in HPAEK matrix were determined by high resolution transmission electron microscopy (HRTEM). The thermal properties of HPAEK and CdS/HPAEK nanocomposites have been evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Optical properties of CdS/HPAEK nanocomposites have been discussed in terms of HPAEK polymer matrix with different branch degree, which were carried out by UV–Vis absorption and photoluminescence spectroscopy.

Poly(ether ether ketone) grafted with sulfoalkylamine as proton exchange membrane

A series of side-chain-type sulfonated poly(arylene ether ketone)s with high ion exchange capacity (IEC) values were prepared by polycondensation reaction of 4,4′-difluorobenzophenone with 2,2′-bis(3-amino-4-hydroxyphenyl) and bisphenol A, followed by post-grafting reaction using 1,4-butanesultone. For these obtained membranes, sulfoalkylamine functionalized poly(ether ether ketone) (SAm-PEEK)-0.8 with the highest IEC of 3.42 mequiv. g−1 displayed the highest proton conductivity of 0.11 S cm−1 at 25°C and 0.167 S cm−1 at 60°C, respectively. The morphology of these membranes was investigated by transmission electron microscope analysis. The result showed that these membranes exhibited well-connected hydrophilic channels due to their high IEC values and densely populated flexible acid side chains. Owing to their low methanol permeability and high selectivity, SAm-PEEK- x membranes are promising candidates for direct methanol fuel cell applications.