基于聚苯并咪唑/超支化聚合物的交联共混体系的高温质子交换膜

在可溶性高分子量芳醚型聚苯并咪唑(OPBI)基体中引入超支化聚对氯甲基苯乙烯(H-VBC), 通过 便捷的溶液共混-浇铸法, 制备了基于聚苯并咪唑/超支化聚合物的新型交联体系(OPBI/H-VBC-1和OPBI/ H-VBC-2), 并对膜进行季铵盐化处理(OPBI/H-VBC-QA-1和OPBI/H-VBC-QA-2), 实现了复合膜综合性能的提升. 与原始OPBI膜相比, 交联型复合膜表现出优异的尺寸稳定性和“抗塑化”能力. 在85%磷酸中浸泡72 h后, OPBI/H-VBC-2和OPBI/H-VBC-QA-2的体积膨胀率只有184.2%和152.4%, 而OPBI的体积膨胀率达到336.5%; OPBI/H-VBC-2和OPBI/H-VBC-QA-2的最大拉伸强度分别达到36.3和21.9 MPa, 比单一OPBI膜的10.9 MPa提高了56%~233%. 研究发现, 季铵盐化的复合膜具有更高的质子传导率（在200 ℃下的质子传导率分别达到151.5和103.4 mS/cm）与磷酸吸收水平比值. 对比研究发现, 所制备的交联型复合膜比已报道大多数高温质子交换膜(HT-PEM)具有更优异的质子传导率与力学强度平衡能力.     

Pervaporation dehydration of ethylene glycol with chitosan–poly(vinyl alcohol) blend membranes: Effect of CS–PVA blending ratios

Chitosan–poly(vinyl alcohol), CS–PVA, blended membranes were prepared by solution casting of varying proportions of CS and PVA. The blend membranes were then crosslinked interfacially with trimesoyl chloride (TMC)/hexane. The physiochemical properties of the blend membranes were determined using Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), tensile test and contact angle measurements. Results from ATR-FTIR show that TMC has crosslinked the blend membranes successfully, and results of XRD and DSC show a corresponding decrease in crystallinity and increase in melting point, respectively. The crosslinked CS–PVA blend membranes also show improved mechanical strength but lower flexibility in tensile testing as compared to uncrosslinked membranes. Contact angle results show that crosslinking has decreased the surface hydrophilicity of the blend membranes. The blend membrane properties, including contact angle, melting point and tensile strength, change with a variation in the blending ratio. They appear to reach a maximum when the CS content is at 75 wt%. In general, the crosslinked blend membranes show excellent stability during the pervaporation (PV) dehydration of ethylene glycol–water mixtures (10–90 wt% EG) at different temperatures (25–70 °C). At 70 °C, for 90 wt% EG in the feed mixture, the crosslinked blend membrane with 75 wt% CS shows the highest total flux of 0.46 kg/(m² h) and best selectivity of 986. The blending ratio of 75 wt% CS is recommended as the optimized ratio in the preparation of CS–PVA blend membranes for pervaporation dehydration of ethylene glycol.     

支化型聚苯并咪唑高温质子交换膜的制备与性能研究

通过引入1,3,5-苯三酸作为支化结构,制备了一种新型的支化型聚醚聚苯并咪唑(OPBI)高温燃料电池质子交换膜,并对支化OPBI质子交换膜的磷酸掺杂率、抗氧化稳定性、机械性能以及质子传导率等一系列性质进行了深入研究.与线型聚苯并咪唑(PBI)相比,支化OPBI具有独特的三维空间结构,极大地提高了磷酸掺杂量,随着支化度的提高,磷酸掺杂率和质子传导率随之提高.支化度为9%时,聚合物的磷酸掺杂率高达9.2 PRU?1,质子传导率达到0.0314 S/cm.此外,支化OPBI膜的溶解性较线型PBI也有较大的改善,进一步提高了聚合物的可加工性.同时,支化OPBI膜的热稳定性和抗氧化稳定性也得到了一定程度的提高,虽然机械性能略有下降,但仍能满足高温燃料电池的使用要求.     

Preparation and characterization of PVDF‐based blend membranes as polymer electrolyte membranes in fuel cells: Study of factor affecting the proton conductivity behavior

There is a huge demand especially for polyvinylidene fluoride (PVDF) and its copolymers to provide high performance solid polymer electrolytes for use as an electrolyte in energy supply systems. In this regard, the blending approach was used to prepare PVDF‐based proton exchange membranes and focused on the study of factor affecting the ir proton conductivity behavior. Thus, a series of copolymers consisting of poly (methyl methacrylate) (PMMA), polyacrylonitrile (PAN), and poly(2‐acrylamido‐2‐methyl‐l‐propanesulfonic acid) (PAMPS) as sulfonated segments were synthesized and blended with PVDF matrix in order to create proton transport sites in PVDF matrix. It was found that addition of PMMA‐co‐PAMPS and PAN‐co‐PAMPS copolymers resulted in a significant increase in porosity, which favored the water uptake and proton transport at ambient temperature. Furthermore, crystallinity degree of the PVDF‐based blend membranes was increased by addition of the related copolymers, which is mainly attributed to formation of hydrogen bonding interaction between PVDF matrix and the synthesized copolymers, and led to a slight decrease in proton conductivity behavior of blend membranes. From impedance data, the proton conductivity of the PVDF/PMMA‐co‐PAMPS and PVDF/PAN‐co‐PAMPS blend membranes increases to 10 and 8.4 mS cm⁻¹ by adding only 50% of the related copolymer (at 25°C), respectively. Also, the blend membranes containing 30% sulfonated copolymers showed a power density as high as 34.30 and 30.10 mW cm⁻² at peak current density of 140 and 79.45 mA cm⁻² for the PVDF/PMMA‐co‐PAMPS and PVDF/PAN‐co‐PAMPS blend membranes, respectively. A reduction in the tensile strength was observed by the addition of amphiphilic copolymer, whereas the elongation at break of all blend membranes was raised.     

Tough crystalline blends of polylactide with block copolymers of ethylene glycol and propylene glycol

The effect of crystallinity of polylactide (PLA) on the structure and properties of tough PLA blends with PEG-b-PPG-b-PEG block copolymers was studied. PLA was melt blended with a set of the copolymers with varying ratio of the hydrophilic (PEG) and hydrophobic (PPG) blocks. Although the blend phase structure depended on the copolymer molar mass and PEG content, as well as on the copolymer concentration in the blend, crystallinity also played an important role, increasing the copolymer content in the amorphous phase and enhancing phase separation. The influence of crystallinity on the thermal and mechanical properties of the blends depended on the copolymer used and its content. The blends, with PLA crystallinity of 25 ÷ 34 wt%, exhibited relatively high glass transition temperature ranging from 45 to 52 °C, and melting beginning above 120 °C. Although with a few exceptions crystallinity worsened the drawability and toughness, these properties were improved with respect to neat crystalline PLA in the case of partially miscible blends, in which fine liquid inclusions of the modifier were dispersed in PLA rich matrix. About 20-fold increase of the elongation at break and about 4-fold increase of the tensile impact strength were reached at a small content (10 wt%) of the modifier. Moreover, crystallinity decreased oxygen and water vapor transmission rates through neat PLA and the blend, and the barrier property for oxygen of the latter was better than that of neat polymer.     

直接甲醇燃料电池新型聚合物膜的研究

通过溶液共混方法 ,制备了聚偏氟乙烯与聚苯乙烯磺酸 (PVDF_PSSA)、聚偏氟乙烯与Nafion(PVDF_Nafion)两种共混膜 .研究了膜组成对膜电导率和甲醇透过率的影响 .与Nafion 1 1 7膜相比 ,PVDF_Nafion共混膜在Nafion含量为 2 5wt%时 ,电导率σ下降 2个数量级 ,而甲醇透过率P却降低 3个数量级 .若以 (σ/P)为综合指标 ,则PVDF_Nafion共混膜和PVDF_PSSA共混膜的综合性能分别比Nafion 1 1 7膜高约 4 0倍、1 6倍     

Synthesis and characterization of bisulfonated poly(vinyl alcohol)/graphene oxide composite membranes with improved proton exchange capabilities

Composite membranes based on poly(vinyl alcohol) (PVA) and graphene oxide (GO) were prepared by solution-casting method to be used as proton exchange membranes (PEMs) in fuel cell (FC) applications. Bisulfonation was employed as a strategy to enhance the proton conductivity of these membranes. First, a direct sulfonation of the polymer matrix was accomplished by intra-sulfonation of the polymer matrix with propane sultone, followed by the inter-sulfonation of the polymer chains using sulfosuccinic acid (SSA) as a crosslinking agent. Furthermore, the addition of graphene oxide (GO) as inorganic filler was also evaluated to enhance the proton-conducting of the composite membranes. These membranes were fully characterized by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and tensile tests. Besides, the proton conductivity of these membranes in a fully hydrated state was also analyzed by electrochemical impedance spectroscopy (EIS). The effect of the intra- and inter-sulfonation of the polymer matrix on the structural, morphological, thermal and mechanical properties of the membranes were determined. Increasing the density of sulfonic acid groups in the membranes resulted in a trade-off between a better proton conductivity (improving from 0.26 to 1.00 mS/cm) and a decreased thermal and mechanical stability. In contrast, the incorporation of GO nanoparticles into the polymer matrix improved the thermal and mechanical stability of both bisulfonated composite membranes. The proton conductivity appreciably increased by the combination of bisulfonation and introduction of GO nanoparticles into the polymer matrix. The sPVA/30SSA/GO composite membrane exhibited a proton conductivity of 1.95 mS/cm at 25 °C. The combination of the GO nanoparticles with the chemical bisulfonation approach of PVA allows thus assembling promising proton exchange membrane candidates for fuel cell applications.     

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis,characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m² hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.     

Poly(vinyl alcohol)/polyelectrolyte complex blend membrane for pervaporation dehydration of isopropanol

Poly(vinyl alcohol) (PVA) was blended with soluble polyelectrolyte complex (PEC) made from poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa). Crystallinity, thermal transition, and thermal stability of the PVA/PEC blends were characterized by using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermal gravity analysis (TGA), respectively. Surface morphology, cross-section and phase structure of the blend membranes were examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Surface hydrophilicity and swelling behavior of the blend membranes were examined by water contact angle (CA) and swelling tests. Blend membranes were subjected to isopropanol dehydration, and effects of blend composition, feed composition and feed temperature on pervaporation performance are discussed in terms of phase structures of blend membranes. A performance of J = 1.35 kg/m² h, α = 1002, was obtained for blend membrane containing 50 wt% PEC in dehydrating 10 wt% water–isopropanol at 70 °C.     

Poly(lactic acid)/(styrene‐ethylene‐butylene‐styrene)‐g‐maleic anhydride copolymer/sepiolite nanocomposites: Investigation of thermo‐mechanical and morphological properties

In this study, sepiolite nanoclay is used as reinforcing agent for poly(lactic acid) (PLA)/(styrene‐ethylene‐butylene‐styrene)‐g‐maleic anhydride copolymer (SEBS‐g‐MA) 90/10 (w/w) blend. Effects of sepiolite on thermal behavior, morphology, and thermomechanical properties of PLA/SEBS‐g‐MA blend were investigated. Differential scanning calorimetry results showed 7% improvement in crystallinity at 0.5 wt% of sepiolite. The nanocomposite exhibited approximately 36% increase in the tensile modulus and 17% increase in toughness as compared with the blend matrix at 0.5 and 2.5 wt% of sepiolite respectively. Field emission scanning electron microscopy and transmission electron microscopy images exhibited sepiolite‐induced morphological changes and dispersion of sepiolite in both PLA and SEBS‐g‐MA phases. Dynamic mechanical analysis and wide angle X‐ray diffraction present evidences in support of the reinforcing nature of sepiolite and phase interaction between the filler and the matrix. This study confirms that sepiolite can improve tensile modulus and toughness of PLA/SEBS‐g‐MA blend.     

SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜研究

通过在磺化聚醚醚酮(SPEEK,DS=61.68%)中分别混入酚酞型聚醚砜(PES-C)、磺化酚酞型聚醚砜(SPES-C,DS=53.7%)制备出SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜.结果表明,共混的两种聚合物之间均具有较好的相容性.PES-C、SPES-C的混入能有效降低膜的溶胀及甲醇透过,且随着共混量的增加,这种作用越趋明显.纯SPEEK膜在75℃左右溶解,而SPEEK/PES-C(30wt%)、SPEEK/SPES-C(30wt%)共混膜在80℃时溶胀度仅为22.5%、26.32%.在室温至80℃范围内,纯SPEEK及共混膜的甲醇透过系数都在10-7cm2.s-1数量级上,远小于Nafion115膜.在饱和湿度下,温度大于90℃时,SPEEK/PES-C(20wt%)共混膜电导率超过Nafion115膜;温度大于110℃时,SPEEK/SPES-C(30wt%)共混膜电导率与Nafion115膜相当,达到0.11S.cm-1.高电导率,低透醇系数以及明显提高了的可使用温度表明该类共混膜有望在DMFC中使用.     

Fabrication and optimization of proton conductive polybenzimidazole electrospun nanofiber membranes

Phosphoric acid (PA)–doped polybenzimidazole (PBI) proton exchange membranes have received attention because of their good mechanical properties, moderate gas permeability, and superior proton conductivity under high temperature operation. Among PBI‐based film membranes, nanofibrous membranes withstand to higher strain because of strongly oriented polymer chains while exhibiting higher specific surface area with increased number of proton‐conducting sites. In this study, PBI electrospun nanofibers were produced and doped with PA to operate as high temperature proton exchange membrane, while changes in proton conductivity and morphologies were monitored. Proton conductive PBI nanofiber membranes by using the process parameters of 15 kV and 100 μL/h at 15 wt% PBI/dimethylacetamide polymer concentration were prepared by varying PA doping time as 24, 48, 72, and 96 hours. The morphological changes associated with PA doping addressed that acid doping significantly caused swelling and 2‐fold increase in mean fiber diameter. Tensile strength of the membranes is found to be increased by doping level, whereas the strain at break (15%) decreased because of the brittle nature of H‐bond network. 72 hour doped PBI membranes demonstrated highest proton conductivity whereas the decrease on conductivity for 96‐hour doped PBI membranes, which could be attributed to the morphological changes due to H‐bond network and acid leaking, was noted. Overall, the results suggested that of 72‐hour doped PBI membranes with proton conductivity of 123 mS/cm could be a potential candidate for proton exchange membrane fuel cell.     

Effect of polyaniline (PANI) on Poly(vinylidene fluoride-co-hexaflouro propylene) (PVDF-co-HFP) polymer electrolyte membrane prepared by breath figure method

Poly(vinylidene fluoride-co-hexaflouro propylene) is a well-known material for polymer electrolyte membranes (PEMs) due to its low cost, high mechanical integrity and excellent chemical resistance; however, its pure form has limited characteristics that require further modification to achieve optimum results. Therefore, the different dosages of polyaniline (PANI) (10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) were incorporated into PVDF-HFP blend to fabricate PVDF-HFP/PANI polymer electrolyte membrane by using breath-figure method. The FTIR peaks of PVDF-HFP and PVDF-HFP/PANI membrane confirms the successful incorporation of PANI into PVDF-HFP blend, while TGA, DSC and XRD analysis shows the PANI effect on stability and ionic conductivity of PVDF-HFP membrane. The PVDF-HFP/PANI membrane with 30 wt% PANI found superior with the highest porosity of 83%, electrolyte uptake of 270% and ionic conductivity of 1.96 mS cm⁻¹; however, the other concentrations of PANI were also effective and enhanced the performance of PVDF-HFP membrane. This shows the improved performances of PVDF-HFP membrane were attributed to successful incorporation of PANI and the proposed membrane can be a suitable alternative PEM or a separator for energy devices.     

Performance enhancement of thin‐film composite membranes in water desalination process by wood sawdust

In this study, polysulfone/wood sawdust (PSf/WSD) mixed matrix membrane (MMM) was prepared as a novel substrate layer of thin‐film composite (TFC) membrane in water desalination. The main aim was to evaluate how different amounts of WSD (0‐5 wt%) and PSf concentrations (12‐16 wt%) in the porous substrate affect the properties of the final TFC membranes in the separation of organic and inorganic compounds. Morphological and wettability studies demonstrated that the addition of small amount of WSD (less than or equal to 1 wt%) in the casting solution resulted in more porous but similar hydrophobic substrates, while high loading (greater than or equal to 2 wt%) of WSD not only changed the substrate wettability and morphology but also increased and decreased the swelling and mechanical properties of substrate layer. Therefore, PA layer formed thereon displayed extensively varying film morphology, interfacial properties, and separation performance. Based on approximately stable permeate flux (ASPF) and apparent salt rejection efficiency (ASRE), the best TFC membrane was prepared over the substrate with 12 to 14 wt% of PSf and around 0.5 to 1 wt% of WSD. Although notable improvements in permeate flux were obtained by adding a small amount of sawdust, the results clearly indicate that the salt rejection mechanism of TFC membrane was different from the glycerin rejection mechanism. Furthermore, durability results of TFC membranes showed that in continuous operation for 30 days, TFC‐14/0.5 and TFC‐14/01 have the maximum plateau levels of stable permeate flux and salt rejection among the all TFC membranes.     

Structural and electrical properties of polyvinyl alcohol (PVA):Methyl cellulose (MC) based solid polymer blend electrolytes inserted with sodium iodide (NaI) salt

This paper studies the structural and electrical properties of solid polymer blend electrolytes based on polyvinyl alcohol (PVA) and methylcellulose (MC) incorporated with sodium iodide (NaI). The polymer electrolyte films were assembled through a solution casting technique. The host matrix, which is doped with different NaI salt concentrations between 10 and 50 wt%, utilizes the most amorphous blend compositions (60 wt% Polyvinyl alcohol and 40 wt% methylcellulose). The structural behaviour of the electrolyte films was examined utilizing X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) techniques. The semi crystalline nature of PVA:MC with inserted NaI was derived from the X-ray diffraction studies, while the XRD analysis suggests that the highest ion conductive sample displays the minimum crystalline nature. The interaction between polymer blends and inserted salt was conceived from the FTIR investigation. Shifting of peaks and variation in the intensity of FTIR bands was detected. To investigate the structural properties and calculate the degree of crystallinity of the films, the (XRD) technique was employed, while electrical impedance spectroscopy (EIS) was utilized for studying the conductivity of the samples. In order to comprehend all of the electrical properties of the ion-conducting systems, the EIS outcome of each electrolyte was matched with Equivalent Electrical Circuits (EEC) s. Ion transport parameters including mobility, carrier density and diffusion are well assessed for the samples and the dielectric properties were compared with the conductivity measurement. At lower frequencies, the dielectric constant was elevated and dielectric loss was detected. Loss tangent and electric modulus plots were used to study the relaxation nature of the samples. The highest ambient temperature conductivity of PVA loaded 50 wt% of NaI was determined to be 1.53 × 10⁻⁵ S/cm. The loss tangent relaxation peak shifts towards high-frequency side which indicates the decrease of relaxation time and faster ion dynamics.     

Novel polyethersulfone-cellulose composite thin film using sustainable empty fruit bunches from Elaeis guineensis for methylene blue removal

The consumption of the polymeric membrane is increased over the years due to the high demand from the industries. This work attempts to evaluate the performance of polyethersulfone (PES) membrane incorporated with cellulose nanofibrils (CNF), which can be extracted from empty fruit bunches generated from palm oil mills. PES/CNF/polyvinylpyrrolidone (PVP) blend membranes were fabricated using phase inversion method under the following conditions: 16 to 24 wt% PES, 0.2 to 1.2 wt% CNF and 0.3 to 1.0 wt% PVP. Response Surface Methodology (RSM) was employed to optimize the composition of this composite membrane. 80.9 L/m².hr permeate flux and 62.3% MB rejection were obtained at a composition of 18.0202 wt% PES, 0.2000 wt% CNF, and 0.4980 wt% PVP. ANOVA for the models showed that the Prob.>F values for permeate flux and MB rejection were 0.0011 and 0.001, which indicated the significant effect of CNF on the performance of the PES composite membrane.     

The effect of halloysite nanotubes and N,N′-ethylenebis (stearamide) on morphology and properties of polylactide nanocomposites with crystalline matrix

Poly(lactide)/halloysite nanotubes (PLA/HNT) nanocomposites with crystalline matrix were obtained by cold crystallization and examined. Neat HNT and HNT treated with N,N′- ethylenebis(stearamide) (EBS) were used as nanofillers. Reference materials, PLA and PLA/EBS blend, prepared in the same way, were also considered. The influence of HNT and/or EBS content on the crystallinity and morphology of PLA matrix, as well as on the dynamic mechanical and optical properties of the materials, was determined.The nanocomposites contained well-distributed HNT, with only occasional agglomerates. HNT, EBS-treated HNT and EBS influenced the morphology of the crystalline PLA matrix and the amounts of the disorder α’ (termed also δ) and order α crystallographic forms of PLA. Crystallinity increased stiffness of the materials compared to their counterparts with the amorphous matrix. Owing to the crystallinity and the presence of the nanofillers, the storage modulus at 20 °C and 60 °C increased by up to 30 and 60%, respectively, compared to neat amorphous PLA. Interestingly, at lower nanofiller content the crystalline nanocomposites with EBS were more transparent than neat crystalline PLA.     

Modification and characterization of semi-crystalline poly(vinyl alcohol) with interpenetrating poly(acrylic acid) by UV radiation method for alkaline solid polymer electrolytes membrane

Semi-crystalline poly(vinyl alcohol) was modified by UV radiation with acrylic acid monomer to get interpenetrating poly(acrylic acid) modified poly(vinyl alcohol), PVAAA, membrane. The stability of various PVAAA membranes in water, 2 M CH₃OH, 2 M H₂SO₄, and 40 wt% KOH aqueous media were evaluated. It was found that the stability of PVAAA membrane is stable in 40 wt% KOH solution. The PVAAA membranes were characterized by differential scanning calorimetry, X-ray diffraction, and thermogravimetry analysis. These results show that (1) the crystallinity in PVAAA decreased with increasing the content of poly(acrylic acid) in the PVAAA membranes. (2) The melting point of the PVAAA membrane is reduced with increasing the content of poly(acrylic acid) in the membrane. (3) Three stages of thermal degradation were found for pure PVA. Compared to pure PVA, the temperature of thermal degradation increased for the PVAAA membrane. The various PVAAA membranes were immersed in KOH solution to form polymer electrolyte membranes, PVAAA-KOH, and their performances for alkaline solid polymer electrolyte were conducted. At room temperature, the ionic conductivity increased from 0.044 to 0.312 S/cm. The result was due to the formation of interpenetrating polymer chain of poly(acrylic acid) in the PVAAA membrane and resulting in the increase of charge carriers in the PVA polymer matrix. Compared to the data reported for different membranes by other studies, our PVAAA membrane are highly ionic conducting alkaline solid polymer electrolytes membranes.     

Polymer blend membranes of sulfonated poly(arylene ether ketone) for direct methanol fuel cell

The blend membranes of sulfonated poly(arylene ether ketone) (sPAEK) (IEC = 1.0 mequiv./g)/Nafion^® and the blend membranes of sPAEK (IEC = 1.0 mequiv./g)/sPAEK (IEC = 1.7 mequiv./g) were prepared. sPAEK with low IEC was introduced to reduce the methanol permeability through the membrane. Morphology, water uptake, proton conductivity and methanol permeability of the blend membranes were investigated by SEM, AFM, AC impedance spectroscopy and permeability measuring instrument. The cross-sections of blend membranes showed phase-separated morphologies. The effect of phase-separated morphology on the properties of blend membranes was investigated. The properties like water uptake, proton conductivity, and methanol permeability of sPAEK/Nafion^® blend membranes showed similar values with sPAEK and properties of sPAEK/sPAEK blend membranes showed intermediate values of two polymers due to the difference in morphology of the blend membranes. sPAEK/sPAEK blend membranes showed relatively high proton conductivity and lowered methanol permeability compared to Nafion^®. sPAEK/sPAEK blend membranes could be a competent substitution for Nafion^®.     

A facile synthesis of cellulose acetate reinforced graphene oxide nanosheets as proton exchange membranes for fuel cell applications

In this work, for the first time, a simple casting process is used to create an efficient and highly stable cellulose acetate (CA) based membrane with dispersive graphene oxide nanosheets (GO). The successful preparation of GO and its integration into the polymer matrix was verified by structural and morphological characterization using FTIR, TEM, SEM, and XRD. Furthermore, the impact of GO nanosheets and their content on the composite membranes' physicochemical properties is investigated. The water uptake increased up to 24% as the concentration of GO increased, while the ion exchange capacity increased threefold compared to the blank CA membrane. Additionally, increasing GO loading also enhanced the proton conductivity and the tensile strength of the developed membranes. The homogeneous CA/GO nanocomposite membranes with GO filler amounts ranging from 0.3 to 0.8 wt% were found to have excellent proton conductivity varying from 9.2 to 15.5 mS/cm compared to 6.94 mS/cm for Nafion 212. Further, as systematically studied and compared in membrane performance, the overall power density of the membrane electrode assembly (MEA) with GO content was increased up to 519 mW/cm² compared to 401 mW/cm² for Nafion 212 with significantly lower cost. The encouraging outcomes of this study pave the way for a simple, environmentally friendly, and cost-effective approach for developing nanocomposite membranes for application in PEMFCs.