Micro and nano cellular amorphous polymers (PMMA, PS) in supercritical CO2 assisted by nanostructured CO2-philic block copolymers - One step foaming process

Microcellular foaming of commodity amorphous polymers, poly(methyl methacrylate) (PMMA), and poly(styrene) (PS) was studied in supercritical CO₂ via a batch one-step process in the presence of block copolymers able to change their foaming behaviour and therefore the porous structures. Triblock (styrene-co-butadiene-co-methylmethacrylate SBM, methylmethacrylate-co-butylacrylate-co-methylmethacrylate MAM) terpolymers were blended to PS or PMMA by extrusion. They showed advantages compared to classical PS-PMMA polymer blends in terms of cell size control and reduction of cell size. Foaming is carried out on bulk injection molded samples which were saturated under high pressures of CO₂ (300 bars) at different temperatures (25° C to 80 °C) and different depressurization rates (pressure drop rates from 150 bar/min to 12 bar/min). Very distinct cellular structures and densities were controlled by varying either the copolymer type or the foaming conditions (T,P). Cell sizes ranged from 0.2 μm to 200 μm, and densities from 0.30 g/cm³ to 1 g/cm³ in the polymers considered. Particularly, when triblock copolymers were able to self organize (nanostructuring) in a polymer matrix, they became phase separated at a nanometer level, presenting nanostructured polymers matrixes. To conclude the study, a possible nanostructuring mechanism is suggested based on the interplay between rubbery and highly CO₂-philic blocks/rigid and less CO₂-philic blocks. It is demonstrated that block copolymer additives are a good pathway towards micro and ultra microcellular supercritical CO₂ foaming of amorphous polymers.     

Gas foaming of segmented poly(ester amide) films

Biodegradable segmented poly(ester amide)s, based on dimethyl adipate, 1,4-butanediol and N,N′-1,2-ethanediyl-bis[6-hydroxy-hexanamide], with two distinct melting transitions were gas foamed using carbon dioxide (CO₂). Polymer films were saturated with CO₂ at 50 bar for 6 h after which the pressure was released. The samples were immersed in octane at the desired temperature after which foaming started immediately. Just above the lower melt transition the polymers retain adequate mechanical properties and dimensional stability, while the chain mobility increased sufficiently to nucleate and expand gas cells during the foaming process. In this way semi-crystalline poly(ester amide)s can be gas foamed below the flow temperature.Two poly(ester amide)s with 25 mol% (PEA2,5-25) and 50 mol% (PEA2,5-50) of bisamide segment content were foamed at 70 and 105 °C, respectively. The storage modulus (G′) of both pure polymers at the onset foaming temperature is 50-60 MPa. Closed-cell foams were obtained with a maximum porosity of ∼90%. The average pore size of PEA2,5-25 ranges from 77 to 99 μm. In contrast, the average pore size of PEA2,5-50 is in between 2 and 4 μm and can be increased to 100 μm by lowering the CO₂ saturation pressure to 20 bar. The porosity of PEA2,5-50 foams using this saturation pressure decreased to 70%.     

Solubility and diffusivity of CO2 in carboxylated polyesters

The solubility of CO₂ in saturated polyester resins at different temperatures (306 and 343 K) and pressures (0.1-30 MPa) has been measured using a magnetic suspension balance. The solubility data were used for estimating the binary diffusion coefficients. The results show a good solubility of CO₂ in polymers, up to 0.64 g CO₂/g polymer. The diffusion coefficients of supercritical CO₂ in polymers have generally high values and are in the range from 0.156 × 10⁻⁸ to 10.38 × 10⁻⁸ cm²/s. DSC and XRD analyses of the semi-crystalline polymer samples indicate that amorphous degree of polymers after exposure to CO₂ is increased. The observed structural effects are dependent on pressure, temperature and time of exposure to CO₂.     

Solid-state supercritical CO2 foaming of PCL and PCL-HA nano-composite: Effect of composition, thermal history and foaming process on foam pore structure

In this work we investigated the solid-state supercritical CO₂ (scCO₂) foaming of poly(?-caprolactone) (PCL), a semi-crystalline, biodegradable polyester, and PCL loaded with 5 wt% of hydroxyapatite (HA) nano-particles.In order to investigate the effect of the thermal history and eventual residue of the crystalline phase on the pore structure of the foams, samples were subjected to three different cooling protocols from the melt, and subsequently foamed by using scCO₂ as blowing agent. The foaming process was performed in the 37-40 °C temperature range, melting point of PCL being 60 °C. The saturation pressure, in the range from 10 to 20 MPa, and the foaming time, from 2 to 900 s, were modulated in order to control the final morphology, porosity and pore structure of the foams and, possibly, to amplify the original differences among the different samples.The results of this study demonstrated that by the scCO₂ foaming it was possible to produce PCL and PCL-HA foams with homogeneous morphologies at relatively low temperatures. Furthermore, by the appropriate combination of materials properties and foaming parameters, we prepared foams with porosities in the 55-85% range, mean pore size from 40 to 250 μm and pore density from 10⁵ to 10⁸ pore/cm³. Finally, we also proposed a two-step depressurization foaming process for the design of bi-modal and highly interconnected foams suitable as scaffolds for tissue engineering.     

Batch foaming of SAN/clay nanocomposites with scCO2: A very tunable way of controlling the cellular morphology

This paper aims at elucidating some important parameters affecting the cellular morphology of poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposite foams prepared with the supercritical CO₂ technology. Prior to foaming experiments, the SAN/CO₂ system has first been studied. The effect of nanoclay on CO₂ sorption/desorption rate into/from SAN is assessed with a gravimetric method. Ideal saturation conditions are then deduced in view of the foaming process. Nanocomposites foaming has first been performed with the one-step foaming process, also called depressurization foaming. Foams with different cellular morphology have been obtained depending on nanoclay dispersion level and foaming conditions. While foaming at low temperature (40 °C) leads to foams with the highest cell density (∼10¹²-10¹⁴ cells/cm³), the foam expansion is restricted (d∼0.7-0.8 g/cm³). This drawback has been overcome with the use of the two-step foaming process, also called solid-state foaming, where foam expansion occurs during sample dipping in a hot oil bath (d∼0.1-0.5 g/cm³). Different foaming parameters have been varied, and some schemes have been drawn to summarize the characteristics of the foams prepared - cell size, cell density, foam density - depending on both the foaming conditions and nanoclay addition. This result thus illustrates the huge flexibility of the supercritical CO₂ batch foaming process for tuning the foam cellular morphology.     

Elaboration and characterization of porous granules based on waste glass

The evolutions of the world today and the population increase have resulted in pollution and human wastes, which contaminate the environment and adversely affect the human's quality of life.All forms of food and drink packages, made of paper, plastic foam, aluminum and glass, are designed for the consumers' convenience. After being used, these packages are discarded as garbage and have today become a social problem.It is in this context that our work for obtaining a building material (foam glass granules) that is much lighter is registered with the properties of heat insulation and acoustic improved based on cullet in order to recycle it and for improving the present laws about the waste products in closed circuit (finished products → waste products → finished products).Investigations have shown that grinding waste glass to particle size less than 0.1 mm and adding 1% of Ca CO₃ content provide the production of material with the following properties: particle density of 0.5 g/cm³, strength of 17.50 MPa and water adsorption of 95%, with the temperature for foaming ranges determined at 850 °C. The microstructures are homogenous, with pore sizes of up to 2 mm. The foam glass is counted among the new glass products meeting certain requirements on comfort, in particular in the building industry (thermal and acoustic insulation). The product obtained presents excellent thermal (λ = 0,031 W/m°C) and acoustic (R = 15 dB) properties.     

Recovery of triglycerides from used frying oil by extraction with liquid and supercritical ethane

The extraction of triglycerides from used frying oil with liquid and supercritical ethane has been studied in a semibatch system at different temperatures (25-80 °C) and pressures (150-250 kg/cm²). It has been found that isobaric decreases of temperature and isothermal increases of pressure lead to both increasing extraction yields and decreasing separation efficiencies. Lipid fractions recovered in the high density region had acceptable concentrations of polar compounds.Results with ethane have been compared to those reported for CO₂ in earlier works. At similar reduced densities of the solvents, oil solubility in ethane was higher than in CO₂, being the separation efficiency of polar fractions slightly better when using ethane.The extraction process was further analyzed in a packed countercurrent column. At optimum conditions (250 kg/cm², 25 °C, and solvent-to-oil ratio 45 g:g) about 85% of the triglycerides were recovered, being 11.2% the polar content of the triglyceride fraction recovered.     

Nafion 115/zirconium phosphate composite membranes for operation of PEMFCs above 100 °C

Composite Nafion/zirconium phosphate membranes were investigated for high temperature operation of proton exchange membrane fuel cells (PEMFCs). The composite membranes were prepared via impregnation of Nafion films (either commercial Nafion 115 or recast Nafion) with zirconyl chloride and 1 M phosphoric acid at 80 °C. An MEA employing a composite membrane prepared starting from commercial Nafion 115 gave a H₂/O₂ PEMFC performance of about 1000 mA/cm² at 0.45 V at a temperature of 130 °C and a pressure of 3 bar; this result compares very favorably with the performance of an MEA based on commercial unmodified Nafion, which gave only 250 mA/cm² at 0.45 V when operated under the same conditions of temperature and pressure. Similar experiments performed with recast Nafion and recast Nafion/zirconium phosphate composites confirmed an analogous improvement of performance of the composite membranes over the unimpregnated ones. In this case, the composite recast Nafion/zirconium phosphate gave about 1500 mA/cm² at 0.45 V at a temperature of 130 °C and a pressure of 3 bar. The composite membranes showed stable behavior during time when maintained at 130 °C, while irreversible degradation affected Nafion under the same conditions.     

Hierarchical porous carbons with controlled micropores and mesopores for supercapacitor electrode materials

Various porous carbons were prepared by CO₂ activation of ordered mesoporous carbons and used as electrode materials for supercapacitor. The structures were characterized by using X-ray diffraction, transmission electron microscopy and nitrogen sorption at 77 K. The effects of CO₂ treatment on their pore structures were discussed. Compared to the pristine mesoporous carbons, the samples subjected to CO₂ treatment exhibited remarkable improvement in textural properties. The electrochemical measurement in 6 M KOH electrolyte showed that CO₂ activation leads to better capacitive performances. The carbon CS15A6, which was obtained after CO₂ treatment for 6 h at 950 °C using CMK-3 as the precursor, showed the best electrochemical behavior with a specific gravimetric capacitance of 223 F/g and volumetric capacitance of 54 F/cm³ at a scan rate of 2 mV/s and 73% retained ratio at 50 mV/s. The good capacitive behavior of CS15A6 may be attributed to the hierarchical pore structure (abundant micropores and interconnected mesopores with the size of 3-4 nm), high surface area (2749 m²/g), large pore volume (2.09 cm³/g), as well as well-balanced microporosity and mesoporosity.     

Preparation of a carbon monolith with hierarchical porous structure by ultrasonic irradiation followed by carbonization, physical and chemical activation

A two-step direct and simple method for the preparation of a hierarchical porous carbon monolith with micropores, mesopores and macropores is described. The two stages give more flexibility in the preparation of a porous carbon monolith. In step I a macroporous interconnected carbon monolith is prepared by ultrasonic irradiation during sol-gel polycondensation. The effects of sol-gel temperature, catalyst concentration and ultrasonic power on the structure of the monolith are investigated. In step II, mesopores are induced in the monolith by Ca(NO₃)₂ impregnation followed by CO₂ activation. The effect of activation temperature is also studied. A hierarchical interconnected carbon monolith with mean pore size diameter of 1.2 μm, BET surface area of 624 m²/g, mesopore volume of 0.38 cm³/g and micropore volume of 0.22 cm³/g has been obtained from Ca(NO₃)₂ impregnation of the macroporous carbon monolith followed by CO₂ activation at 850 °C.     

Glycerol desorption from ion exchange and adsorbent resin using supercritical fluid technology: An optimization study

In this study, glycerol desorption from Purolite^® PD206 resin was investigated using conventional and supercritical fluids (SCF) techniques. Untreated biodiesel was purified by dry washing using the resin and, after purification, the glycerol desorption was carried out using absolute ethanol under atmospheric conditions at different mass flows (10-30 g/min) or using ethanol-modified supercritical CO₂ (1:3 molar ratio of ethanol:CO₂), under a pressure of 140 bar, within a temperature range of 106-134 °C and with mass flow rates of 6-34 g/min. The results showed that ethanol is an efficient solvent for this process and that the supercritical desorption is much faster than conventional desorption process. Employing the Response Surface Methodology (RSM) it was found that temperature has the greatest effect on the resin regeneration time using supercritical fluids. Optimum conditions obtained were 106.1 °C and 21.9 g/min, in which the resin was regenerated in only 4.17 min.     

Generation and characterization of carbon nano-fiber-poly(arylene ether sulfone) nanocomposite foams

In this study, carbon nano-fibers (CNFs) were used to increase the compressive properties of poly(arylene ether sulfone) (PAES) foams. The polymer composite pellets were produced by melt blending the PAES resin with CNFs in a single screw extruder. The pellets were saturated and foamed with water and CO₂ in a one-step batch process method. Dynamic mechanical thermal analysis (DMTA) was used to determine the reduced glass transition temperature (T_g) of the CNF-PAES as a result of plasticization with water and CO₂. Sharp transitions were observed as peaks in the tan δ leading to accurate quantitative values for the T_g. By accurately determining the reduced T_g, the foaming temperature could be chosen to control the foam morphology. Foams were produced which ranged in density from 290 to 1100 kg/m³. The foams had cell nucleation densities between 10⁹ and 10¹⁰ cells/cm³, two orders of magnitude higher than unreinforced PAES foam, suggesting that the CNFs acted as heterogeneous nucleating agents. The CNF-PAES foam exhibited improved compressive properties compared to unreinforced PAES foam produced from a similar method. Both the specific compressive modulus and strength increased by over 1.5 times that of unreinforced PAES foam. The specific compressive strength of 59 MPa for the CNF-PAES foam is similar to that of commonly used high performance structural foam, poly(methacrylimide foam).     

Changes in pore structure of anthracite coal associated with CO2 sequestration process

Pore structure changing of coal during the CO₂ geo-sequestration is one of the key issues that affect the sequestration process significantly. To address this problem, the CO₂ sequestration process in an anthracite coal was replicated using a supercritical CO₂ (ScCO₂) reactor. Different coal grain sizes were exposed to ScCO₂ and water at around 40 °C and 9.8 MPa for 72 h. Helium pycnometer and mercury porosimetry provide the density, pore size distribution and porosity of the coal before and after the ScCO₂ treatment. The results show that after exposure to the ScCO₂-H₂O reaction, part of the carbonate minerals were dissolved and flushed away by water which made the true density increased as well as total pore volume and porosity most importantly in the micro-pore range. Hysteresis between mercury intrusion and extrusion was observed. Ink bottle shaped pores can be either damaged or created compared with the ScCO₂ treated coal samples. This suggests that the ScCO₂ treatment most likely increase the volumes of pores in anthracite coal, which also contributed to the increase in porosity of the treated samples. Therefore the CO₂ sequestration into coal appears to have the potential to increase significantly the anthracite microporosity which is very advantageous for CO₂ storage.     

High power supercapacitors using polyacrylonitrile-based carbon nanofiber paper

Porous carbon nanofiber paper has been obtained by one-step carbonization/activation of PAN-based nanofiber paper at temperatures from 700 to 1000 °C in CO₂ atmosphere. The paper was used as supercapacitor electrode without any binder or percolator. At low temperature, e.g., ?900 °C, nitrogen enriched carbons with a poorly developed specific surface area (S_BET ? 400 m²/g) are obtained. In aqueous electrolytes, these carbons withstand high current loads without a noticeable decrease of capacitance, and the normalized capacitance reaches 67 μF/cm². At 10 s time constant, the values of energy and power densities are 3-4 times higher than for activated carbons (AC) presenting higher specific surface area. By carbonization/activation at 1000 °C, subnanometer pores are developed and S_BET = 705 m²/g. Despite moderate BET specific surface area, the capacitance reaches values higher than 100 F/g in organic electrolyte. At high power densities, the nanofiber paper obtained at 1000 °C outperforms the energy density retention of ACs in organic electrolyte. The high power capability of the carbon nanofiber papers in the two kinds of electrolytes is attributed both to the high intrinsic conductivity of the fibers and to the high diffusion rate of ions in the opened mesopores.     

Optimization of total alkannin yields of Alkanna tinctoria by using sub- and supercritical carbon dioxide extraction

The effects of supercritical carbondioxide extraction was investigated to compare previously validated extraction methods on total alkannin yield with Alkanna tinctoria collected form Antalya, Turkey. A two-step process was used; extraction of alkannin derivatives with supercritical CO₂ followed by alkaline hydrolysis of alkannin derivatives. A Box-Behnken exprerimental design was used to evaluate the effect of three variables, pressure (50-350 bar), temperature (30-80 °C) and CO₂ flow (5-20 g min⁻¹) at 1:30 ratio of alkanna root:CO₂ amount. Response surface analysis revealed that the data were adequately fitted to a second-order polynomial model with R² 0.9665 and the most effective variable was pressure (P ≤ 0.05). Optimum conditions were determined as 80 °C, 175 bar, 5 g min⁻¹ CO₂ flow yielding the highest total alkannins (1.47%) which was higher than conventional hexane extraction (1.24%) providing a solvent-free alternative for industrial production.     

Partitioning of drug model compounds between poly(lactic acid)s and supercritical CO2 using quartz crystal microbalance as an in situ detector

Quartz crystal microbalance (QCM) was used as an in situ detector to investigate the potential application in the phase equilibrium determination of supercritical CO₂-drug-polymer systems. CO₂ solubility in two biodegradable polymers, poly(d,l-lactic acid) (d,l-PLA) and poly(l-lactic acid) (l-PLA) was primarily measured at 313.15 K and pressures up to 10.0 MPa. d,l-PLA showed a better CO₂ absorption ability due to its amorphous structure. Four drug model compounds of poor solubility in water, ibuprofen, aspirin, salicylic acid and naphthalene were selected as representatives for the examination of drug uptake in PLA matrices, as well as partition coefficient during supercritical impregnation. It was found that partition coefficients of drugs can reach as high as 10³-10⁴ orders of magnitude and greatly affected by the intermolecular interactions between drugs and PLA. Aspirin exhibited the best partitioning during the supercritical impregnation at pressures of 8.0-10.0 MPa due to the existence of carboxylic acid and acetyl groups. Drug partitioning is additionally related to the drug concentration in ScCO₂, i.e. salicylic acid showed little absorption in PLA according to its poor solubility in ScCO₂ at 7.5-8.0 MPa, whereas the well CO₂-soluble compound, naphthalene, exhibited a moderate partition coefficient although its polarity was different from l-PLA.     

Studies on the interactions of CO2 with biodegradable poly(dl-lactic acid) and poly(lactic acid-co-glycolic acid) copolymers using high pressure ATR-IR and high pressure rheology

Amorphous poly(dl-lactic acid) (P_dlLA) and poly(lactic acid-co-glycolic acid) (PLGA) polymers have been used to fabricate porous scaffolds for tissue engineering applications via a supercritical foaming technique. The chemical composition of the polymers and the morphology (pore size, porosity and interconnectivity) of the scaffolds are crucial because they influence cell filtration, migration, nutrient exchange, degradation and drug release rate. To control the morphology of supercritical foamed scaffolds, it is essential to study the interactions of polymers with CO₂ and the consequent solubility of CO₂ in the polymers, as well as the viscosity of the plasticized polymers. In this paper, we are showing for the first time that well known and useful biodegradable polymers can be plasticized easily using high pressure CO₂ and that we can monitor this process easily via a high pressure attenuated total reflection Fourier transform infrared (ATR-IR) and rheology. High pressure ATR-IR has been developed to investigate the interactions of CO₂ with P_dlLA and PLGA polymers with the glycolic acid (GA) content in the copolymers as 15, 25, 35 and 50% respectively. Shifts and intensity changes of IR absorption bands of the polymers in the carbonyl region (∼1750 cm⁻¹) are indicative of the interaction on a qualitative level. A high pressure parallel plate rheometer has also been developed for the shear viscosity measurements of the CO₂-plastisized polymers at a temperature below their glass transition temperatures. The results demonstrate that the viscosities of the CO₂-plasticized polymers at 35 °C and 100 bar were comparable to the values for the polymer melts at 140 °C, demonstrating a significant process advantage through use of scCO₂. The data from the high pressure rheology and high pressure ATR-IR, combined with the sorption and swelling studies reported previously, demonstrate that the interaction and the solubility of CO₂ in PLGA copolymers is related to the glycolic acid content. As the glycolic acid ratio increases the interaction and consequent solubility of CO₂ decreases. The potential applications of this study are very broad, from tissue engineering and drug delivery to much broader applications with other polymers in areas that may range from composites and polymer synthesis through to injection moulding.     

Phase behavior of the poly(neopentyl methacrylate) + supercritical fluid solvents + neopentyl methacrylate system and CO2 + neopentyl methacrylate mixtures at high pressure

High-pressure phase behaviors are measured for the CO₂ + neopentyl methacrylate (NPMA) system at 40, 60, 80, 100, and 120 °C and pressure up to 160 bar. This system exhibits type-I phase behavior with a continuous mixture-critical curve. The experimental results for the CO₂ + NPMA system are modeled using the Peng-Robinson equation of state. Experimental cloud-point data up to the temperature of 180 °C and the pressure of 2000 bar are presented for ternary mixtures of poly(neopentyl methacrylate) [poly(NPMA)] + supercritical solvents + NPMA systems. Cloud-point pressures of poly(NPMA) + CO₂ + NPMA system are measured in the temperature range of 60-180 °C and to pressures as high as 2000 bar with NPMA concentration of 0.0, 5.2, 19.0, 28.1 and 40.2 wt%. It appears that adding 51.2 wt% NPMA to the poly(NPMA) + CO₂ mixture does significantly change the phase behavior. Cloud-point curves are obtained for the binary mixtures of poly(NPMA) in supercritical propane, propylene, butane, 1-butene, and dimethyl ether (DME). The impact of dimethyl ether concentration on the phase behavior of the poly(NPMA) + CO₂ + x wt% DME system is also measured at temperature of 180 °C and pressure range of 36-2000 bar. This system changes the pressure-temperature (P-T) slope of the phase behavior curves from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as the NPMA concentration increases.     

Continuous extraction of glycerol acetates from their mixture using supercritical carbon dioxide

Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixture of triacetin, diacetin, and monoacetin with a molar ratio of 1:2:1. The extraction was carried out in two stages. In the first stage, a central composite design was used to optimize the four variables of pressure, temperature, liquid CO₂ flow rate, and extraction time at three levels using a semi-continuous, supercritical carbon dioxide extraction setup. The composition of the extract under the predicted optimum conditions (i.e., 109 bar, 56 °C, 0.86 mL min⁻¹, and 61 min) was about 69% triacetin accompanied by only 30% diacetin and no detectable monoacetin. In the second stage, the effect of the two factors, pressure (100, 109, and 140 bar) and liquid CO₂ flow rates of 0.86 and 1.5 mL min⁻¹ measured at average laboratory temperature (27 °C) and pressure (0.89 bar), were studied using a continuous, supercritical carbon dioxide fractionation setup equipped with a glass-bead packed column kept under a thermal gradient of 56-70 °C. The experimental design was organized as a 3 × 2 general factorial design. Under the best conditions (i.e., 140 bar and 1.5 mL min⁻¹), the extraction yield of triacetin and diacetin were 41.8 and 3.0%, respectively, without any detectable monoacetin as verified by GC-FID.     

A polymer electrolyte membrane for high temperature fuel cells to fit vehicle applications

Poly(tetrafluoroethylene) PTFE/PBI composite membranes doped with H₃PO₄ were fabricated to improve the performance of high temperature polymer electrolyte membrane fuel cells (HT-PEMFC). The composite membranes were fabricated by immobilising polybenzimidazole (PBI) solution into a hydrophobic porous PTFE membrane. The mechanical strength of the membrane was good exhibiting a maximum load of 35.19 MPa. After doping with the phosphoric acid, the composite membrane had a larger proton conductivity than that of PBI doped with phosphoric acid. The PTFE/PBI membrane conductivity was greater than 0.3 S cm⁻¹ at a relative humidity 8.4% and temperature of 180 °C with a 300% H₃PO₄ doping level. Use of the membrane in a fuel cell with oxygen, at 1 bar overpressure gave a peak power density of 1.2 W cm⁻² at cell voltages >0.4 V and current densities of 3.0 A cm⁻². The PTFE/PBI/H₃PO₄ composite membrane did not exhibit significant degradation after 50 h of intermittent operation at 150 °C. These results indicate that the composite membrane is a promising material for vehicles driven by high temperature PEMFCs.