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The alkaline stability of N-heterocyclic ammonium (NHA) groups is a critical topic in anion-exchange membranes (AEMs) and AEM fuel cells (AEMFCs). Here, we report a systematic study on the alkaline stability of 24 representative NHA groups at different hydration numbers (λ) at 80 °C. The results elucidate that γ-substituted NHAs containing electron-donating groups display superior alkaline stability, while electron-withdrawing substituents are detrimental to durable NHAs. Density-functional-theory calculations and experimental results suggest that nucleophilic substitution is the dominant degradation pathway in NHAs, while Hofmann elimination is the primary degradation pathway for NHA-based AEMs. Different degradation pathways determine the alkaline stability of NHAs or NHA-based AEMs. AEMFC durability (from 1 A cm-2 to 3 A cm-2 ) suggests that NHA-based AEMs are mainly subjected to Hofmann elimination under 1 A cm-2 current density for 1000 h, providing insights into the relationship between current density, λ value, and durability of NHA-based AEMs.

Two series of aromatic poly(ortho-hydroxyamide)s (poly(o-hydroxyamide)s, HPAs) were prepared by reaction of two diamines, 2,2-bis(3-amino-4-hydroxyphenyl) propane (APA) and 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF), with four aromatic diacid chlorides; terephthaloyl dichloride (TPC), isophthaloyl dichloride (IPC), 2,2-bis[4-chlorocarbonylphenyl)hexafluoropropane (6FC) and 4,4¿-sulfonyldibenzoyl dichloride (DBSC). Amorphous HPAs with high molecular weights (inherent viscosities higher than 0.5 dL/g) and relatively high glass transition temperatures (220¿280 °C) were obtained. Dense membranes of HPAs were able to undergo a thermal rearrangement (TR) process to polybenzoxazoles (ß-TR-PBOs) heating at moderate temperatures (between 250 and 375 °C), and their complete conversion was reached at a temperature below 375 °C, depending on the o-hydroxy diamine moiety, APA and APAF. The ß-TR-PBOs films derived from APAF showed a higher thermal stability and higher Tg than those from APA. Gas separation properties of TR-PBOs membranes were superior to those of their poly(o-hydroxyamide) precursors, particularly for the following gas pairs: O2/N2, CO2/CH4, He/CH4 and He/CO2., The financial support provided, by the Spain's MINECO (MAT2013- 45071-R and MAT2016-76413-C2-1-R and MAT2016-76413-C2-2-R AEI/FEDER, UE and CTQ 2012-31076) is greatly acknowledged. This research was also supported by the Korea Carbon Capture & Sequestration R&D Center (KCRC) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (NRF-2014M1A8A1049305). We are also indebted to the Spanish Junta de Castilla y León for its funding help (project VA248U13). Authors kindly acknowledge Sara Rodriguez for carrying out the gas separation tests and Judit González Jarillo for performing polymer characterization

Anion exchange membrane fuel cells (AEMFCs) have experienced rapid advancement in the past few years due to the discovery of high-performance AEMs and ionomers. Here, we report a series of side-chain-type poly(dibenzbeyl-co-terphenyl piperidinium) (s-PDTP) copolymers as ionomers and membranes for AEMFC applications. The features of aryl ether-free PDTP polymer backbone and pendent ammonium groups endow both high alkaline stability and excellent micromorphology to s-PDTP copolymers. These ion-exchange-capacity (IEC)-controlled s-PDTP membranes possess high OH− conductivity >120 mS cm−1 at 80 °C, reasonable molecular weight (Mw = 150–290 kDa), and excellent ex-situ durability in 1 M NaOH at 80 °C for 1000 h (∼90% conductivity remaining). For ionomer research, s-PDTP ionomers with moderate IEC (∼3.0 mmol g−1) and rational water uptake (∼200%) exhibit optimal AEMFC performance based on a PDTP membrane compared to high-IEC or low-IEC s-PDTP ionomers (>3.4 mmol g−1 or

Though membrane distillation (MD) has been considered as a promising desalination process, it is still required to develop a desirable membrane which has high water flux and long-term stability for practical use in the MD process. In our previous work, thermally rearranged nanofiber membranes (TR-NFMs), which exhibited high water flux (80 kg m−2 h−1) and salt rejection (> 99.99%) as well as outstanding long-term stability (more than 180 h), were first introduced as a promising candidate for MD applications. However, nascent TR-NFM is susceptible to fluctuations in operating conditions due to insufficient liquid entry pressure with water (LEPw). In continuation of our enhanced hydrophobic TR-NFM study, we develop fluorine-containing thermally-rearranged nanofiber membranes (F-TR-NFMs) for MD applications for the first time. F-TR-NFMs showed enhanced hydrophobic properties such as high water contact angle (143°), high LEPw (1.3 bar), and high effective evaporation area (EEA) due to the introduction of fluorine atoms in the backbone of the TR membrane. As the result, the developed F-TR-NFMs exhibited outstanding MD performance (114.8 kg m−2 h−1 of water flux and > 99.99% of salt rejection at feed and permeate temperatures of 80 °C and 20 °C, respectively) and excellent energy efficiency (52.1% at feed and permeate temperatures of 50 °C and 20 °C, respectively). The long-term stability of F-TR-NFM is also investigated over more than 250 h of operation time.

A new nucleophilic monomer (2,2-bis(3-amino-4-hydroxyphenyl)adamantane, ADHAB) having bulky adamantane groups has been synthesized following an efficient synthetic methodology. The main target of this work was to employ a high thermal stable bulky cycloaliphatic moiety as adamantane to obtain aromatic ortho-hydroxypolyimides (poly(o-hydroxyimide)s) able to thermally rearrange to give polybenzoxazole (TR-PBO) materials that could be tested as gas separation membranes. Thus, an array of ortho-acetylcopolyimides, o-acetyl PIs) were prepared by reaction of ADHAB and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (APAF) with 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) via chemical imidization. Copolyimides and homopolyimides showed inherent viscosities ranging from 0.49 to 0.70 dL/g and provided good-quality dense membranes. Glass transition temperatures of these o-acetyl copolyimides were higher as the amount of ADHAB increased. The thermal stability of the adamantane moiety during the TR process was evaluated by directly synthesizing PBOs, which were made from the reaction, and ulterior thermal cyclization, of 2,2-bis(4-chlorocarbonylphenyl)-hexafluoropropane with ADHAB/APAF. TR-PBO membranes made through a thermal treatment at 450 °C for 30 min showed excellent gas separation properties for the CO/CH gas pair with values close to the 2008 Robeson limit., The authors acknowledge financial support provided by Spain’s MINECO (CTQ2013-48406-P, MAT2016-76413-C2-R1, and MAT2016-76413-C2-R2). This research was also supported by the Korea Carbon Capture & Sequestration R&D Center (KCRC) administered through the National Research Foundation of Korea (NRF) funded by the Ministry of S c i e n c e , IC T , a n d Fu t u r e Pl anni n g (NRF - 2014M1A8A1049305). We are also indebted to the Spanish Junta de Castilla y León for funding help (Projects VA248U13 and VA256U13). C. Aguilar-Lugo gratefully acknowledges a CONACYT postdoctoral fellowship (264013).

Recently developed crosslinked-thermally rearranged (XTR) polymeric membranes, which show enhanced gas separation, are applicable for CO2 separation from post-combustion gases. Moreover, the resulting thermally rearranged polybenzoxazole (TR-PBO) structure that is thermally induced from hydroxyl-polyimides (HPI) provides high thermal and chemical resistance, which is favorable for gas separation applications containing condensable gases such as water vapor. Herein, the influence of water vapor on the CO2 capture efficiency was evaluated using XTR poly(benzoxazole-co-imide) (XTR-PBOI) hollow fiber membrane modules which were compared with crosslinked HPI (XHPI) in mixture gas and single gases for CO2 and N2. The results revealed that the permeate CO2 flow rate in the hydrophobic XTR-PBOI module showed enhanced separation performance, whereas the flow rate severely decreased in the relatively hydrophilic XHPI module, reflecting more significant capillary condensation effect in the XHPI membranes. Both membrane modules showed excellent plasticization resistance, and the XTR-PBOI hollow fiber membrane module presented reasonable long-term stability over 240 h.

Sulfonated poly(arylene ether sulfone) (SPAES) copolymers possessing three different dihydroxynaphthalene isomers and a biphenol (BP) moiety were synthesized as membranes for energy generation. Membrane samples of three different weight-based ion exchange capacities (IECw, 1.42, 1.82 and 2.2 meq g−1) were evaluated through a thermal, mechanical and electrochemical analysis. In order to investigate the isomeric effects of naphthalene and BP units in a polymer matrix, their ion transport properties were studied for potential energy generation applications, exemplified by reverse electrodialysis (RED) and polymer electrolyte membrane fuel cell (PEMFC) applications. Interestingly, the prepared polymeric membranes comprised of three different naphthalene isomers or BP exhibited considerably disparate ion transport properties in both RED and PEMFC applications. In RED applications, 2,6-dihydroxynaphthalene containing SPAES showed high Na+ ion permselectivity and low membrane resistance due to the dense membrane structure and linear conformation of the resulting membrane. In addition, despite having the same IECw, a large difference in the electrochemical performance of the membranes was observed due to isomeric effects in the naphthalene containing polymer backbone. Moreover, in PEMFC single cell tests at 80 °C under RH 100% and H2/air feed conditions, the membrane composed of 1,5-dihydroxynaphthalene (IECw=2.2 meq g−1), which had a helical conformation, achieved a promising current density (614 mA cm−2 at 0.6 V) among the tested membranes.

Here, we demonstrate the improved electrochemical performance and stability of end-group cross-linked anion exchange membranes (AEM) for the first time via the introduction of imidazolium groups in poly(arylene ether sulfone) (Imd-PAES). A novel feature of the cross-linking reaction is that basic additives are not required to prevent gelation with the cationic functional groups. In this work, the sodium salt of 3-hydroxyphenylacetylene acted directly as the end-group cross-linker, and it was cross-linked by thermal treatment at 180 °C. The gel fraction and hydroxide conductivity of the cross-linked membranes (XE-Imds) depended on the cross-linking temperature and time. The prepared XE-Imd70 (70 refers to the degree of functionalization) membranes with an ion exchange capacity (IEC) of 2.2 meq g−1 achieved a high hydroxide conductivity (107 mS cm−1). This material also showed good single cell performance (XE-Imd70: 202 mA cm−2 at 0.6 V and a maximum power density of 196.1 mW cm−2) at 80 °C, 100% relative humidity (RH), and improved durability and alkaline stability. The excellent hydroxide conductivity and electrochemical performance of XE-Imd70 was due to the fact that the ion cluster size of XE-Imd membranes was larger (12.1–14 nm) than that of E-Imd (5.5–8.14 nm), indicating that XE-Imd membranes have a closely associated ion-clustered morphology, which was confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) measurements.

In this work, three functional groups were introduced in poly(arylene ether sulfone) membranes to investigate the effects of cationic functional groups in the membranes on reverse electrodialysis performance. Our results showed that controlling the swelling behaviour of the membranes was an important factor for increasing the permselectivity while maintaining their high conductivity.

A comprehensive and fundamental gas transport study of ladder-structured polysilsesquioxanes (LPSQs) was systematically performed by investigating the effects of various alkyl substituents, different copolymer ratios, and UV-irradiation induced photo-crosslinking on gas separations. Overall, LPSQ membranes are more suitable for CO 2 /N 2 and CO 2 /H 2 separations due to a relatively high affinity towards CO 2 as well as rubbery polymer properties. The gas transport in LPSQ membranes was well interpreted by two important parameters, the inter-chain distance and the side chain mobility. A combination of larger inter-chain distance and higher side chain rigidity tends to increase the fractional free volume, resulting in higher gas permeability. Also, it was successfully demonstrated that the separation performance of LPSQ membranes can be predicted by using a logarithmic permeability relationship based on the transport characterization for a series of ladder-structured poly(phenyl- co -methacryloxypropyl)silsesquioxanes. Lastly, the UV-curing process reduced the permeability of LPSQ membranes, increasing the selectivity due to the restricted chain mobility.

Microporous polyvinylidene difluoride (PVDF) hollow fiber membranes were fabricated via a thermally-induced phase separation (TIPS) method using an environmental-friendly hydrophobic solvent, acetyl tributyl citrate (ATBC, tradename Citroflex ® A4 ). To maximize membrane tensile strength, the TIPS method was fully utilized by spinning fibers with high polymer content. It was observed that the fiber quality was significantly affected by the dope and bore flow rates and compositions, and an appropriate spinning range was established. The prepared membranes were subsequently stretched to tune the porosity, mean pore size, permeability, tensile strength, and fiber strain. A design of experiment (DOE) analysis was conducted using a 3-factor quadratic model to optimize the stretching conditions and to understand the effects of the parameters and interactions thereof. The permeability of the stretched membranes improved by a factor of 35 (15.1–538 L m −2 h −1 bar −1 ), and the tensile strength increased from 7.2 MPa to 8.4 MPa at the expense of the fiber strain. The DOE analysis revealed that the stretching ratio positively affects the permeability and porosity but decreases the fiber strain. On the other hand, it was determined that the stretching temperature positively influences the permeability and fiber strength. The stretched membranes exceeded the PVDF performance upper bound prepared by the TIPS method. The membranes were primarily in the α-phase polymorph, and stretching the fibers up to 40% at 90 °C did not induce any detectable β-phase crystals. The proposed preparation method offers a feasible and sustainable alternative to fabricate hollow fibers membranes with high tensile strength and high permeability.

A novel bulky and rigid ortho-hydroxyl diamine, 3,3′-diamino-5,5′,6,6′-tetramethyl-[1,1′-biphenyl]-2,2′-diol (TMBDA), was synthesized for gas separation membranes in this study. The chemical structure of TMBDA with four methyl groups and a fixed twist biphenyl center was rationally designed, and consequently presented a superior energy barrier of rotation, which efficiently suppressed chain motion and enhanced polymer rigidity. Four types of TMBDA-based polyimides (PIs) were prepared with two commercially available dianhydrides, i.e., 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and pyromellitic dianhydride (PMDA), from two different synthetic routes, azeotropic and chemical imidization. Thermally rearranged (TR) polymers were obtained from TMBDA-based PIs by thermal treatment at various temperatures. Thermal properties and physicochemical characteristics of TMBDA-based PIs and TR polymers were investigated. The resulting polymers exhibited high glass transition temperatures (Tg) and contorted backbone structures with three discrete d-spacing values, where the smallest interchain d-spacing was located between the kinetic diameters of H2 and CH4 molecules. Moreover, TMBDA-based TR polymers showed outstanding performances in hydrogen separation with comparable H2 permeability and higher selectivity than reported TRs. For instance, 6F-TM-Ac-425 exhibited a H2 permeability of 325 Barrer with H2/CH4 and H2/N2 selectivities of 50 and 39, respectively, approaching to the 2008 Robeson upper bound.

A series of end-group cross-linked membranes (Az-XESPSN) were prepared by click reaction to investigate the effects of cross-linking on the morphology and proton transport properties of proton exchange membranes. The morphological transformations resulting from thermal annealing and cross-linking were observed by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared to the non-cross-linked ESPSN membranes, the Az-XESPSN membranes exhibited lower water uptake and improved mechanical and chemical stabilities. In addition, the Az-XESPSN membranes exhibited higher proton conductivities (0.018–0.028 S cm −1 ) compared to those of the ESPSN membranes (0.0044–0.0053 S cm −1 ) and Nafion 212 (0.0061 S cm −1 ), particularly in conditions of elevated temperature (120 °C) and low relative humidity (35%). Such enhancements can be attributed to a synergistic effect of well-defined hydrophilic ionic clusters and triazole groups that function as proton carriers under anhydrous conditions. Furthermore, the Az-XESPSN membranes exhibited significantly enhanced single cell performance and long-term stability compared to those of ESPSN membranes.

Herein, we demonstrate thermally rearranged polybenzoxazole-co-imide (TR-PBOI) electrospun nanocomposite membranes for membrane distillation and membrane crystallization applications. We seek to demonstrate that a synergistic combination of TR polymers, porous nanofibrous membranes, and particle coating improves the long-term stability while maintaining high porosity and water flux. The fabricated membranes exhibit an excellent water flux (80 kg m−2 h−1) and NaCl rejection (>99.99%) with steady performance over more than 186 hours. In addition, for the first time, controlling the heterogeneous nucleation phenomena in membrane crystallization was clearly demonstrated using TR membrane morphology.

Highly permeable, thermally rearranged polymer membranes based on bismaleimide derivatives that exhibit excellent CO2 permeability up to 5440 Barrer with a high BET surface area (1130 m2 g−1) are reported for the first time. In addition, the membranes can be easily used to form semi-interpenetrating networks with other polymers endowing them with superior gas transport properties.

Thermally rearranged poly(benzoxazole-co-imide) (TR-PBOI) hollow fiber membranes were fabricated from a hydroxyl polyimide-co-polyimide (HD5) precursor containing equal molar amounts of non-TR-able DAM and TR-able HAB. A wide variety of spinning conditions were optimized in order to improve the gas permeation properties. A high bore flow rate (DI water) led to lowered gas permeation properties due to the generation of a dense, thick skin layer. The shear rate contributed significantly to manipulate the polymer chain packing density during spinning, therefore, CO2 permeance was critically enhanced in low shear rate. The addition of co-solvent (propionic acid) and pore forming agent (PEG 200) was shown to improve the gas permeation properties. The TR-PBOI hollow fiber membrane fabricated under optimal spinning conditions exhibited an excellent CO2 permeance of 560 GPU and CO2/N2 ideal selectivity of 16.8. A TR-PBOI hollow fiber module was successfully fabricated with an effective area of 106 cm2 for the mixed-gas permeation tests with a ternary gas mixture containing 14% CO2, 6% O2, and 80% N2. The results showed a permeate CO2 concentration around 50% and CO2 permeance of 400 GPU at a pressure ratio of 10.

Ortho -hydroxypolyimides (HPIs) undergo thermal rearrangement processes in a solid state at high temperatures to produce thermally rearranged polybenzoxazoles (TR-PBOs), which are promising materials for gas separation membranes due to their exceptional permeability-selectivity performance. The strong dependence between the structure of HPIs and the final properties of the TR-PBOs and the high cost of the HPI precursors are considered excellent reasons for their continued study. In this work, a set of low-cost HPIs were synthetized via the reaction of 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) with 2,4-diaminophenol dihydrochloride (DAP-Cl) and 4,6-diaminoresorcinol dihydrochloride (DAR-Cl). The polyimide made from 6FDA and m -phenylene diamine (MPD) was also obtained for comparison purposes. The polyimide precursors and the corresponding TR-PBOs, which were tested as films, were thoroughly characterized. The glass transition temperature of these precursor polyimides was shown to be a function of the number of hydroxyl groups such that the lowest value corresponded to the polyimide from MPD and the highest value corresponded to that derived from DAR. The conversion rate of HPIs to PBO at different processing temperatures was determined, and the highest conversion rate matched the DAP derived polyimide. With respect to their gas separation properties after thermal treatment at 450 °C, these HPIs gave rise to TR-PBOs with very high permeability and satisfactory permselectivity values for several gas pairs.

In this study, crosslinked polymer electrolyte membranes for polymer electrolyte membrane fuel cell (PEMFC) applications are prepared using electron beam irradiation with a mixture of sulfonated poly(ether ether ketone) (SPEEK), poly(vinylidene fluoride) (PVDF), and triallyl isocyanurate (TAIC) at a dose of 300 kGy. The gel-fraction of the irradiated SPEEK/PVDF/TAIC (95/4.5/0.5) membrane is 87% while the unirradiated membrane completely dissolves in DMAc solvent. In addition, the water uptake of the irradiated membrane is 221% at 70 °C while that of the unirradiated membrane completely dissolves in water at above 70 °C. The ion exchange capacity and proton conductivity of the crosslinked membrane are 1.57 meq g−1, and 4.0 × 10−2 S cm−1 (at 80 °C and RH 90%), respectively. Furthermore, a morphology study of the membranes is conducted using differential scanning calorimetry and X-ray diffractometry. The cell performance study with the crosslinked membrane demonstrates that the maximum power density is 518 mW cm−2 at 1036 mA cm−2 and the maximum current density at applied voltage of 0.4 V is 1190 mA cm−2.

Two series of sulfonated polybenzothiazoles containing naphthalene, derived from either 2,2-bis(4-carboxyphenyl) hexafluoropropane (6FA) or 2,6-naphthalene dicarboxylic acid (NA) were synthesized by polycondensation with non-sulfonated monomer 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT) and sulfonated monomer 4,8-disulfonyl-2,6-naphthalene dicarboxylic acid (DSNA). The sPBT-6FA series polymers containing DSNA were soluble in polar aprotic solvents such as dimethyl sulfoxide or 1-methyl-2-pyrrolidinone, whereas sPBT-NA65 with NA was not soluble in common polar aprotic solvents. Therefore, the incorporation of both the naphthalene and flexible hexafluoroisopropylidene units enhanced the solubility of the sPBT polymer series. The polymers were evaluated as proton exchange membranes and exhibited excellent dimensional stability, high thermal and oxidative stabilities, good mechanical properties, and high proton conductivities. The proton conductivities of sPBT-6FA65 were 0.25 S cm −1 at 80 °C in water and 0.018 S cm −1 at 120 °C under 35% RH.

Insufficient mechanical properties are one of the major obstacles for the commercialization of ultrahigh permeability thermally rearranged (TR) membranes in large-scale gas separation applications. The incorporation of preformed benzoxazole/benzimidazole units into o-hydroxy copolyimide precursors, which themselves subsequently thermally rearrange to form additional benzoxazole units, were prepared for the first time. Using commercially available monomers, mechanically tough membranes prepared from random and block TR poly(benzoxazole-co-imide) copolymers (TR-PBOI) were investigated for gas separation. The effects of the chemical structures, copolymerization modes, and thermal holding time of o-hydroxy copolyimides on the molecular packing and properties, including gas transport, for the resulting TR-PBOI membranes have been examined in detail. After treatment at 400 °C, tough TR-PBOI membranes exhibited tensile strengths of 71.4–113.9 MPa and elongation at break of 5.1–16.1%. Moreover, they presented hig...

End-group crosslinkable sulfonated poly(arylene ether sulfone) copolymer (ESPAES) and imidazolium poly(arylene ether sulfone) copolymer (IPAES) are synthesized as a proton exchange membrane and ionic crosslinker, respectively. A novel dually cross-linked membrane (DCM) based on ESPAES is similar to an inter-penetrating network and is prepared via blending IPAES and thermal treatment for direct methanol fuel cell (DMFC) applications. The synergistic effects of end-group crosslinking and ionic crosslinking improve chemical and thermal stability and mechanical properties. In addition, the DMFC performance of the DCM outperforms that of the end-group cross-linked SPAES and Nafion ® 212 due to its excellent fuel barrier property in spite of relatively low proton conductivity, which is derived from the content of the non-proton conducting IPAES copolymer. Consequently, the DCM has great potential as an electrolyte membrane for DMFC applications.

The incorporation of small amounts of 3,5-diaminobenzoic acid (DABA) comonomer (usually 5–20 mol %) into an ortho-hydroxypolyimide (HPI) precursor constitutes a new methodology to easily improve the gas transport performance of thermally rearranged (TR) polymer membranes. Thermogravimetric analysis (TGA) profiles of HPI with DABA copolyimides (HPID) suggests that there is an overlap between the temperature ranges of two processes: the degradation of DABA carboxyl groups and the actual thermal rearrangement process. During thermal treatment at 450 °C, carboxyl pendant groups in DABA degrade while a more rigid biphenyl cross-linked structure is formed either following or at the same time as the rearrangement of imide to benzoxazole. Mixed-gas CO2/CH4 (1:1) experiments proved this new series of cross-linked TR poly(benzoxazole-co-imide) (XTR-PBOI) membranes as superior materials for CO2/CH4 separation applications, with enhanced permeability and selectivity, as well as high resistance to plasticization up to...

The gas sorption behavior of polyimides (PIs) incorporating Tro¨ger׳s base (TB) units was investigated for five representative small gases (H2, N2, O2, CH4, and CO2) by barometric pressure decay methods at 35 °C. Methanol treatment of the PI-TB membranes increased the sorption, diffusion, and permeation of the small gas molecules because of increased interactions between the polymer and gas molecules as well as an increase of the FFV due to dilation of the polymers. Two different solubility determination methods, pressure-decay based and time-lag based methods, were introduced and compared. The gas solubilities of relatively condensable gases such as CO2 and CH4 showed good agreement between the two solubility measurements. Two different dianhydrides (6FDA and BTDA) in the PI-TBs were also introduced to determine their structural contributions to the gas sorption and transport properties. The two PI-TBs showed similar behavior in Henry׳s mode sorption. However, their Langmuir mode sorption demonstrated distinctive behavior, resulting in different gas transport phenomena. Methanol-treated PI-TB membranes exhibited plasticization resistance for CO2 permeation under high CO2 content feed in CO2/CH4 mixture. Incorporating TB units in the PI backbones achieved comparable microporosity and gas permeability results especially for CO2 separation in highly permeable polymer membranes.

Microporous polymers are a class of microporous materials with high free volume elements and large surface areas. Microporous polymers have received much attention for various applications in gas separation, gas storage, and for clean energy resources due to their easy processability for mass production, as well as microporosity for high performance. This review describes recent research trends of microporous polymers in various energy related applications, especially for gas separations and gas storages. The new classes of microporous polymers, so-called thermally rearranged (TR) polymers and polymers of intrinsic microporosity (PIMs), have been developed by enhancing polymer rigidity to improve microporosity with sufficient free volume sizes. Their rigidity improves separation performance and efficiency with extraordinary gas permeability. Moreover, their solubility in organic solvents allows them to have potential use in large-scale industrial applications.

Thermally rearranged polybenzoxazoles (TR-PBO) are some of the most promising materials for gas separation because of their microporous and bimodal cavities that offer high gas transport performance. However, the brittleness of fully converted TR-PBO membranes has impeded their widespread industrial implementation. In this study, we prepared novel, thermally rearranged poly(benzoxazole-co-imide) membranes (TR-PBOI) with improved mechanical strength and good gas separation performance. These membranes are based on two commercially available TR-able diamines and two non-TR-able diamines with various compositions and different polymer rigidities. TR-PBOI membranes with the appropriate ratio of PBO and PI displayed a high fractional free volume and therefore exceptional gas separation properties (CO2 permeability over 300 barrer and CO2/N2 ideal selectivity above 20); both these values were higher than those of the corresponding original TR-PBO membranes. Furthermore, a substantial improvement in the mechanic...

The sub-nano-sized microcavities in microporous thermally rearranged (TR) polymers can be tuned by varying the conditions of thermal rearrangement. Relatively small cavities were formed by thermal rearrangement of poly(o-hydroxylamide) (PHA) precursors compared to the cavities formed by that of polyimide precursors. TR polymers derived from PHAs, so-called TR-β-polymers, are known to exhibit a well-tuned cavity structure that can be used for H 2 /CO 2 separation. According to a solution-diffusion model, both the permeability and selectivity for H 2 /CO 2 separation were improved at elevated temperatures due to a significant increase in H 2 diffusion and a decrease in CO 2 sorption. In this study, gas solubility and permeability of five representative small gas molecules (H 2 , N 2 , O 2 , CH 4 , and CO 2 ) through TR-β-polymer membranes were characterized between 20 °C and 65 °C for gas solubility measurement and between 35 °C and 300 °C for gas permeability measurement. These measurements allowed for the calculation of thermodynamic factors such as the activation energy and heat of sorption.

This study presents a facile fabrication method for monodisperse poly(methacrylic acid/ethylene glycol dimethacrylate)/Fe3O4 [poly(MAA/EGDMA)/Fe3O4] composite microcapsules with magnetic properties and hollow structures for use as a targeted drug delivery system. In aqueous solution, the iron ions diffuse into the negatively-charged spherical polymer particles by electrostatic attraction. Since the obtained polymer–metal complexes decrease the repulsive force between the negatively-charged carboxyl groups of the polymer chains, the chelating parts of the polymer particles lose their hydrophilic properties and become relatively hydrophobic. As the number of iron ions continues to increase in the polymer particles, an internal cavity begins to be formed by interaction between the hydrophobic domains and the inner polymer chains. After the reducing agent is added into the synthetic system, Fe3O4 nanoparticles formed in the shells of the polymer particles retain the hollow structure. Confocal laser scanning microscopy and zeta potential measurements are employed to confirm the formation of the hollow structure during the diffusion of the various metal ions into the polymer gel. The magnetic properties of the poly(MAA/EGDMA)/Fe3O4 composite microcapsules synthesized under diverse experimental conditions are characterized by a vibrating sample magnetometer. The controlled release behavior of the model drug doxorubicin hydrochloride from the polymer–metal hollow composite microcapsules is investigated under different pH conditions.

A facile approach to synthesize poly(benzoxazole-co-imide)s without thermal rearrangement at high temperature is proposed. Poly(benzoxazole-co-imide)s with improved mechanical and solution-processable properties were prepared through polycondensation of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) with three synthesized novel benzoxazole-containing diamines and a commercial diamine. These poly(benzoxazole-co-imide)s had high tensile strengths of 110.3–122.0 MPa and good elongation at break of 11.9–26.3%, good thermal stability and high glass transition temperatures (Tgs) of up 306 °C. The effect of chain isomerism on molecular packing and physical and gas transport properties of the poly(benzoxazole-co-imide)s was investigated. The para-connecting isomers exhibited higher molecular weights (Mws), better mechanical properties, higher Tgs, higher chain packing order and better overall performance for CO2/CH4 and CO2/N2 separations as compared to the corresponding meta-connecting ones. This st...

In this study, crosslinked sulfonated poly(ether ether ketone) (SPEEK) membranes were prepared using an EB-irradiation crosslinking method with various contents of a crosslinker mixture (1,4-butanediol divinyl ether (BDVE)/triallyl isocyanurate (TAIC), 9/1 wt. ratio) and applied as a proton exchange membrane (PEM) for fuel cell application. It was found that the degree of crosslinking of the EB-crosslinked SPEEK membranes was increased with an increase in the BDVE/TAIC crosslinker content from gel fraction results. The chemical stability was also found to be improved with an increase in the content of the crosslinker mixture. The water uptake, IEC, and proton conductivity of the crosslinked membrane was found to be decreased with an increase in the BDVE/TAIC crosslinker content. The DMA and SAXS data indicated that the EB-crosslinked SPEEK membrane have well-developed ionic aggregation in the cluster regions. In addition, the current density of the crosslinked membranes was measured to be higher than 1198 mA/cm 2 at a 0.4 voltage (V) under fully hydrated conditions at 80 °C with a 1.5 bar backpressure from a MEA cell performance test.

Two series of random sulfonated poly(benzothiazole-co-benzimidazole) polymers (sPBT-BI) with 70% and 60% degree of sulfonation were evaluated as proton exchange membranes. sPBT was also prepared for a comparative study. The mechanical properties of sPBT-BI were greatly enhanced by incorporation of benzimidazole (BI); sPBT-BI70-10 showed a tensile strength of 125 MPa and elongation at break of 38.9%, an increase of 56.5% and 145%, respectively, compared with sPBT. The solubility, dimensional stability, thermal properties, and oxidative stability of sPBT-BI were also improved. The ionic clusters of sPBT-BI membranes in both AFM phase images and TEM images became narrower with increasing amounts of BI while containing the same molar amount of sulfonic acid groups. This resulted in lower dimensional swelling and higher mechanical strength, but the proton conductivity decreased. However, high proton conductivity was achieved by incorporating an appropriate content of BI. PEMFC H2/air single cell performances a...

Inorganic–organic composite membranes are fabricated using zirconium acetylacetonate nanoparticles and biphenol-based sulfonated poly(arylene ether sulfone) as an inorganic, proton conducting nanomaterial and a polymer matrix, respectively. An amphiphilic surfactant (Pluronic®) induces distribution of the inorganic nanoparticles over the entire polymer membrane. The composite membranes are thermally stable up to 200 °C. Zirconium acetylacetonate improves inter-chain interactions and the robustness of polymer membranes resulting in excellent membrane mechanical properties. In addition, composite membranes show outstanding proton conductivity compared to that of the pristine membrane at medium temperatures (80–120 °C) and low relative humidity (

Polyimides with intrinsic microporosity were readily prepared by introducing Tröger’s base (TB) into the polymer backbone via polymerization between imide-containing diamines and dimethoxymethane (DMM). Two imide-containing diamines were prepared by reaction of 2,5-dimethyl-1,4-phenylenediamine (DPD) with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA). The resulting polyimides were readily soluble in common organic solvents, had good mechanical properties, with tensile strength in the range of 59–64 MPa and elongation at break of 5–17%, good thermal stability and extremely high glass transition temperatures (Tgs), up to 425 °C. The polyimides with incorporated TB units had high fractional free volume (FFV ≥ 0.215) resulting from poor chain-packing and exhibited significant microporosity and good gas transport properties. The novel polymer architecture in this study extends the development of polyimides with intrinsic microporosity for membrane-based gas separation.

End-group crosslinked sulfonated poly(arylene sulfide nitrile) (XESPSN) membranes are prepared to investigate the effect of crosslinking on the properties of sulfonated aromatic polymer membranes at elevated temperatures (>100 °C). The morphological transformation during annealing and crosslinking is confirmed by atomic force microscopy. The XESPSN membranes show outstanding thermal and mechanical properties compared to pristine and non-crosslinked ESPSN and Nafion ® up to 200 °C. In addition, the XESPSN membranes exhibit higher proton conductivities (0.011–0.023 S cm −1 ) than the as-prepared pristine ESPSN (0.004 S cm −1 ), particularly at elevated temperature (120 °C) and low relative humidity (35%) conditions due to its well-ordered hydrophilic morphology after crosslinking. Therefore, the XESPSN membranes demonstrate significantly improved maximum power densities (415–485 mW cm −2 ) compared to the ESPSN (281 mW cm −2 ) and Nafion ® (314 mW cm −2 ) membranes in single cell performance tests conducted at 120 °C and 35% relative humidity. Furthermore, the XESPSN membrane exhibits a much longer duration than the ESPSN membrane during fuel cell operation under a constant current load as a result of its improved mechanical and thermal stabilities.

Thermally rearranged polymer membranes exhibit extraordinary gas permeability based on a rigid polymer structure with a high free volume element. In this study, TR poly(benzoxazole-co-imide) membranes from 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), 3,3′-dihydroxyl-4-4′-diamino-biphenyl (HAB), 2,2′-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (bisAPAF), and 2,4,6-trimethyl-m-phenylenediamine (DAM) were prepared to improve their gas separation properties. Copolymer membranes of polyimides and TR polybenzoxazoles may be desirable to generate efficient gas transport properties as well as to process polymers into fiber or film forms. Gas permeability, diffusivity, and solubility of the precursor polyimide and TR poly(benzoxazole-co-imide) membranes were investigated to characterize gas transport properties for small gas molecules including H2, O2, N2, CH4, and CO2. Thermal rearrangement process resulted in an increase in polymer free volume, which improved the diffusion and sorption coefficients.

The molecular simulation technique was adopted to investigate the structure and transport performance of thermally rearranged poly(benzoxazole-co-imide) membranes. A molecular dynamics (MD) technique was used to construct three models: a poly-benzoxazole (PBO) membrane with high free volume; a polyimide (PI) membrane with dense structure; and their co-polymer, PBO-PI membrane. The MD simulation was performed to characterize the membrane models to understand how the very rigid benzoxazole segments affect the micro-structure, free volume, cavity size, and gas diffusion of the membrane models. A Monte Carlo method was adopted to investigate the gas sorption behaviors in the three types of membranes. The torsional angle and wide-angle X-ray diffraction analyses suggest that the benzoxazole segments stiffened the polymeric chains, leading to the formation of a looser structure. In free-volume and cavity-size studies, the PBO membrane exhibited the highest free volume and largest cavity size, which can be attributed to the presence of the benzoxazole structure constructed by thermal rearrangement. The enlarged free volume in the membranes with benzoxazole segments provided more space for gas sorption and diffusion, which effectively enhanced the gas permeability. In addition, increasing the benzoxazole segments in the membrane structure enhances the gas sorption in accordance with Henry's law, as the PBO membrane provides more inter-polymeric chain space and allows for the larger free volume elements. Fabrication of the poly(benzoxazole-co-imide) membrane with an appropriate PBO/PI composition would help optimize the gas permeability and selectivity in the gas separation process. The results from the simulation agree with the experimental data, indicating that the molecular simulation technique is a useful method in the field of materials design and development for the membrane separation process.

Thermally rearranged poly(benzoxazole-co-amide) (TR-PBOA) copolymer membranes were prepared by treating poly( o -hydroxyamide-co-amide) (PHAA) precursors by in-situ thermal cyclization reaction for the H 2 separation at high temperature. The physical properties, membrane processability and gas permeation property can be controlled by varying the ratio of diamine compounds. The rigid biphenyl moiety in the copolymer membranes increases gas selectivity whereas the flexible ether moiety improves membrane processability as well as gas permeability. Moreover, thermal rearrangement process affects the gas separation properties of TR copolymer membranes. TR polymer membranes derived from polyhydroxyamides (PHAs) demonstrated high H 2 permeability, but low H 2 /CO 2 selectivity. However, TR-PBOA copolymer membranes improved H 2 /CO 2 selectivity. Both permeability and selectivity of H 2 over CO 2 increased due to the high activation energy for H 2 permeation through the copolymer membranes and can be explained by thermodynamic theory with temperature. The highest performance was 26.8 Barrer of H 2 permeability and 8.0 of H 2 /CO 2 selectivity measured at 210 °C.

A novel strategy to tune the cavity size and free volume of thermally rearranged polybenzoxazole (TR-PBO) copolymer membranes by transesterification cross-linking reaction of o-hydroxy polyimide precursors with 1,4-butylene glycol in the solid state is demonstrated in this study. During the thermal rearrangement (TR) process at high temperatures, loose diester interchain cross-linkers are prone to degrade while formation of a much more rigid cross-linked structure occurs following or alongside the imide-to-benzoxazole rearrangement. As a result, a synergistic effect of high permeability and high selectivity appeared to be created in one step, and the newly synthesized cross-linked TR-PBO membranes exhibited outstanding gas separation performance, surpassing the so-called 2008 upper bound for CO2/CH4 separation.

We investigated the effects of the polymer chemical structure on the gas separation performances of thermally rearranged poly(benzoxazole-co-imide) (TR-PBO-co-I) membranes. Eight non-TR-able aromatic diamines, one TR-able hydroxyl diamine, and one dianhydride were utilized to synthesize precursors of TR-PBO-co-I. For comparison, a thermally rearranged (TR) polybenzoxazole (PBO) homopolymer precursor was also synthesized from the same type of dianhydride and hydroxy diamine. All precursors were fabricated into membranes and thermally treated in the solid state to produce TR-PBO-co-I/TR-PBO membranes. It was confirmed that the non-polar bulky side groups in the diamines disrupted polymer chain packing and increased the fractional free volume (FFV) most effectively, resulting in increased gas permeabilities. A significant increase of the polymer rotational mobility imposed by the non-TR-able diamines promoted higher chain rotational motion which resulted in higher gas permeabilities. The percentage of conversion, which should affect the gas permeabilities, was very similar in all TR-PBO-co-I/TR-PBO membranes. Therefore, it was not a main factor in influencing the gas permeability of the TR-PBO-co-I/TR-PBO membranes. The gas selectivities of small gas molecules were improved if the non-TR-able diamines had a somewhat flat and rigid structure. The gas selectivities were also found to be much higher in the TR-PBO-co-I copolymer membranes compared to the TR-PBO homopolymer membrane.

Tributyl O-acetyl citrate, also called acetyl tributyl citrate (ATBC), a new, environmental friendly diluent was introduced to prepare flat sheet and hollow fiber poly(vinylidene fluoride) (PVDF) membranes via thermally induced phase separation (TIPS). A phase diagram of PVDF/diluent is presented and the effect of different parameters such as polymer concentration, quenching temperature, air gap, and bore fluid temperature on the morphologies, properties, and water permeability of the PVDF membranes were investigated. The prepared PVDF membranes exhibited a form, and the mechanical properties and pure water flux are promising. (C) 2013 Elsevier B.V. All rights reserved.

Ordered morphologies in disulfonated poly(arylene sulfide sulfone nitrile) (SPSN) copolymers were generated via thermal annealing followed by multiblock copolymer synthesis. While SPSN random copolymers (R-SPSN) showed featureless morphologies, the SPSN multiblock copolymers (B-SPSN) exhibited cocontinuous lamellar morphologies with a center-to-center interdomain size of up to 40 nm. In spite of the well-ordered, interconnected hydrophilic domains, the water self-diffusion coefficient (e.g., D = (0.7–2.0) × 10–10 m2 s–1) and proton conductivity (e.g., σ = 0.16–0.20 S cm–1 in deionized water at 30 °C) through B-SPSN were lower than those of the corresponding R-SPSN (e.g., D = (3.5–3.9) × 10–10 m2 s–1 and σ = 0.21 S cm–1) due to the relatively lower water uptake of the B-SPSN after thermal annealing. The reduced water uptake of B-SPSN was beneficial to reduction of peroxide degradation rate. Thermal annealing produced significant gains in morphological ordering and finer control over desired membrane proper...

The gas solubility of thermally rearranged polybenzoxazole (TR-PBO) membranes and precursor polymer membranes was determined for five representative small gas molecules, H 2 , N 2 , O 2 , CH 4 , and CO 2 , at 35 °C and pressures up to 23 atm. Precursor membranes that thermally rearranged to TR-PBO were prepared from 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (bisAPAF) and 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA) using three different imidization methods. Sorption isotherms of TR-PBO followed the dual-mode sorption model, which is regarded as a typical model for glassy polymers. The Henry's law coefficient ( k D ), Langmuir affinity parameter ( b ), and Langmuir capacity parameter ( C′ H ) were determined using the dual-mode sorption equation. During the thermal rearrangement process, excess free volume in the polymer membrane matrix increased and improved molecular transport was observed. A similar trend of increasing solubility was observed during the thermal rearrangement process. The gas permeability and diffusivity of TR-PBO membranes were also studied using the solution–diffusion model.

We demonstrate that small and narrow hydrophilic conducting domain morphology in sulfonated aromatic membranes leads to much better fuel cell performance at medium temperature and low humidity conditions than those with larger hydrophilic domains. A comparison of three types of sulfonated poly(arylene ether sulfone)s (SPAES) with random, block, and graft architecture indicates that small hydrophilic domain sizes (100 °C) fuel cell applications. The graft copolymer outperformed both a random copolymer and multiblock copolymer at 120 °C and 35% RH fuel cell operating conditions due to capillary condensation of water within the 3–5 nm hydrophilic domains. Keywords: Fuel cell, Polymer electrolyte membrane, Medium-temperature, Sulfonated poly(arylene ether sulfone), Morphology

Novel spirobisindane-containing thermally rearranged (TR) benzoxazole(spiroTR-PBO) membranes were prepared by thermal treatment of four newly synthesized spirobisindane-containing hydroxyl-polyimides (spiroHPIs). Transport properties of spirobisindane-containing polymers were investigated along with fractional free volume and density measurements, as well as molecular simulation analysis. The resulting spiroTR-PBOs exhibited high free volumes and superior mechanical properties in terms of elongation and tensile strength, and these findings were supported by molecular dynamic simulations. SpiroTR-PBO membranes containing hexafluoroisopropylidene moiety in the polymer backbone showed a six-fold increase in CO2 permeability, compared to that of the spiroHPI precursor. SpiroTR-PBO membranes showed strong potential to be applied in carbon capture and separation of gases because of their high gas permeability coupled with robust mechanical properties.

Membrane technology for gas separation applications was commercialized about three decades ago for natural gas upgrading and nitrogen blanketing purposes, in particular, using a limited number of polymer materials such as polysulfone, cellulose acetate, and polyimide. There are still many opportunities for the development of new polymer membrane materials for gas separation applications as the separation performance of existing membrane materials should be improved. In this review, we introduce the research progress on the recent development of high performance gas separation membranes for CO2 separation applications.

Sulfonated poly(arylene sulfide sulfone nitrile)s (SN) were synthesized to investigate the effects of naphthalene units in the polymer backbone on membrane properties. The small and planar naphthalene in the main chain induced semi-crystallinity in the polymer, as confirmed by molecular simulations and wide angle X-ray diffraction patters. The semi-crystalline SN polymer membranes exhibited excellent chemical and mechanical properties, better than those of their phenylene counterpart (SP). In particular, the water uptake and swelling ration of the SN membranes were much lower than those of the SP membranes. Furthermore, the SN membranes exhibited a greatly reduced methanol permeability (9-17 x 10(-8) cm(sq) s(-1)) compared to Nafion 212(330 x 10(-8) cm(sq) s(-1)) at 30 degrees Celsius in 10 M methanol. Moreover, sulfide- and naphthalene-based chemical structure and semi-crystalline nature of hte SN membranes enhanced their DMFC single cell performance and long-term stability during fuel cell operation.

A fundamental understanding of polymer microstructure is important in order to design novel polymer electrolyte membranes (PEMs) with excellent electrochemical performance and stabilities. Hydrocarbon-based polymers have distinct microstructure according to their chemical structure. The ionic clusters and/or channels play a critical role in PEMs, affecting ion conductivity and water transport, especially at medium temperature and low relative humidity (RH). In addition, physical properties such as water uptake and dimensional swelling behavior depend strongly on polymer morphology. Over the past few decades, much research has focused on the synthetic development and microstructural characterization of hydrocarbon-based PEM materials. Furthermore, blends, composites, pressing, shear field, electrical field, surface modification, and cross-linking have also been shown to be effective approaches to obtain/maintain well-defined PEM microstructure. This review summarizes recent work on developments in advanced PEMs with various chemical structures and architecture and the resulting polymer microstructures and morphologies that arise for potential application in fuel cell, lithium ion battery, redox flow battery, actuators, and electrodialysis.

Thermally rearranged (TR) polymers are microporous with high fractional free volume and narrow cavity size distribution. As a result, they exhibit excellent gas permeability and selectivity, exceeding the Robeson upper bound. This article provides a detailed discussion on the influence of TR polymer types on free volume topology. General principles are offered for TR polymer design, including the choice of monomers and synthesis routes, and their relationships with the polymer free volume topology and eventually the gas permeation properties. Other aspects including characterization techniques and industrial-scale implementation and applications are also provided.

In this study, sulfonated poly(ether ether ketone) (SPEEK) membranes with a crosslinked structure were prepared by the EB-irradiation crosslinking of a mixture of SPEEK and crosslinkers with various irradiation doses. The crosslinked membranes were utilized as proton exchange membranes (PEM) for fuel cell application. The pure SPEEK and crosslinked SPEEK (CSPEEK) membranes were characterized by using 1 H and 13 C NMR spectroscopy, gel fraction, and a dynamic mechanical analysis (DMA). It was observed that the sulfonic acid groups were introduced exclusively to the hydroquinone segments after the treatment of PEEK with concentrated sulfonic acid and the degree of sulfonation was measured to be 0.69 from the NMR peak integration. The gel fraction study of EB-treated SPEEK membranes indicates that the EB-irradiation doses have a direct effect on the degree of crosslinking. The DMA and SAXS results showed that the CSPEEK membranes have well-developed ionic aggregation in the cluster region. These results indicate that the ionic aggregations of the SPEEK membranes are not largely affected by irradiation. The water uptake of the CSPEEK membranes was found to be lower than 30% at room temperature, and the proton conductivity to be higher than 10 −2 S/cm. Finally, the current densities of the CSPEEK membranes irradiated with 50, 100, and 200 kGy, were measured to be 221, 482, and 522 mW/cm 2 , respectively, at a violated of 0.4 V and at 80 °C. The overall findings suggest that the CSPEEK membranes prepared by EB irradiation are expected to be useful for PEMFC since they exhibit high dimensional stability as well as good cell performance.

A microbial fuel cell (MFC) is a bio-electrochemical system that drives a current by mimicking bacterial interactions found in nature. Usually, MFCs use Nafion as a PEM to separate the electrodes while permitting protons transfer between the anode and cathode. However, Nafion is expensive and accounts for a large percentage of the costs in MFC configuration. Here, we show MFCs using hydrocarbon-based PEM, disulfonated poly (arylene ether sulfone) (BPSH), which is considered as one of alternative PEM, and relatively inexpensive as compared with Nafion. BPSH membranes exhibit a comparable performance to Nafion 212. Especially, BPSH 40 and 60 (mole %) have higher proton conductivity than Nafion 212. In a two-chamber system, MFC with BPSH 40 shows higher voltage than that with Nafion 212. MFCs with BPSH 20 and 30 show lower voltage decline than other PEMs. In a single-chamber system, a voltage of MFC with BPSH 40 shows about 30% higher (17 mV) than that with Nafion 212 (13 mV) with internal resistance of 10 Ω. In addition, The MFC with BPSH 40 produced about 10% higher maximum power density (126 mW m−2) than that with Nafion 212 (111 mW m−2).