• Membrane Journal
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• v.33 no.6
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• pp.279-304
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• 2023

Polybenzimidazole (PBI) based membranes have evolved in literature as a popular membrane material for various applications in the past two decades because of their high temperature thermal durability, strong mechanical and tensile properties, high glass transition temperature (T_g), ion conduction ability at elevated temperature (up to 200℃), oxidative or chemical durability along with robust network like structural rigidity, which make PBI membranes suitable for various potential applications in chemically challenging environments. Ion conducting PBI based membranes have been extensively utilized in high temperature proton exchange membrane fuel cells (HT-PEMFC). In addition, PBI based membranes have been vastly utilized for the development of gas separation membranes and organic solvent nanofiltration (OSN) membranes for their unique characteristics. This review will cover the recent progress and application of various types of flat sheet PBI based membranes for HT-PEMFC, gas separation and OSN application.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.420-426
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• 2017

Recently, solvent-resistant nanofiltration membranes have been studied for the separation of solvents or solutes using a molecular weight cut-off system of the polymer which is resistant to a specific solvent. Required conditions for these membranes must have are excellent physical properties and solvent resistance. Polybenzimidazole, which is known to be one of the most heat-resistant commercially available polymers, has an excellent inherent solvent resistance and it is even insoluble in stronger organic solvents when cross-linked. Therefore, in this study, the applicability of polybenzimidazole as a solvent resistant nanofiltration membrane was discussed. The membrane was fabricated using the non-solvent induced phase separation method and showed a suitable morphology as a nanofiltration membrane confirmed by field emission scanning electron microscopy. In addition, the permeance of the solvent in the presence or absence of cross-linking was investigated and the stability was also confirmed through long operation. The permeance test was carried out with five different solvents: water, ethanol, benzene, N, N-dimethylacetamide (DMAc) and n-methyl-2-pyrrolidone (NMP); each of the initial flux was $6500L/m^2h$ (water, 2 bar), $720L/m^2h$ (DMAc, 5 bar), $185L/m^2h$ (benzene, 5 bar), $132L/m^2h$ (NMP, 5 bar), $65L/m^2h$ (ethanol, 5 bar) and the pressure between 2 and 5 bar was applied depending on the type of membrane.

• Membrane Journal
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• v.32 no.6
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• pp.442-455
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• 2022

High-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) has been studied as an alternative to low-temperature PEMFC due to its fast activation of electrodes and high resistance to electrode poisoning by carbon monoxide. It is highly required to develop stable PEMs operating at high temperatures even doped by ion-conducting materials for the development of high-performance and durable HT-PEMFC systems. A number of studies have been conducted to develop polybenzimidazole (PBI)-based PEMs for applications in HT-PEMFC due to their high interaction with doped ion-conducting materials and outstanding thermomechanical stability under high-temperature operation. This review focused on the development of PBI-based PEMs showing high performance and durability. Firstly, the characteristic behavior of PBI-based PEMs doped with various ion-conducting materials including phosphoric acid was systematically investigated. And then, a comparison of the physicochemical properties of the PEMs according to the different membrane manufacturing processes was conducted. Secondly, the incorporation of porous polytetrafluoroethylene substrate and/or inorganic composites to PBI matrix to improve the membrane performances was studied. Finally, the construction of cross-linked structures into PBI-based PEM systems by polymer blending method was introduced to improve the PEM properties.

• Proceedings of the Korean Fiber Society Conference
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• 2000.04a
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• pp.257-260
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• 2000

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.128-135
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• 2019

In this study, the mesoporous $SiO_2$ (5, 10, or 15 wt%) was incorporated into the polybenzimidazole matrix in order to improve the proton conduction as well as physiochemical properties of composite membrane. The chemical structure of mesoporous $SiO_2$ and crystallinity of as-prepared membranes were analyzed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. The thermal stability of the pristine $X_1Y_9$ and composite membranes were evaluated by thermogravimetric analyzer (TGA). On other side, the physical and chemical properties of the pristine $X_1Y_9$ and composite membranes were also determined by acid uptake and oxidative stability tests, respectively. With the incorporation of 15 wt% $SiO_2$, the composite membrane exhibits the higher proton conductivity that may be applicable for non-humidified high temperature fuel cell applications.

• Membrane Journal
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• v.31 no.3
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• pp.228-240
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• 2021

The organic solvent robust polybenzimidazole (PBI) membranes were prepared as organic solvent nanofiltration (OSN) membrane for the recycling of alcoholic solvents using non-solvent induced phase separation with different dope solution concentration and coagulant composition of water/ethanol mixtures to control the membrane morphology and permeation performance. Investigation on crosslinking of polybenzimidazole indicated that the membrane crosslinked with dibromoxylene (DBX) had enough mechanical strength and solvent resistance to be applied as a OSN membranes. The crosslinked PBI membrane prepared by more than 20wt% dope concentration coagulated in water showed a rejection of > 90% to Congo Red (MW of 696.66 g/mol) while pure ethanol permeances was more than 22.5 LMH/bar at 5 bar. Investigation on coagulant composition indicated that ethanol permeance through crosslinked PBI OSN membrane increased with increasing of ethanol concentration in water/ethanol mixture coagulants.

• Korean Membrane Journal
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• v.9 no.1
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• pp.43-51
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• 2007

This paper describes the preparation and characterization of two kinds of fluorinated polybenzimidazole (PBI)s which can be potentially used for phosphoric acid-doped, high-temperature polymer electrolyte membrane fuel cells. Two kinds of perfluorocyclobutane (PFCB)-containing monomers were prepared via following synthetic steps; after fluoroalkylation of methyl 3-(hydroxy) benzoate and methyl 4-(hydroxy) benzoate with 1,2-dibromotetrafluoroethane and subsequent Zn-mediated dehalogenation, these compounds were cyclodimerized at $200^{\circ}C$ affording the ester-terminated monomers containing PFCB ether groups. The synthesized intermediates and monomers were characterized using FT-IR, $^1H-NMR,\;^{19}F-NMR$, and mass spectroscopy. The fluorinated PBIs were then successfully prepared through the solution polycondensation of the monomers and 3,3'-diaminobenzidine in polyphosphoric acid. Compared with traditional PBI, the glass transition temperatures of the fluorinated PBIs were obtained at $262^{\circ}C\;and\;269^{\circ}C$ which are lower than that of PBI and their initial degradation temperatures were still high over $400^{\circ}C$ under nitrogen. The fluorinated PBIs showed higher d-spacing values and improved solubility in several organic solvents as well as phosphoric acid, which confirmed they could be good candidates for the high temperature fuel cell membranes.

• Membrane Journal
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• v.20 no.3
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• pp.217-221
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• 2010

In order to overcome the drawback of proton exchange membrane fuel cells (PEMFCs), solid alkalime membrane fuel cells (SAMFCs) have been studied. In this report, we synthesized new sulfonated polybenzimidazole derivatives for SAMFCs. The polyimidazole derivatives were doped by KOH, and base-doped polybenzimidazoles showed high hydroxy ion conductivity and excellent mechanical properties. Especially, sPBI-co-PBI (75 : 25 for molar ratio of sulfonated and non-sulfonated moiety) showed good possibility for the anion exchange membrane. It has $2.98{\times}10^{-2}\;S/cm$ at $90^{\circ}C$ under 100% relative humidity.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.4
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• pp.439-445
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• 2007

Proton exchange membrane Fuel Cells(PEMFCs) have been spotlighted because of their broad potential application for potable electrical devices, automobiles and residential usages. However, their utilization is limited to low temperature operation due to the electrolyte dehydration at high temperature. High temperature PEMFC operation offers high CO tolerance and easy water management. This review presents development of high temperature($120{\sim}200^{\circ}C$) PEMFC. Especially, PEMFC which is based on acid-doped PBI membrane is discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.127-135
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• 2015

High-Temperautre Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) with phosphoric acid-doped polybenzimidazole (PBI) membrane has high power density because of high operating temperature from 100 to $200^{\circ}C$. In fuel cell stack, heat is generated by electrochemical reaction and high operating temperature makes a lot of heat. This heat is caouse of durability and performance decrease about stack. For these reasons, heat management is important in HT-PEMFC. So, we developed HT-PEMFC model and study heat flow in HT-PEMFC stack. In this study, we placed coolant plate number per cell number ratio as variable and analysed heat flow distribution in stack.