• Membrane Journal
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• v.25 no.6
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• pp.515-523
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• 2015

While commercial polystyrene-based ion exchange membranes have simple manufacturing processes, they also possess poor durability due to their brittleness. Poly(ethylene glycol)methyl ether methacrylate with hydrophilic side chains of poly(ethylene glycol) was used as a co-monomer to make the membranes have improved flexibility. Hydrophilicity/hydrophobicity of the anion exchange membranes were able to be adjusted by varying the chain lengths of the poly(ethylene glycol). For the preparation of the anion exchange membranes, a porous PE substrate was immersed into monomer solutions and thermally polymerized. The prepared membranes were subsequently reacted with trimethylamine to produce anion exchange functional groups, Quaternary ammonium salts. The prepared pore-filled anion exchange membranes were evaluated in terms of ion exchange capacity, electric resistance, elongation at break and water uptake.

• Membrane Journal
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• v.33 no.2
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• pp.77-86
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• 2023

In this study, pore-filled ion exchange membranes with low membrane resistance and high hydroxide ion conductivity was developed. To improve alkali durability, a porous substrate made of polytetrafluoroethylene was used, and a copolymer was prepared using monomers 2-(dimethyl amino) ethyl methacrylate (DMAEMA) and vinyl benzyl chloride (VBC) for pores. divinyl benzene (DVB) was used as the cross-linker, and ion exchange membranes were prepared for each cross-linking agent content to study the effect of the cross-linker content on DMAEMA-DVB and VBC-DMAEMA-DVB copolymers. As a result, chemical stability is improved by using a PTFE material substrate, and productivity can be increased by enabling fast photo polymerization at a low temperature by using a low-pressure UV lamp. To confirm the physical and chemical stability of the ion exchange membrane required for an anion exchange membrane fuel cell, tensile strength, and alkali resistance tests were conducted. As a result, as the cross-linking degree increased, the tensile strength increased by approximately 40 MPa, and finally, through the silver conductivity and alkali resistance tests, it was confirmed that the alkaline stability increased as the cross-linking agent increased.

• Membrane Journal
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• v.34 no.1
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• pp.58-69
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• 2024

Reverse electrodialysis (RED) is an electro-membrane process employing ion-exchange membranes (IEMs) that can harvest electric energy from the concentration difference between seawater and river water. Multivalent ions contained in seawater and river water bind strongly to the fixed charge groups of the IEM, causing high resistance and reducing open-circuit voltage and power density through uphill transport. In this study, a pore-filled anion-exchange membrane (PFAEM) with excellent monovalent ion selectivity and electrochemical properties was fabricated and characterized for RED application. The monovalent ion selectivity of the prepared membrane was 3.65, which was superior to a commercial membrane (ASE, Astom Corp.) with a selectivity of 1.27 under the same conditions. Additionally, the prepared membrane showed excellent electrochemical properties, including low electrical resistance compared to ASE. As a result of evaluating RED performance under seawater of 0.459 M NaCl/0.0510 M Na₂SO₄ and river water of 0.0153 M NaCl/0.0017 M Na₂SO₄, the maximum power density of 1.80 W/m² was obtained by applying the prepared membrane, which is a 40.6% improved output performance compared to the ASE membrane.

• Membrane Journal
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• v.28 no.5
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• pp.307-319
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• 2018

Ion-exchange membrane (IEM) has fixed charge groups and is a separation membrane which is capable of selectively transporting ions of the opposite polarity. Recently, the interest in IEMs has been increasing as the importance of the desalination and energy conversion processes using them as the key components has increased. Since the IEMs determine the efficiency of the above process, it is necessary to improve the separation performance and durability of them and also to lower the expensive membrane price, which is a hindrance to the widening application of the IEM process. Therefore, it is urgent to develop high-performance and low-cost IEMs. Among various types of IEMs, pore-filled membranes prepared by filling ionomer into a porous polymer substrate are intermediate forms of homogeneous membranes and heterogeneous membranes. The production cost would be cheap like the case of heterogeneous membranes because of the use of inexpensive supports and the reduction of the amount used of raw materials, and at the same time, they exhibit excellent electrochemical characteristics close to homogeneous membranes. In this review, major research and development trends of pore-filled IEMs, which are attracting attention as high-performance and low-cost IEMs, have been summarized and reported according to the application fields.

• Membrane Journal
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• v.26 no.6
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• pp.432-448
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• 2016

In the last decade, various types of energy harvesting and conversion systems based on ion exchange membranes (IEMs) have been developed for eco-friendly power generation and energy-grid systems. In these membrane-based energy systems, high ion selectivity and conductivity properties of IEMs are critical parameters to improve efficiency of the systems such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, redox flow batteries, water electrodialysis for hydrogen production, and reverse electrodialysis. This article suggests variable approaches to overcome trade-off limitation of polymeric membrane ion transport properties by reviewing various types of composite ion-exchange membranes including novel inorganic-organic nanocomposite membrane, surface modified membranes, cross-linked and pore-filled membranes.

• Membrane Journal
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• v.25 no.2
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• pp.152-161
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• 2015

In this study, novel pore-filled anion-exchange membranes (PFAEMs) with low electrical resistance, high permselectivity, and low water-splitting flux property under a concentration polarization condition have been developed for the enhancement in the efficiency of electrochemical water treatment processes. The base membranes have been prepared by filling a copolymer containing quaternary ammonium groups with an excellent ion-exchange capability into a porous polyolefin substrate, showing a high performance superior to that of a commercial membrane. In addition, it was confirmed that the electrochemical membrane performances are preserved while the water-splitting flux is effectively controlled by coating an imidazolium polymer onto the surface of the base membrane. The prepared PFAEMs revealed remarkably low electrical resistances of about 1/6~1/8 compared to those of a commercial membrane, and simultaneously low water-splitting flux comparable with that of cation-exchange membranes under a concentration polarization condition.

• Membrane Journal
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• v.31 no.5
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• pp.351-362
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• 2021

All-vanadium redox flow battery (VRFB) is one of the promising high-capacity energy storage technologies. The ion-exchange membrane (IEM) is a key component influencing the charge-discharge performance and durability of VRFB. In this study, a pore-filled anion-exchange membrane (PFAEM) was fabricated by filling the pores of porous polytetrafluoroethylene (PTFE) support with excellent physical and chemical stability to compensate for the shortcomings of the existing hydrocarbon-based IEMs. The use of a thin porous PTFE support significantly lowered the electrical resistance, and the use of the PTFE support and the introduction of a fluorine moiety into the filling ionomer significantly improved the oxidation stability of the membrane. As a result of the evaluation of the charge-discharge performance, the higher the current efficiency was seen by increasing the fluorine content in the PFAEM, and the superior voltage and energy efficiencies were shown owing to the lower electrical resistance compared to the commercial membrane. In addition, it was confirmed that the use of a hydrophobic PTFE support is more preferable in terms of oxidation stability and charge-discharge performance.