• Journal of the Korean Electrochemical Society
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• v.16 no.4
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• pp.204-210
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• 2013

Thin pore-filled cation and anion-exchange membranes (PFCEM and PFAEMs, $t_m=25-30{\mu}m$) were prepared using a porous polymeric substrate for efficient all-vanadium redox flow battery (VRB). The electrochemical and charge-discharge performances of the membranes have been systematically investigated and compared with those of commercially available ion-exchange membranes. The pore-filled membranes were shown to have higher permselectivity as well as lower electrical resistances than those of the commercial membranes. In addition, the VRBs employing the pore-filled membranes exhibited the respectable charge-discharge performances, showing the energy efficiencies (EE) of 82.4% and 84.9% for the PFCEM and PFAEM, respectively (cf. EE = 87.2% for Nafion 1135). The results demonstrated that the pore-filled ion-exchange membranes could be successfully used in VRBs as an efficient separator by replacing expensive Nafion membrane.

• Membrane Journal
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• v.27 no.5
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• pp.441-448
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• 2017

In this study, the effects of membrane characteristics on the power generation performance in reverse electrodialysis (RED) have been investigated with pore-filled ion-exchange membranes (PFIEMs) prepared by employing a porous polyethylene substrate and the mixtures of three cross-linking agents. As a result, it was confirmed through the correlation analyses that the cross-linking degree and free volume of the PFIEMs were effectively controlled by mixing the cross-linking agents having different molecular sizes, influencing complexly the electrochemical characteristics of the membranes and the power generation performance in RED. In particular, the pore-filled cation-exchange membranes at the optimum cross-linking conditions exhibited the power generation performance superior to that of the commercial membranes and the pore-filled anion-exchange membranes also showed the excellent performance close to that of the commercial membrane.

• Membrane Journal
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• v.26 no.1
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• pp.43-54
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• 2016

In this study, we have prepared engineering polymer-based ionomers and pore-filled ion-exchange membranes (PFIEMs) employing a porous polyethylene substrate and combined them to fabricate the ionomer-PFIEM composite membranes for the reverse electrodialysis (RED) application. Both the electrochemical properties comparable to those of the commercial ion-exchange membranes (AMX/CMX, Astom Corp., Japan) and the physical stability adaptable to the practical uses have been achieved by integrating the ionomers having a high ion conductivity and the PFIEMs with an excellent mechanical strength. The RED performances have been evaluated by employing the prepared ionomer-PFIEM composite membranes and therefore excellent power generation performances were shown as the levels of 86.4% and 104.8% for the anion-exchange membrane and cation-exchange membrane, respectively, compared with those of the commercial membranes.

• Membrane Journal
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• v.11 no.3
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• pp.109-115
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• 2001

Pore-filled ion-exchange membranes in which polypropylene(PP) microporous membrane was used as a nascent membrane were prepared by an in-situ cross-linking technique. Poly(vinylbenzyl chloride)(PVBCI) reacted with piperazine(PIP) or 1,4-diaminobicyclo[2,2,2]octane(DABCO) in a di-methylforamide(DMF) solution was filled in the pores of the microporous base membrane. After gellation the remaining chloromethyl groups were, then reacted with an amine such as trimethylamine to form positively charged, ammonium site. This will produce the pore-filled anion-exchange membrane. It was shown that this simple 2 step procedure gave dimensionally stable, pore-filled membranes in which the MG of polymer gel and degree of cross-linking could be easily controlled by the concentration of PVBCI and cross-linker in the starting DMF solution. Specially, high water permeability (7.8 kg/$m^2$hr, host membrane: PP3, MG: 73%, degree of cross-linking: 10%, crosslinker: PIP) at ultra low pressure(100 kPa) indicates the produced pore-filled membranes is usable as a water softening membrane.

• Membrane Journal
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• v.14 no.2
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• pp.108-116
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• 2004

In this study, the pore-filled ion-exchange membranes were prepared by using the asymmetric PVDF membrane as a nascent membrane. First, the solution of PVBCI having the chlorornethylate aryl ring of 80 percents and DABCO was made with the mixed solvent of THF and DU (8:2). These mixed solution was then, filled in the pores of PVDF membrane, and left for a day to complete the gelation. Finally the pore-filled anion-exchange membrane is obtained fallowed by the amination of the remaining chloromethyl groups with trimethylamine (TMA, 40 wt% in water) forming the positive ammonium ion sites. This 2 step procedure enabled us to produce the pore-filled membranes without change of size, and to control the properties of final membrane with various degree of cross-linking. The results of SEM and AFM showed the polyelectrolyte existed in the pores of nascent membrane as a certain configuration. From the investigation of the solvent affecting much to the permeability and rejection, it was found that the membranes using mixed solvent of THE and DMF (8:2) showed better performances than the membranes produced by THF only. The result of an investigation for the water permeability of the final membrane at low pressure (100 Kpa) showed a typical ultrafiltration membrane's permeability (8 ∼ 10 kg/$m^2$hr) and good values of rejection (55∼60 percent).

• Membrane Journal
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• v.32 no.5
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• pp.336-347
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• 2022

Reverse electrodialysis (RED) is one of the promising eco-friendly renewable energy technologies which can generate electricity from the concentration difference between seawater and freshwater by using ion-exchange membranes as a diaphragm. The ion-exchange membrane is a key component that determines the performance of RED, and must satisfy requirements such as low electrical resistance, high permselectivity, excellent durability, and low manufacturing cost. In this study, pore-filled anion-exchange membranes were fabricated using porous polymer substrates having various thicknesses and porosity, and the effects of ion-exchange polymer composition and membrane thickness on the power generation performance of RED were investigated. When the electrical resistance of the ion-exchange membrane is sufficiently low, it can be confirmed that the RED power generation performance is mainly influenced by the apparent permselectivity of the membrane. In addition, it was confirmed that the apparent permselectivity of the membranes can be improved through IEC, crosslinking degree, membrane thickness, surface modification, etc., and the optimum condition must be found in consideration of the trade-off relationship with electrical resistance.

• Membrane Journal
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• v.27 no.5
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• pp.406-414
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• 2017

In this study, we have developed pore-filled ion-exchange membranes (PFIEMs) filled with ionomer in a thin polyethylene porous film (thickness = $25{\mu}m$) and investigated the charge-discharge characteristics of the all vanadium redox flow battery (VRFB) employing them. Especially, the degree of crosslinking and free volume of the PFIEMs were appropriately controlled to produce ion-exchange membranes exhibiting both the low membrane resistance and low vanadium permeability by mixing crosslinking agents having different molecular size. As a result, the prepared PFIEMs exhibited excellent electrochemical properties which are comparable to those of the commercial membranes. Also, it was confirmed through the experiments of vanadium ion permeability and VRFB performance evaluation that the PFIEMs showed low vanadium ion permeability and high charge-discharge efficiency in comparison with the commercial membrane despite their thin film thickness.

• 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.30 no.1
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• pp.21-29
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• 2020

In this study, we have established the optimum design condition of pore-filled anion-exchange membrane for all-vanadium redox flow battery (VRFB). From the experimental results, it was proven that the membrane design factors that have the greatest influence on the charge-discharge performance of VRFB are the ion exchange capacity, the porosity of substrate film, and the crosslinking degree. That is, the ohmic loss and the crossover of active materials in VRFB were shown to be determined by the above factors. In addition, two methods, i.e. reducing the ion exchange capacity at low crosslinking degree and increasing the crosslinking degree at high ion exchange capacity, were investigated in the preparation of pore-filled anion-exchange membranes. As a result, it was found that optimizing the crosslinking degree at sufficiently high ion exchange capacity is more desirable to achieving high VRFB charge-discharge performances.

• Membrane Journal
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• v.33 no.5
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• pp.257-268
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• 2023

Membrane capacitive deionization (MCDI) is a variation of the conventional CDI process that can improve desalination efficiency by employing an ion-exchange membrane (IEM) together with a porous carbon electrode. The IEM is a key component that greatly affects the performance of MCDI. In this study, we attempted to derive the optimal fabricating factors for IEMs that can significantly improve the desalination efficiency of MCDI. For this purpose, pore-filled IEMs (PFIEMs) were then fabricated by filling the pores of the PE porous support film with monomers and carrying out in-situ photopolymerization. As a result of the experiment, the prepared PFIEMs showed excellent electrochemical properties that can be applied to various desalination and energy conversion processes. In addition, through the correlation analysis between MCDI performance and membrane characteristic parameters, it was found that controlling the degree of crosslinking of the membranes and maximizing permselectivity within a sufficiently low level of membrane electrical resistance are the most desirable membrane fabricating condition for improving MCDI performance.