• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.169-171
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• 2003

Organic/inorganic hybrid membranes have been prepared and evaluated as polymer electrolytes in a polymer electrolyte membrane fuel cell (PEMFC). Previously, partially fluorinated poly (arylenether) was synthesized and the polymer was sulfonated by fuming sulfuric acid$(30\%\;SO_3)$. Modification of these polymers with coupling agent and inorganic materials was carried out to prepare membranes. Membranes cast from these materials were investigated in relation to the proton conductivity and weight loss at the room temperature. It was found that these membranes had a higher conductivity of $10^{-2}\;Scm^{-1}$ at the room temperature. But inorganic materials have leaked out from the hybrid membrane. If this problem is resolved, organic/inorganic hybrid membranes will become satisfactory Polymer electrolytes for the PEMFC.

• Macromolecular Research
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• v.15 no.6
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• pp.581-586
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• 2007

Cast DNA/polyethyleneimine (PEI) blend membranes containing different amounts of DNA were prepared using acid-base interaction and characterized with the aim of understanding the polymer electrolyte membrane properties. Two different molecular weights of PEI were used to provide the mechanical strength, while DNA, a polyelectrolyte, was used for the proton transport channel. Proton conductivity was observed for the DNA/PEI membrane and reached approximately $3.0{\times}10^{-3}S/cm$ for a DNA loading of 16 wt% at $80^{\circ}C$. The proton transport phenomena of the DNA/PEI complexes were investigated in terms of the complexation energy using the density functional theory method. In the case of DNA/PEI, a cisoid-type complex was more favorable for both the formation of the complex and the dissociation of hydrogen from the phosphate. Since the main requirement for proton transport in the polymer matrix is to dissociate the hydrogen from its ionic sites, this suggests the significant role played by the basicity of the matrix.

• Membrane Journal
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• v.15 no.1
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• pp.1-7
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• 2005

Polymer electrolyte membranes containing polysilsesquioxane (PSQ) spheres were prepared with the blend of sulfonated poly(ether ether ketone) (SPEEK) (60%) and poly(ether sulfone) (PES) (40%). The amount of PSQ spheres was fixed at 10 wt%. The prepared polymer electrolyte membranes were characterized in terms of methanol permeability, proton conductivity, and ion exchange capacity. In all cases, both methanol permeability and proton conductivity of the polymer electrolyte membranes containing PSQ spheres were lower than the values of Nafion 117 and higher than those of SPEEK/PES (6:4) blend without PSQ spheres. The experimental results indicated that the polymer electrolyte membranes containing MS64 and VTMOS spheres were the best choice in terms of the ratio of proton conductivity to methanol permeability.

• Korean Membrane Journal
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• v.11 no.1
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• pp.8-14
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• 2009

The sulfonated poly(styrene-divinylbenzene-acrylonitrile) (ST-DVB-AN) composite polymer electrolyte membrane based on the original PVC film was successfully synthesized to improve oxidative stability using semi-interpenetrated polymer network (semi-IPN). Weight gain ratio after copolymerization was enhanced by the DVB and AN contents, and the sulfonated membranes were characterized in terms of proton conductivity (k), ion exchange capacity (IEC), and water uptake ($W_U$). The effect of DVB content and AN addition were thoroughly investigated by comparing the resulted properties including oxidative stability. The obtained ST-DVB-AN composited semi-IPN membranes showed relatively high proton conductivity and IEC compared with Nafion117, and greatly improved oxidative stability of the synthesized membrane was obtained. This study demonstrated that a semi-interpenetrated sulfonated ST-DVB-AN composited membrane reinforced by PVC polymer network is a promising candidate as an inexpensive polymer electrolyte membrane for fuel cell applications.

• Membrane Journal
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• v.29 no.2
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• pp.80-87
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• 2019

Dye-sensitized solar cells (DSSCs) have attracted great attention as sustainable energy devices. The efficiency and long-term stability of DSSCs are greatly influenced by electrode materials and electrolytes. In this review, we focused on the electrolytes of DSSCs. Polymer electrolyte membranes have been proposed as an alternative to conventional liquid electrolytes in DSSCs. Conventional liquid electrolytes can exhibit a high efficiency, but due to some problems such as poor long-term stability of device and leakage of liquid, much interest in polymer electrolyte membranes continues to rise and the papers on polymer electrolytes membranes have been extensively reported recently. This review covers the concept and development of polymer electrolyte membranes for DSSCs, and discusses the efficiency and electrochemical properties of DSSCs, highlighting the modification of polymer matrix, the introduction of additives such as organic-inorganic plasticizers and ionic liquids.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05b
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• pp.57-60
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• 2004

Polymer electrolyte membranes have been studied widely in chloro-alkali electrolysis, cationic exchange resins, and fuel cell applications. Especially, sulfonated polyimide membranes have been suggested as a potential polymer electrolyte in PEMFC due to their excellent thermal stability and high proton conductivity.(omitted)

• Macromolecular Research
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• v.14 no.2
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• pp.214-219
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• 2006

Cast Nafion-based composite membranes containing different amounts of organic, nanorod-shaped polyrotaxane were prepared and characterized, with the aim of improving the properties of polymer electrolyte membranes for direct methanol fuel cell applications. Polyrotaxane was prepared using the inclusion-complex reaction between ${\alpha}$-cyclodextrin and poly(ethylene glycol) (PEG) of different molecular weights. The addition of polyrotaxane to Nafion changed the morphology and reduced the crystallinity. The conductivity of the composite membranes increased with increasing polyrotaxane content up to 5 wt%, but then decreased at higher polyrotaxane contents. Well-dispersed, organic polyrotaxane inside the membrane can provide a tortuous path for the transport of methanol, as the methanol permeability depends on the aspect ratio of polyrotaxane, which is controlled by the molecular weight of PEG. All of the Nafion-based, polyrotaxane composite membranes showed a higher selectivity parameter than the commercial Nafion films did.

• Membrane Journal
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• v.25 no.2
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• pp.171-179
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• 2015

Perfluorinated sulfonic acid ionomers (PFSAs) have been widely as solid electrolyte materials for polymer electrolyte membrane fuel cells, since they exhibit excellent chemical durability under their harsh application conditions as well as good proton conductivity. Even PFSA materials, however, suffer from physical failures associated with repeated membrane swelling and deswelling, resulting in fairly reduced electrochemical lifetime. In this study, pore-filling membranes are prepared by impregnating a Nafion ionomer into the pore of a porous PTFE support film and their fundamental characteristics are evaluated. The developed pore-filling membranes exhibit extremely high proton conductivity of about $0.5S\;cm^{-1}@90^{\circ}C$ in liquid water.

• Macromolecular Research
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• v.14 no.4
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• pp.449-455
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• 2006

Ionic cluster mimic, polymer electrolyte membranes were prepared using polymer composites of crosslinked poly(vinyl alcohol) (PVA) with sulfated-${\beta}$-cyclodextrins (${\beta}-CDSO_3H$) or phosphated-${\beta}$-cyclodextrins (${\beta}-CDPO(OH)_2$). When Nafion, developed for a fuel cell using low temperature, polymer electrolyte membranes, is used in a direct methanol fuel cell, it has a methanol crossover problem. The ionic inverted micellar structure formed by micro-segregation in Nafion, known as ionic cluster, is distorted in methanol aqueous solution, resulting in the significant transport of methanol through the membrane. While the ionic structure formed by the ionic sites in either ${\beta}-CDSO_3H$ or ${\beta}-CDPO(OH)_2$ in this composite membrane is maintained in methanol solution, it is expected to reduce methanol transport. Proton conductivity was found to increase in PVA membranes upon addition of ionized cyclodextrins. Methanol permeability through the PVA composite membrane containing cyclodextrins was lower than that of Nafion. It is thus concluded that the structure and fixation of ionic clusters are significant barriers to methanol crossover in direct methanol fuel cells.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.278-281
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• 2009

Proton exchange membrane is the key material for proton exchange membrane fuel cells (PEMFC). Currently widely-used perfluorosulfonic acid membranes have some disadvantages, such as low thermal stability, easy swelling, excessive crossover of methanol and high price etc. Other membranes, including sulfonated polymer, radiation grafted membranes, organic-inorganic hybrids and acid-base blends, do not satisfy the criteria for PEMFC, which set a barrier to the development and commercialization of PEMFC. Pore-filling type proton exchange membrane is a new proton exchange membrane, which is formed by filling porous substrate with electrolytes. Compared with traditional perfluorosulfonic acid membranes, pore-filling type proton exchange membranes have many advantages, such as non- swelling, low methanol permeation, high proton conductivity, low cost and a wide range of materials to choose. In this research, preparation methodology of pore-filling membranes by particularly using all hydrocarbon polymers and fuel cell performances with the membranes are evaluated.