• Membrane Journal
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• v.25 no.5
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• pp.391-397
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• 2015

The porous support polyvinylidene fluoride (PVDF) with a salting out based on the hollow fiber membrane polyethyleneimine (PEI) and polyvinylsulfonic acid (PVSA) by coating with by phase separated and pressurization (PSP) method to produce a multilayer membrane. The resulting membranes were characterized under the various conditions, such as the heat treatment temperature, coating concentration, feed concentration, cross-linking time and cross-link agent concentration in terms of flux and rejection rate for NaCl 100 ppm solution at 4 atm. The best results were PEI 20,000 ppm and PVSA 1,000 ppm, PEI 15% with a 2% malic acid aqueous solution coated by PSP method the hollow fiber membrane heat-treated for 1 minute showed flux 24.3 LMH, the rejection of 82.1%.

• Membrane Journal
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• v.6 no.4
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• pp.213-218
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• 1996

Cholesterol-containing monomeric surfactants were synthesized, and sonicated in water to form a vesicle solution. This vesicle solution was dried to construct a membrane which had a molecular multilayer structure. Using UV irradiation the surfactants in this membrane were polymerized and molecular weight was determined. Using a X-ray diffractomelet, the thickness of one layer and the regularity of the multilayer were measured.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.842-846
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• 2008

Layer-by-layer assembled multilayers of poly(ethersulfone)s were deposited on the surface of Nafion membrane for the application of direct methanol fuel cells (DMFC). Aminated poly(ethersulfone) (APES) and sulfonated poly(ethersulfone) (SPES) were used as a polycation and a polyanion for fabrication of the multilayer films. UV/Vis absorption spectroscopy verified a linear build-up of the multilayers of APES and SPES on the surface of Nafion. Thin multilayer films deposited on the Nafion membrane enabled methanol permeability of the membrane to decrease by 78% in comparison with the pristine Nafion. The performance of DMFCs in concentrated methanol was highly enhanced by using the multilayer modified Nafion.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.187-193
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• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

• Korean Journal of Materials Research
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• v.20 no.9
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• pp.451-456
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• 2010

A promising candidate material for a $H_2$ permeable membrane is SiC due to its many unique properties. A hydrogen-selective SiC membrane was successfully fabricated on the outer surface of an intermediate multilayer $\gamma-Al_2O_3$ with a graded structure. The $\gamma-Al_2O_3$ multilayer was formed on top of a macroporous $\alpha-Al_2O_3$ support by consecutively dipping into a set of successive solutions containing boehmite sols of different particle sizes and then calcining. The boehmite sols were prepared from an aluminum isopropoxide precursor and heated to $80^{\circ}C$ with high speed stirring for 24 hrs to hydrolyze the precursor. Then the solutions were refluxed at $92^{\circ}C$ for 20 hrs to form a boehmite precipitate. The particle size of the boehmite sols was controlled according to various experimental parameters, such as acid types and acid concentrations. The topmost SiC layer was formed on top of the intermediate $\gamma-Al_2O_3$ by pyrolysis of a SiC precursor, polycarbosilane, in an Ar atmosphere. The resulting amorphous SiC-on-$Al_2O_3$ composite membrane pyrolyzed at $900^{\circ}C$ possessed a high $H_2$ permeability of $3.61\times10^{-7}$ $mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$ and the $H_2/CO_2$ selectivity was much higher than the theoretical value of 4.69 in all permeation temperature ranges. Gas permeabilities through a SiC membrane are affected by Knudsen diffusion and a surface diffusion mechanism, which are based on the molecular weight of gas species and movement of adsorbed gas molecules on the surface of the pores.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.553-559
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• 2013

We make several membranes with multilayer structure and characterize protective performance in various ways. Multilayer membrane is composed of shell fabric, support membrane, functional polymer membrane and liner fabric. In this research, we apply cellulose acetate derivatives as base polymer in functional polymer membrane and characterize water resistance, water vapor permeation, protective performance against DMMP and aerosol. Test results show that cellulose based polymer with polyethyleneimine possess performance with good water vapor permeation and excellent protective capability against DMMP equivalent to Saratoga type's protective suits. Also, these materials possess aerosol protective performance and water resistance.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1142-1146
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• 1996

Cholesterol-containing surfactant was synthesized, and it was sonicated with monomer in water to form a vesicle solution. This vesicle solution was dried to construct a membrane which had a molecular multilayer structure. Using UV irradiation the monomer in this membrane were polymerized, and then surfactant was extracted by organic solvent. Using a X-ray diffractometer, the thickness of one layer and the regularity of the multilayer were measured. And scanning electron microscopy was conducted for fractured polymer film.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.763-767
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• 1998

Cholesterol-containing surfactant was synthesized, and it was sonicated with monomer [tetradeca(ethylene glycol) diacrylate] in water to from a vesicle solution. This vesicle solution was dried to construct a membrane which had a molecular multilayer structure. The monomer which stay in this membrane was polymerized with photoinitiation, and then surfactant was extracted by organic solvent. The physical properties of the two dimensional polymer network were measured, and these physical properties are tensile strength, elongation, and swelling.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.142-145
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• 2004

Anion-exchange porous hollow-fiber membranes with a thickness of about 1.2 mm and a pore size of about $0.30{\mu}m$ were used as a supporting matrix to immobilize cycloisomaltooligosaccharide glucanotransferase (CITase). CITase was immobilized to the membrane via anion-exchange adsorption and by subsequent enzymatic cross-linking with transglutaminase, the amount of which ranged from 3 to 110 mg per g of the membrane. The degree of enzyme multilayer binding was equivalent to 0.3 to 9.8. Dextran, as the substrate, was converted into seven- to nine-glucose-membered cycloisomaltooligosaccharides (CI-7, -8, and -9) at a maxi mum yield of $28\%$ in weight at a space velocity of 10 per hour during the permeation of $2.0(w/w)\%$ dextran solution across the CITase-immobilized porous hollow-fiber membrane.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.30-33
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• 1995

By using X-ray double crystal diffraction technique the multilayer structure composed of glass membrane, platinum film and $\alpha Al_2O_3$ substrate has been studied. It is found the stress is produced in the film by thermal mismatch within multilayer materials. The measuring results of thin film platinum resistors show that the stress were induce resistance change of device and different stress status will produce add resistance in different direction. Selecting proper glass material can make opposite stress in Pt film and opposite add resistance due to thermal mismatch. The reliability of Pt resistor has been improved with method of this stress compensation.