• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.240-245
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• 1997

• Polymer(Korea)
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• v.29 no.6
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• pp.593-598
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• 2005

This work studied the loading capabilities and release behaviors of poly(ethylene-alt-maleic anhydride) (PEMAh)/poly(4-vinyl pyridine) (P4VP) multilayer films formed by the layer-by-layer(LbL) sequential self-assembly method, using Rodamine 6G(R6G) as an indicator. Thickness of the multilayer, and loading and subsequent release behavior of R6G from the multilayer were studied using UV-visible spectroscopy. The amount of R6G loaded in multilayer film increased linearly with increasing film thickness. pH-Sensitive permeability was observed, where lower pH environments increased both release rate and release amount. By additional assembling of PEMAh/poly(ethyleneimine) (PEI) capping layers on top of (PEMAh/P4VP)n multilayers, the release of R6G was better controlled.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.482-486
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• 2005

The biodegradable poly(${\varepsilon}$-caprolactone)(PCL)/poly(ethylene imine)(PEI) microcapsules containing $Al_2O_3$ and fragrant oil were prepared with different PEI contents. The effects of stirring rate and concentration of the surfactant on the diameter and morphologies of microcapsules were investigated by using scanning electron microscope (SEM). Thermal behaviors were studied by using a differential scanning calorimetry(DSC), and the release behaviors of fragrant oil from microcapsule were characterized by UV/vis. spectrophotometer. As a result, the average particle size of the microcapsules decreased with increasing the stirring rate or concentration of the surfactant. The surface morphologies of the microcapsules were changed from smooth surfaces to skin-like rough surfaces as increasing the PEI content. These results were mainly due to the increased hydrophilic groups at the microcapsule surfaces, resulting in increasing the release rate of fragrant oil in the microcapsules studied.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.173-187
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• 2015

The goal of present work is the preparation of a novel positively charged nanofiltration (NF) membrane and its development for the cation removal of aqueous solutions. This NF membrane was fabricated by the surface modification of polysulfone (PSf) ultrafiltration support. The active top-layer was formed by interfacial cross-linking polymerization of poly(ethyleneimine) (PEI) with p-xylylene dichloride (XDC) and then quaternized with methyl iodide to form a perpetually positively charged layer. In order to improve the efficiency of nanofiltration membrane, the concentration of PEI, XDC and methyl iodide solutions, PEI coating and cross-linking time have been optimized. As a result, a high water flux and high $CaCl_2$ rejection (1,000 ppm) was obtained for the composite membrane with values of $18.29L/m^2.h$ and 93.62% at 4 bar and $25^{\circ}C$, respectively. The rejections of NF membrane for different salt solutions followed the order of $Na_2SO_4$ < $MgSO_4$ < NaCl < $CaCl_2$. Molecular weight of cut off (MWCO) was calculated via retaining of PEG solutions with different molecular weights that finally, it revealed the Stokes and hydrodynamic radius of 1.457 and 2.507 nm on the membrane selective layer, respectively. The most efficient positively charged nanofiltration membrane exhibited a $Ni^{2+}$ rejection of 96.26% for industrial wastewater from Shamse Hadaf Co. (Kashan, Iran).

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.693-697
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• 2016

In this study, we fabricated the catalysts for enzymatic biofuel cell anode with carbon nanotube (CNT), glucose oxidase (GOx) and various molecular weights branched poly(ethyleneimine)(bPEI) and terephthalaldehyde (TPA) as cross-linker. In case of GOx/bPEI/CNT using only physical entrapments for immobilization, the molecular weights of bPEI didn't affect to electrochemical performances and long term stability. but that of the catalysts cross linked via TPA (TPA[GOx/bPEI/CNT]) improved and the mass transfer of glucose to FAD was interrupted as increasing of the bPEI's molecular weights. Furthermore, it was confirmed that the optimum molecular weight of PEI for TPA [GOx/bPEI/CNT]) structure is 750k that showed marvelous high performance (maximum power density of $0.995mW{\cdot}cm^{-2}$).

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.400.1-400.1
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• 2016

Interfacial engineering approaches as an efficient strategy for improving the power conversion efficiencies (PCEs) of inverted polymer solar cells (iPSCs) has attracted considerable attention. Recently, polymer surface modifiers, such as poly(ethyleneimine) (PEI) and polyethylenimine ethoxylated (PEIE), were introduced to produce low WF electrodes and were reported to have good electron selectivity for inverted polymer solar cells (iPSCs) without an n-type metal oxide layer. To obtain more efficient solar cells, quantum dots (QDs) are used as effective sensitizers across a broad spectral range from visible to near IR. Additionally, they have the ability to efficiently generate multiple excitons from a single photon via a process called carrier multiplication (CM) or multiple exciton generation (MEG). However, in general, it is very difficult to prepare a bilayer structure with an organic layer and a QD interlayer through a solution process, because most solvents can dissolve and destroy the organic layer and QD interlayer. To present a more effective strategy for surpassing the limitations of traditional methods, we studied and fabricated the highly efficient iPSCs with mono-layered QDs as an effective multi-functional layer, to enhance the quantum yield caused by various effects of QDs monolayer. The mono-layered QDs play the multi-functional role as surface modifier, sub-photosensitizer and electron transport layer. Using this effective approach, we achieve the highest conversion efficiency of ~10.3% resulting from improved interfacial properties and efficient charge transfer, which is verified by various analysis tools.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.179-183
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• 2015

In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ($[GOx/GNR]_nPEI/CNT$). To investigate the impact of $[GOx/GNR]_nPEI/CNT$ on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that $[GOx/GNR/PEI]_2/CNT$ is the best layer. Its glucose sensitivity is $13.315{\mu}AmM^{-1}cm^{-2}$. When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within $[GOx/GNR/PEI]_2/CNT$, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the $[GOx/GNR/PEI]_3/CNT$ is limited to the surface reaction and the reaction is quasi-reversible.