• Polymer(Korea)
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• v.29 no.2
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• pp.172-176
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• 2005

Environmentally friendly water dispersion polyurethanes containing fluorine were prepared with a fluorinated polyol having $62\%$ of fluorine $(Fluorolink^{(R)}\;M_n\;1000)$. In order to control the fluorine contents of the synthesized polyurethanes polytetramethylene glycol (PTMG2000) and $Fluorolink^{(R)}$ were mixed at assigned ratios and reacted with isophorone diisocyanate (IPDI) as a diisocyanate used. Introducing hydrophilic anion to the polymer chain was achieved by applying dimethyl propionic acid (DMPA). The ionic groups were neutralized with triethyl amine (TEA) before dispersion into water. Chain extension was executed by adding ethylene diamine at the final stage. Mechanical properties of the polymers showed that modulus increased with increasing $Fluorolink^{(R)}$ content. Surface energy values obtained from contact angle measurement decreased with increasing $Fluorolink^{(R)}$ content up to $20\%$. We expect that the synthesized polyurethanes present reliable effect from the fluorine atoms incorporated even at a small amount of $Fluorolink^{(R)}$.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.262-268
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• 1999

Polycarbonate (PC) and Polymethylmethacrylate (PMMA) surface was modified by ion assisted reaction (IAR) technique to obtain the hydrophilic functional groups and improve the wettability. In conditions of ion assisted reaction, ion beam energy was changed from 500 to 1500eV, and ion dose and oxygen gas blown rate were fixed $1\times10^{16}$ ions/$\textrm{cm}^2$ and 4ml/min, respectively. Wetting angle of water on PC and PMMA surface modified by $Ar^+$ ion without blowing oxygen at 4ml/mon showed $5^{\circ}$ and $10^{\circ}$. Changes of wetting angle with oxygen gas and $Ar^+$ ion irradiation were explained by considering formation of hydrophilic group due to a reaction between irradiated polymer chain by energetic ion irradiation and blown oxygen gas. X-ray photoelectron spectroscopy analysis shows that hydrophilic groups such as -C-O, -(C=O)- and -(C=O)-O- are formed on the surface of polymer by chemical interaction. The polymer surface modification using ion assisted reaction only changed the surface physical properties and sept the bulk properties. In comparison with other modification methods, the surface modification by IAR treatment was chemically stable and enhanced the adhesion between metal and polymer surface. The applications of various kinds of polymer surface modification methods, metal and polymer surface. The applications of various kinds of polymer surface modification could be appled to the new materials about hydrophilic surface properties by IAR treatment. The adhesion between metal film and polymer measured by Scotch tape test whether the hydrophilic surfaces could improve the adhesion strength or not.

• Membrane Journal
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• v.23 no.3
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• pp.204-210
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• 2013

Recently, many applications with grapheneoxide (GO) have been reported. But GO membrane for water treatment has not been developed. In this study we prepared polyvinylidene difluoride (PVdF) nanofiber/GO hybrid membrane (FG) for the microfiltration application. The PVdF substrate membrane was prepared by using the electrospinning method with a solution of PVdF in N,N-dimethylacetamide (DMAc) and acetone. GO sheets used in this study were prepared by modified Hummer's method. The PVdF/GO hybrid membrane was finally prepared by spraying the GO solution dispersed in ethanol on the PVdF nanofiber. The successfully prepared FG was thoroughly examined by SEM, Raman, contact angle, porometer and UTM, and water-flux was measured with designed cell (Dead-End Cell). From the contact angle results, it was found that the surface of FG membrane was reformed by hydrophilic property and the water permeability was increased about 2.5 times than that of the nascent PVdF membrane, indicating the possible alternative of the commercial MF membrane.

• Journal of fish pathology
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• v.24 no.2
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• pp.75-84
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• 2011

The amino acid sequence of glycoprotein of Korean VHSV isolate (KR'01-1) was analyzed using the DNAStar Protean system. Based on the flexibility, hydrophilicity, antigenic index and surface probability, three regions (Gp1, Gp2 and Gp3) were selected as potential antigenic determinants. Three oligopeptides containing the amino acid sequences of the three regions were synthesized and polyclonal antibodies were raised against them. The activities of the antibodies were analyzed by Western blotting and virus neutralization test. The results showed that antibodies raised against oligopeptides Gp1 and Gp2 neutralized the infectivity of VHSV, suggesting that they can be possible candidates for subunit vaccines against VHS diseases in olive flounder.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.347-352
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• 2006

분자전해질연료전지 내의 다공성 기체확산층은 반응가스의 확산과 전자이동통로의 역할을 수행할 뿐만 아니라 전기화학반응에 의해 공기극에서 생성된 수분(기상 혹은 액상)을 반응면으로부터 분리판 채널 방향으로 이동시켜 배출시키는 중요한 역할을 한다. 따라서 물관리를 통한 성능향상을 위해서는 기체 확산층의 구조 및 재료특성에 대한 심도 릴은 연구가 필요하다. 실제 단위전지 체결시 기체확산층은 분리판의 리브(rib)에 의해 눌리게 되며, 그 부분의 기공 크기 분포의 변화를 야기한다. 또한 리브 전단부분에서 탄소 섬유가 손상을 입으며, 탄소 섬유를 감싸고 있는 PTFE coating이 벗겨지게 되어 표면화학적 특성이 달라진다. 본 연구에서는 단위전지 체결 시 분리판에 의해 눌리는 기체확산층의 기공 크기 분포 변화를 측정하였으며, 기공의 소수성에서 친수성으로의 변화를 알아보았다. Mercury 기공 측정기와 PMI 기공 측정기는 큰 기공 분포의 변화에, 질소의 흡/탈착을 이용한 BET 방식은 작은 크기의 기공 분포 변화 관찰에 사용되었다. 체결압에 의한 탄소섬유의 구조적 변화와 아울러 표면의 습윤 정도의 변화를 XPS와 물/알콜 Uptake를 이용해 알아보았다. 이 연구를 바탕으로 물관리를 통한 연료전지 성능 향상을 위한 최적 GDL 선정에 기반이 되는 자료를 도출하였다.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.645-649
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• 2009

Liquid desiccant cooling technology can supply cooling by using waste heat and solar heat which are hard to use effectively. For compact and efficient design of a dehumidifier, it is important to sustain sufficient heat and mass transfer surface area for water vapor diffusion from air to liquid desiccant on heat exchanger. In this study, the plate type heat exchanger is adopted which has extended surface, and hydrophilic coating and porous layer coating are adopted to enhance surface wettedness. PP(polypropylene) plate is coated by porous layer and PET(polyethylene terephthalate) non-woven fabric is coated by hydrophilic polymer. These coated surfaces have porous structure, so that falling liquid film spreads widely on the coated surface foaming thin liquid film by capillary force. The temperature of liquid desiccant increases during dehumidification process by latent heat absorption, which leads to loss of dehumidification capacity. Liquid desiccant is cooled by cooling water flowing in plate heat exchanger. On the plate side, the liquid desiccant can be cooled by internal cooling. However the liquid desiccant on extended surface should be moved and cooled at heat exchanger surface. Optimal mixing and distribution of liquid desiccant between extended surface and plate heat exchanger surface is essential design parameter. The experiment has been conducted to verify effective surface treatment and distribution characteristics by measuring wall side flow rate and visualization test. It is observed that hydrophilic and porous layer coating have excellent wettedness, and the distribution can be regulated by adopting holes on extended surface.

• Polymer(Korea)
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• v.39 no.2
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• pp.293-299
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• 2015

Conductive microcellular foams consisted of polystrene (PS) and polydopamine-coated carbon nanotube (PDA-CNT) were prepared via high internal phase emulsion (HIPE) polymerization and their morphology and electrical conductivity were investigated. CNT as a conductive nanofiller was modified to PDA-CNT by coating with hydrophilic PDA on the surface of CNT to increase aqueous phase dispersion and emulsion stability. It was possible to prepare the HIPEs having higher PDA-CNT content and the resultant foams having improved conductivity due to its good dispersion. The foams showed the morphology of interconnected cell structure. As PDA-CNT content increased, yield stress and storage modulus increased and cell size reduced. The PDA-CNT content showing electrical percolation threshold was ca. 0.58 wt% and the conductivity at PDA-CNT content of 5 wt% was increased to $10^{-3}S/m$.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.101-107
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• 1995

As the surfactants that were used in micellar reaction, emulsion polymerization and phase-transfer reaction etc. have the problems, the cleavable surfactant was converted to inactive compound after such as the reaction in the condition. Because 1, 3-dioxolane ring by ketal or acetal reactioc is lack of stability in acid condition, it is easily made to acid-hydrolysis. And cmc value of the surfactant is assumed $1.0{\times}10^{-5}mol/L$ and surface tension in cmc is 31 dyne/cm. Compared with other surfactant, this surfactant foam property is not better. But emulsion property was relatively good. According as acid-hydrolysis property was observed the interface tension change between aqueous solution and benzene by the variation of pH and time, this surfactant was made to hydrolysis within about 300minutes in pH 1${\sims}$4. Therefore this surfactant is expected to be a good emulsifier that has the bad foam property and the acid-hydrolysis property in acid condition.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.146-154
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• 2019

In this study, alkoxysilane-functionalized amphiphilic polymer (AFAP), which have hydrophilic segment and hydrophobic segment functionalized by alkoxysilane group at the same backbone, was synthesized and used as a dispersant and control agent for reaction rate in the preparation of colloidally stable organic-inorganic (O-I) hybrid sols. After reaction with fluorosilane compounds, fluorinated O-I hybrid sols were prepared and coated onto glass substrate to form hydrophobic O-I hybrid coating films through low-temperature curing process. Surface hardness and hydrophobicity of cured coating films were varied with type of solvent and composition of AFAP and fluorinated alkoxysilane compounds. At appropriate solvent and composition of fluorinated alkoxysilane compounds, O-I hybrid coating film having high transparency and surface hardness could be prepared, which could be applicable to cover window of solar cell and displays.