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제올라이트를 이용한 Polyacrylonitrile의 합성
황덕근 ( Duck Kun Hwang ),정경택 ( Kyong Teak Jung ),설용건 ( Yong Gun Shul ) 한국공업화학회 2002 공업화학 Vol.13 No.8
제올라이트를 이용하여 polyacrylonitrile (PAN)을 합성하였다. 단량체인 acrylonitrile를 탈수화시킨 Na-Y와 Na-β제올라이트에 흡착시킨 후에 라디칼 중합을 실시하였다. 제올라이트 기공 구조 안에서 중합된 PAN은 hydrofluoric acid를 사용하여 추출하였다. 제올라이트를 이용하여 합성된 PAN은 용액중합을 통해서 합성된 PAN에 비해서 결정화도와 이소탁틱 입체 규칙성이 증가된 것을 X선회절과 핵자기공명분석을 이용하여 확인하였다. 추출된 PAN의 열적 물리적 특성은 시차주사열량계와 겔투과크로마토그라피를 이용하여 확인하였다. Polyacrylonitrile (PAN) has been prepared by using a zeolite as a host. After introduction of acrylonitrile monomer, they were polymerized with a radical initiator in Na-Y and Na-β zeolite channels, followed by extraction with hydrofluoric acid. X-ray diffraction and ^13C nuclear magnetic resonance results showed that the crystallinity and isotacticity of extracted PAN was higher than those of bulk PAN prepared under the solution polymerization. Thermal and physical properties of extracted PAN were also investigated using differential scanning calorimeter and gel permeation chromatography.
Choi, Sua,Hwang, Duck Kun,Lee, Heon Sang 한국탄소학회 2014 Carbon Letters Vol.15 No.4
Blends of poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and graphene oxide (GO) were prepared by solution casting method. Calorimetric thermal properties of the blends were investigated. The Tgs of PVA/PEI blends were higher than the Tgs of either of the component polymers at low concentrations of PEI. These abnormal increases of Tgs may be due to the negative entropy of mixing which is associated with strong hydrogen bonding between PVA and PEI. The degree of depression of T0ms was not reduced by the negative entropy of mixing, since strong hydrogen bonding also causes an increase in the magnitude of negative χ between PVA and PEI. The Tg of PVA was increased significantly by adding 0.7 wt.% GO into PVA. The magnitude of negative χ was increased by adding GO into the blends of PVA and PEI.
Jung, Rockhoon,Hwang, Duck-Kun,Choi, Han Shin,Kim, Hyun-Jae,Kim, Hyun-Jong American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.12
<P>The surface of commercial carbon black was modified by pyrolysis of acetonitrile in attempt to obtain the graphitic carbon coating layer. It was confirmed that the surface of carbon black was partially graphitized, having 0.23 of graphitization index and 1.87 nm of mean stack height. From the electrochemical oxidation test of carbon, the carbon-coated carbon black showed higher corrosion resistance than the untreated carbon black although the core of the carbon black support still remained untreated. When it was applied to the support for platinum electrocatalyst, the enhanced stability was observed. From those corrosion tests as well as XPS results, it can be suggested that the partially crystalline graphitic carbon surface facilitates the relatively more reduced surface of platinum.</P>
Ahn, Mi Young,Jee, Sang Duck,Lee, Byung Mu,Yeon, Ji-Hye,Park, Kun-Koo,Hwang, Jae Sam,Yun, Eun Young Taylor Francis 2010 Journal of toxicology and environmental health. Pa Vol.73 No.21
<P>The molecular mechanisms underlying the glucose-lowering effects of Isaria sinclairii (Cicada Dongchunghacho), a fungus cultured on silkworm, are not fully elucidated. Thus the glucose-lowering effects of I. sinclairii as potential an antidiabetic agent were investigated in C57BL/6 obese (ob/ob) mice over a 6-mo period. For a period of 26 wk, ob mice were administered either 5 or 10% (w/w) I. sinclairii powder (IS), 10% dry mulberry leaf powder (ML), or 10% silkworm (SW) powder in the standard diet while a control group received only standard diet. The ML and SW preparations served as positive controls. Isaria sinclairii at 10% in the diet was more effective in reducing body weight compared to 10% ML, 10% SW, or 5% I. sinclairii. The fall in blood glucose levels in the groups treated for 26 wk was greater in both IS groups at 1 mo compared to ML or SW but equal in all groups at 6 mo. Microarray analyses were performed with a mouse 7.4K cDNA clone set array to identify the gene-expression profiles for the IS-, ML-, and SW-exposed ob mouse liver. The 10% IS group, compared to control, showed that 15 genes including glucokinase (Gk-rs1) and LDL receptor relating protein 1 were upregulated and 12 genes including cell translocation gene2 (antiproliferative) and hydroxyprostaglandin dehydrogenase (Hpgd 15) were downregulated. Upregulation of Gk-rs 1 and downregulation of Hpgd 15 were previously shown to occur in drug-induced suppression of diabetes. With ML, Lepr (leptin receptor), Pik3cb (phosphatidylinositol 3-kinase), and Prodh (proline dehydrogenase), related to suppression of diabetes, were upregulated. In the case of SW, the enzymes (G2an, alpha glucosidase 2) and Mmp9 (matrix metalloproteinase 9) involved in elevation of blood glucose levels were both downregulated. Data suggest that I. sinclarii is effective in lowering blood glucose due to the upregulation of glucokinase (Gk-rs1) and downregulation of hydroxyprostaglandin dehydrogenase (Hpgd 15), both associated with suppression of diabetes, indicating that microarray analysis is a useful tool to assess pharmacological potency of therapeutic compounds.</P>
Lee, Ho-Nyun,Shin, Chi-Ho,Hwang, Duck Kun,Kim, Haekyoung,Oh, Kyeongseok,Kim, Hyun-Jong Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.644 No.-
<P><B>Abstract</B></P> <P>In this study, a novel pressurized polyol method is proposed to synthesize aluminum-doped ZnO (AZO) nanoclusters without utilizing additional thermal treatment to avoid the merging of nanoclusters. The size of the AZO nanoclusters range from 100 to 150nm with a resistivity of 204Ωcm. The AZO nanoclusters primarily consist of approximately 10-nm nanocrystals that form a spherically clustered morphology. A two-stage growth model has been proposed based on the results of scanning electron microscopy and transmission electron microscopy images, nanocluster sizes, and X-ray diffraction patterns. The primary AZO nanocrystals first nucleate under pressurized conditions and then spontaneously aggregate into larger nanoclusters. Optically, the AZO nanoclusters exhibit a significant decrease in the near-infrared (NIR) transmittance compared to pure ZnO nanoparticles. The NIR blocking efficiency of AZO nanoclusters reached 85%. Moreover, the doping efficiency, resistivity, and NIR transmittance of AZO nanoclusters are influenced by the reaction time in the pressurized polyol solution. On the other hand, the reaction time has no effect on the particle size and crystallinity. An optically transparent coating for the AZO nanoclusters, which consisted of iso-propanol solvent and ultraviolet-curable acrylic binder, was also demonstrated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low-temperature pressurized polyol method synthesized Al-doped ZnO nanoclusters. </LI> <LI> Reaction time affected the doping efficiency, resistivity, and NIR transmittance. </LI> <LI> The near-IR blocking efficiency of Al-doped ZnO (AZO) nanoclusters reached 85%. </LI> <LI> AZO nanocluster coatings could be used for heat reflectors or artificial glasses. </LI> </UL> </P>
Jeong Suk Kim,Jin Hyo Park,Kyung Kyoon Kim,Duck Kun Hwang,Woon-Yong Choi,안성훈,Myung-Chang Kang 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.10
This study is to investigate the nitrogen ion implantation process in PC (Polycarbonate) composite for improving surface electrical conductivity. The suggested process is applied for the thin wall shape polymer which is composed of low carbon black and carbon fiber in order to increase electric conductivity. The acceleration voltage which is relatively low 3~50 keV in ion implantation process is used to obtain the thin conductive surface layer around 2 micrometer. The surface electrical conductivity of PC composite is realized up to below 106 Ω/cm2 by controlling ion dose without degrading mechanical properties. This technology can be adopted to make conductive plastic product which is applicable for static electricity prevention and electromagnetic wave masking. In order to evaluate the effect of surface modification of PC by nitrogen ion implantation, its surface resistance, tensile strength, tensile elongation, and half-life have been measured. The properties of PC/CF and PC/CB increased surface resistance and tensile strength. Also, the properties of PC/CF and PC/CB significantly decreased tensile elongation and half-life.