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Curing behavior of liquid crystalline epoxy/DGEBA blend
Jang, Jyongsik,Lee, Jun Yeob Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.106 No.4
<P>The effect of liquid crystalline epoxy (LCE) resin on the curing behavior and thermomechanical properties of diglycidylether of bisphenol A (DGEBA) was investigated. LCE was blended with DGEBA and curing behavior of the blend was studied according to LCE content in the blend. Curing of DGEBA was accelerated and thermomechanical properties of DGEBA were considerably improved by the addition of LCE, which acted as a molecular reinforcement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007</P>
Fabrication of mesoporous polymer/silica hybrid using surfactant-mediated sol–gel method
Jang, Jyongsik,Bae, Joonwon Elsevier 2006 Journal of non-crystalline solids Vol.352 No.38-39
<P><B>Abstract</B></P><P>A mesoporous polymer/silica hybrid was fabricated by a surfactant-mediated sol–gel method. Under our experimental conditions, acrylonitrile (AN) monomer was located at the exterior of micelles and the sol–gel reaction of tetraethoxyorthosilicate (TEOS) proceeded concurrently with the polymerization reaction of the AN monomer. In other words, the micelle/polyacrylonitrile/silica precursor was synthesized through the radical polymerization accompanied with a hydrolysis/condensation single reaction in a reaction system. This is a unique characteristic of our methodology, which embraces the concept of ‘micelle templating’. The pore diameter of the mesoporous polymer/silica hybrid could be tuned by varying the spacer length and concentration of surfactants. Furthermore, compared with conventional mesoporous carbons, the carbonized mesoporous polymer/silica hybrids displayed an enhanced electrical performance favorable for use as a supercapacitor.</P>
Fabrication and characterization of polyaniline coated carbon nanofiber for supercapacitor
Jang, Jyongsik,Bae, Joonwon,Choi, Moonjung,Yoon, Seong-Ho Elsevier 2005 Carbon Vol.43 No.13
<P><B>Abstract</B></P><P>Polyaniline coated carbon nanofiber was fabricated using one-step vapor deposition polymerization technique. Fourier transform infrared (FT-IR) spectra and transmission electron microscope (TEM) images indicated that uniform and ultrathin conducting polymer layers were formed on the carbon nanofiber surfaces regardless of the coating thickness. It was also confirmed that the thickness of polyaniline layer could be conveniently tuned by the feeding amount of monomer. The coating thickness was dependent on initiator/monomer ratio, the vacuum pressure of reaction chamber and polymerization temperature. Among them, the vacuum pressure was a major factor to control the coating thickness of polyaniline onto the carbon nanofiber surface. In addition, the electrochemical analysis demonstrated that polyaniline coated carbon nanofiber showed an improved performance as supercapacitor. The specific capacitance of polyaniline coated carbon nanofiber exhibited a maximum value of 264F/g when the thickness of polyaniline layer was ca. 20nm.</P>
Jang, Jyongsik,Lee, Kyung Jin,Kim, Younggeun Royal Society of Chemistry 2005 Chemical communications Vol.2005 No.30
<P>Polyimide nanotubes with tunable wall thickness were fabricated by a precursor impregnation method using an AAO template, and carbon nanotubes containing magnetic iron oxide were obtained using ferric chloride-embedded polyimide precursor by a carbonization process.</P> <P>Graphic Abstract</P><P>Polyimide nanotubes and their carbonized product with tunable wall thickness were fabricated by a precursor impregnation method and subsequent carbonization process using an AAO template. Magnetic properties could also be introduced into carbon nanotubes by carbonizing the Fe-embedded polyimide nanotube precursor. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b503831f'> </P>
Synthesis and curing of poly(glycidyl methacrylate) nanoparticles
Jang, Jyongsik,Bae, Joonwon,Ko, Sungrok Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of polymer science Part A, Polymer chemist Vol.43 No.11
<P>Glycidyl-functional polymer nanoparticles [poly(glycidyl methacrylate) (PGMA)] were fabricated with microemulsion polymerization. The successful fabrication of PGMA nanoparticles was confirmed by Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). A TEM image showed that the average diameter of the PGMA nanoparticles was approximately 10–28 nm and was fairly monodisperse. As the surfactant concentration increased, the average size of the nanoparticles decreased and approached an asymptotic value. A significant reduction of the nanoparticle size to the nanometer scale led to an enhanced number of surface functionalities, which played an important role in the curing reaction. The PGMA nanoparticles were cured with a low-temperature curing agent, diethylene triamine, to produce ultrafine thermoset nanoparticles. The low-temperature curing process was performed below the glass-transition temperature of PGMA to prevent the coagulation and deformation of the nanoparticles. A TEM image indicated that the cured PGMA nanoparticles did not exhibit interparticle aggregation and morphological transformation during curing. The average size of the cured PGMA nanoparticles was consistent with that of the pristine PGMA nanoparticles © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2258–2265, 2005</P> <B>Graphic Abstract</B> <P>Glycidyl-functional polymer nanoparticles with an average diameter of 10–28 nm were synthesized with microemulsion polymerization. The ultrasmall thermoset nanoparticles were fabricated through the curing reaction of poly(glycidyl methacrylate) nanoparticles with diethylene triamine at a low temperature without interparticle coagulation and morphological transformation. The average diameter of the cured nanoparticles was consistent with that of the pristine nanoparticles. <img src='wiley_img/0887624X-2005-43-11-POLA20706-gra001.gif' alt='wiley_img/0887624X-2005-43-11-POLA20706-gra001'> </P>
Jang, Jyongsik,Kim, Yura Royal Society of Chemistry 2008 Chemical communications Vol.2008 No.34
<P>Monodisperse nanoparticles with antimicrobial polymer shells were fabricated using a seeded copolymerization; they exhibited excellent antibacterial activities against gram-positive bacteria as well as gram-negative bacteria.</P> <P>Graphic Abstract</P><P>Monodisperse nanoparticles with antimicrobial polymer shells were fabricated using a seeded copolymerization; they exhibited excellent antibacterial activities. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b809137d'> </P>
Selective Fabrication of Polymer Nanocapsules and Nanotubes Using Cyclodextrin as a Nanoporogen
Jang, Jyongsik,Bae, Joonwon WILEY-VCH Verlag 2005 Macromolecular Rapid Communications Vol.26 No.16
<P>Summary: Polyacrylonitrile (PAN) nanocapsules and nanotubes were selectively synthesized by microemulsion polymerisation using β-cyclodextrin (β-CD) as a nanoporogen. Iron(III) chloride (FeCl<SUB>3</SUB>) was used as a structure-directing agent to fabricate polymer nanotubes. In addition, the average pore size of the PAN nanocapsules and nanotubes could be controlled with the concentration of β-CD.</P><P> <img src='wiley_img/10221336-2005-26-16-MARC200500292-gra001.gif' alt='wiley_img/10221336-2005-26-16-MARC200500292-gra001'> Graphic (a) TEM image of PAN nanocapsules; (b) SEM image of PAN nanotubes. </P>
Interfacial Studies of Organic/Inorganic Fibers for Advanced Material Application
Jang,Jyongsik 국립경상대학교 공과대학 부설 첨단소재연구소 1998 尖端素材 Vol.8 No.-
The interfacial adhesion strength in composite material is very important for its mechanical performance. There are many organic and inorganic reinforcing fibers such as ultra high modulus polyethylene (UHMPE) fiber, aramid fiber (Kevlar), glass fiber. The surface modification of these fibers and its characterization methods and their examples are summarized. For an additional example of fiber surface characterization method, the FT-IR analysis of an activated carbon fiber surface is described.