• Title, Summary, Keyword: Polymer precursor

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Syntheses and Characterization of PBO Precursors Containing Dimethylphenoxy and/or MPEG Pendant Groups (Dimethylphenoxy와 MPEG 팬던트 그룹을 갖는 폴리벤즈옥사졸 전구체의 합성 및 특성)

  • Yoon Doo-Soo;Choi Jae-Kon;Jo Byung-Wook
    • Polymer Korea
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    • v.29 no.5
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    • pp.493-500
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    • 2005
  • Polyhydroxyamides(PHAs) having poly(ethylene glycol)methyl ether (MPEG) and/or dimethylphenoxy pendant groups were synthesized by solution polycondensation at low temperature. The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAC or DMAc/LiCl solution were in the range of $0.51\~2.31dL/g$. This precursor polymers were studied by FT-IR, $1H-NMR$, DSC, and TGA. Solubility of the precursors with higher MPEG unit was increased, especially the polymer having MPEG $(M_n=1100)$ was soluble or partially soluble in ethanol, methanol, and water as well as aprotic solvents, but the PBOs were nearly insoluble in a variety of solvents. PHAs were converted to polybenzoxazoles (PBOs) by thermal cyclization reaction with heat of endotherm. In case of the precursors having MPEG nit, the precursor polymers with a higher $M_n$ were fully cyclized at a lower temperature than one with a lower $M_n$.

Electrochemical Properties of Cross-linked Polyurethane Acrylate-Based Gel Polymer Electrolyte

  • Kim, Hyun-Soo;Kim, Sung-Il;Choi, Gwan-Young;Moon, Seong-In;Kim, Sang-Pil
    • Journal of the Korean Electrochemical Society
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    • v.5 no.4
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    • pp.197-201
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    • 2002
  • In this study, a gel polymer electrolyte was prepared from urethane acrylate and its electrochemical performances were evaluated. And, $LiCoO_2/GPE/graphite$ cells were prepared and their performances depending on discharge currents and temperatures were evaluated. The precursor containing $5 vol\%$ curable mixture had a low viscosity relatively. Ionic conductivity of the gel polymer electrolyte at room temperature and $-20^{\circ}C$ was ca. $5.9\times10^{-3}S{\cdot}cm^{-1}\;and\;1.7\times10^{-3}S{\cdot}cm^{-1}$, respectively. GPE showed electrochemical stability up to potential of 4.5V vs. $Li/Li^+.LiCoO_2/GPE/graphite$ cell showed a good high-rate and a low-temperature performance.

Gate dielectric based on organic-inorganic hybrid polymer in organic thin-film transistors

  • Lee, Seong-Hui;Jeong, Sun-Ho;Moon, Joo-Ho
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.727-729
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    • 2007
  • Inorganic-organic hybrid polymer provides various advantages including low-temperature process, high dielectric constant and direct photo-patterning. The hybrid dielectric was synthesized by the sol-gel process in which an acid-catalyzed solution of Si alkoxide and Zr alkoxide was used as a precursor. The electrical performance of transistors with hybrid dielectric was investigated.

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Fabrication and NOx Gas Sensing Properties of LaMeO3 (Me = Cr, Co) by Polymeric Precursor Method (Polymeric Precursor법에 의한 LaMeO3 (Me = Cr, Co)의 제조 및 NOx 가스 검지 특성)

  • Lee, Young-Sung;Shimizu, Y.;Song, Jeong-Hwan
    • Korean Journal of Materials Research
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    • v.21 no.8
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    • pp.468-475
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    • 2011
  • [ $LaMeO_3$ ](Me = Cr, Co) powders were prepared using the polymeric precursor method. The effects of the chelating agent and the polymeric additive on the synthesis of the $LaMeO_3$ perovskite were studied. The samples were synthesized using ethylene glycol (EG) as the solvent, acetyl acetone (AcAc) as the chelating agent, and polyvinylpyrrolidone (PVP) as the polymer additive. The thermal decomposition behavior of the precursor powder was characterized using a thermal analysis (TG-DTA). The crystallization and particle sizes of the $LaMeO_3$ powders were investigated via powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and particle size analyzer, respectively. The as-prepared precursor primarily has $LaMeO_3$ at the optimum condition, i.e. for a molar ratio of both metal-source (a : a) : EG (80a : 80a) : AcAc (8a) inclusive of 1 wt% PVP. When the as-prepared precursor was calcined at $700^{\circ}C$, only a single phase was observed to correspond with the orthorhombic structure of $LaCrO_3$ and the rhombohedral structure of $LaCoO_3$. A solid-electrolyte impedance-metric sensor device composed of $Li_{1.5}Al_{0.5}Ti_{1.5}(PO_4)_3$ as a transducer and $LaMeO_3$ as a receptor has been systematically investigated for the detection of NOx in the range of 20 to 250 ppm at $400^{\circ}C$. The sensor responses were able to divide the component between resistance and capacitance. The impedance-metric sensor for the NO showed higher sensitivity compared with $NO_2$. The responses of the impedance-metric sensor device showed dependence on each value of the NOx concentration.

A Study on the Fabrication of Hollow Glass Sphere by Using a Liquid-mix Precursor (혼합액상 전구체를 이용한 유리 중공구체의 제조에 관한 연구)

  • Lee, Yong Bin;Kim, Ki Do;Kim, Hee Taik
    • Applied Chemistry for Engineering
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    • v.10 no.8
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    • pp.1186-1191
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    • 1999
  • By using a liquid-mix precursor, we prepared the hollow glass spheres(HGS) as an additive of polymer compound which are used in the field of modifier, promoter, filler, and reinforcement. Liquid-mix precursor is a mixture of 40% sodium silicate aqueous solution, boric acid as a insolubilizing agent, and urea as a blowing agent. To obtain the precursor particles which are fed into a gas flame furnae, the above liquid-mix precursor was dried in oven and crushed with ball mill. We assumed the size of precursor particles ($53{\sim}63{\mu}m$, $63{\sim}180{\mu}m$), temperature of furnace($800{\sim}1200^{\circ}C$), and amount of urea(0~30 g) as the parameters affecting on the properties of HGS. As a result mean particle size of HGS increases with increasing the temperature of furnace and the amount of urea and with decreasing the size of precursor particles. Also, we found that incresing the amount of urea is related to a decrease of the crush strength of HGS.

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Synthesis and Photoalignment of Soluble Polyimides with Styrylpyridine Side Groups (스티릴피리딘 곁사슬기를 가지는 용해성 폴리이미드의 합성과 광배향)

  • Kim, Jin-Woo;Kim, Min-Woo;Ahn, Deuk-Kyoon;Kim, Woo-Sik
    • Polymer Korea
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    • v.33 no.3
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    • pp.207-212
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    • 2009
  • The precursor polyimide of the photoreactive polyimides(PI-SP6 and PI-SP12) was prepared from a derivative of 2, 2, 2-trifluoroethane dianhydride and 3,3'-dihydroxy-4,4'-diaminobiphenyl. PI-SP6 and PI-SP12 were then prepared by the polymer reactions of the precursor polyimide with photoreactive 2-styrylpyridine alkylene (hexylene and dodecylene) derivatives, respectively. The photoreactive polymers were soluble in organic solvents. The polymers showed the initial decomposition temperatures around $350^{\circ}C$. The glass transition temperatures of PI-SP6 and PI-SP12 were found to be $130^{\circ}C$ and $85^{\circ}C$, respectively. This result means that the latter polymer is more flexible than the former polymer. Their transmittance in the film state was 90% at $250^{\circ}C$, which indicates that the photosensitive polyimides with thermal stability have high optical transparency even at the high temperature. The respective dichroic ratios of PI-SP6 and PI-SP12 were found to be 0.01 and 0.03 at an exposure energy of $1.5\;J/cm^2$. This result suggests that the latter polymer with larger flexibility compared to the former polymer is more effective for the photoalignment.

Preparation of Silver Nanoparticles Using AgNO3 Precursor as Carrier for Olefin/Paraffin Separation and the Effect Analysis of NO3- (올레핀/파라핀 분리용 운반체로서 AgNO3 전구체를 활용한 은 나노입자 제조 및 NO3-의 효과 분석)

  • kim, Minsu;Kang, Sang Wook
    • Membrane Journal
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    • v.28 no.4
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    • pp.265-270
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    • 2018
  • In previous studies, a poly(ethylene oxide)(PEO)/Ag nanoparicles (AgNPs)(precursor $AgBF_4$)/p-benzoquinone (p-BQ) composite membrane was prepared for olefin/paraffin separation and the performance of this composite membrane was maintained at a selectivity of 10 and a permeability of 15 GPU. However, since the price of $AgBF_4$ precursor is high, this study used $AgNO_3$ as a precursor of Ag nanoparticles which is competitive in terms of price. As a result, it was observed that the separation performance was not obtained because the existing $NO_3{^-}$ could surround AgNPs. In this study, we fabricated PEO, poly(vinyl alcohol)(PVA), and polyether block amide-1657 (PEBAX-1657) polymer composite membrane using electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) for separation performance even when $AgNO_3$ was used as a precursor of Ag nanoparticles. As a result, it was analyzed that the performance was not observed regardless of the influence of the polymer and the electron acceptor, indicating that the anion of the precursor plays a crucial role in the separation performance.

($n^5$-Indenyl)trichlorotitanium-catalyzed Copolymerization of Styrene and Styrenic Macromonomer Carrying a Functional Group

  • Kim, Jungahn;Kim, Keon-Hyeong;Jin, Yong-Hyeon;Hyensoo Ryu;Soonjong Kwak;Kim, Kwang-Ung;Hwang, Sung-Sang;Jo, Won-Ho;Jho, Jae-Young
    • Macromolecular research
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    • v.8 no.1
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    • pp.44-52
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    • 2000
  • Styrenic macromonomers with/without a silyloxy-functional group were synthesizedvia chain-end functionalization using 4-vinylbenzyl chloride as a terminating agent insec-butyllithium-initiated polymerization of styrene. The yields were 92 mol% for the silyloxy group and 88 mol% for the styrenic unit. Crystalline polystyrene-g-amorphous polystyrenes were synthesized by (η$^{5}$ -indenyl)-trichlorotitanium ((Ind)TiCl$_3$)-catalyzed copolymerizations of the macromonomers with styrene in the presence of methyl-aluminoxane (MAO) in toluene at 4$0^{\circ}C$. The macromonomer having $\alpha$, $\alpha$'-bis (4-[tert-butyldimethylsilyl-oxy]phenyl) group was also utilized for the preparation of a precursor of hydroxyl-functionalized syndio-tactic polystyrene. The obtained polymers were characterized by a combination of$^1$H, $^{13}$ C NMR spectroscopic, size exclusion chromatographic, and differential scanning calorimetric analysis. The (Ind)TiCl$_3$-catalyzed copolymerization of styrene with the macromonomer carrying the silyloxy functional group was found to be an efficient method to modify syndiotactic polystyrene without a great loss of physica] property by controlling the feud ratio of the macromonomer.

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Errects of the Length of Carbon Fiber on the Wear Properties of Carbon/Carbon Composites (탄소/탄소 복합재료의 마모특성에 대한 탄소섬유 길이의 영향)

  • Ha, Hun-Seung;Kim, Dong-Kyu;Park, In-Seo;Im, Yeon-Su;Yun, Byung-Il
    • Korean Journal of Materials Research
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    • v.3 no.3
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    • pp.292-299
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    • 1993
  • In this paper the effects of the length of carbon fiber on the wear properties of carboni carbon composites were investigated. Carbon/carbon composites were fabricated by the liquid impregnation method using the resol-type phenolic resin as a matrix precursor and PAN-based, non-surface treated carbon fiber as a reinforcement. The measured values of the friction coefficient of carbon/carbon composites against AlSl 304 stainless steel ranged from 0.2 to 0.3 under the operating condition used in this study. The effect of the length of carbon fiber on the friction coefficient of carbon/carbon composites were not found. But, it was realized that the wear rate of carbon/carbon composites tends to increase, as the length of carbon fiber increases.

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Effect of Phosphorous-Based Flame Retardants on the Weight, Diameter, and Thermal Stability after Stabilization Processes of Rayon Fibers for Carbon Fibers (탄소섬유용 레이온섬유의 안정화공정 후 중량, 직경 및 열안정성에 미치는 인계 난연제의 영향)

  • Yoon Sung Bong;Cho Donghwan;Park Jong Kyoo
    • Polymer Korea
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    • v.29 no.2
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    • pp.211-215
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    • 2005
  • Stabilization process is absolutely necessary to convert the precursor fibers into chemically, physically, thermally and structurally stable carbon fibers. Especially, it is critically important for rayon fibers experiencing severe weight loss and thermal shrinkage occurring at the stabilization stage below $400^{\circ}C$. The stabilization of rayon fibers strongly depends not only on stabilization temperature but also on heating rate, chemical pre-treatment, atmosphere, and so on. In the present study, the weight loss, fiber diameter change occurred in the furnace during the stabilization process for rayon fibers produced with various heating rates and in the absence and presence of phosphorous-based flame retardants and the thermal stability of the stabilized fibers were investigated. The result indicates that the weight, diameter and thermal stability of the rayon fibers are significantly affected by the type and amount of the flame retardant used. It is also suggested that the pre-treatment of rayon fibers with a concentration lower than $3\;vol\%$ of phosphoric acid is most desirable for further carbonization process of stabilized rayon fibers.