• Title/Summary/Keyword: solvents

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Solvents for liquid phase epitaxial growth of silicon thin film for photovoltaics based on calculation (태양전지용 액상에피텍시얼 실리콘 박막성장을 위한 용매에 관한 계산)

  • ;Martin A. Green
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.5 no.1
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    • pp.37-43
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    • 1995
  • The proper choice of the solvent is a prerequisite for solution growth of silicon. In the present work, the temperature to dissolve at least 1 atomic% silicon was calculated in various molten solvents.

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Solvent Transport Characteristics of Glassy Polymers and its Analysis (유리고분자의 용매전달특성 및 그 해석)

  • 김덕준
    • Membrane Journal
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    • v.8 no.1
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    • pp.11-21
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    • 1998
  • The study on penetrant transport in glassy polymers has been actively pursued for decades because of its growing significance in polymer processing and related applications such as not only membranes, but corrosion protective coatings, microlithography, microelectronic fabrication, etc. In membranes application of polymeric materials, successful utilization requires understanding of how solvents penetrate, swell, and sometimes dissolve polymeric materials under various environmental conditions, as their permselecdve performance is significantly affected by it. The expose of polymer membranes to solvents may result in the structural failure due to mechanical softening, embrittlement or crazing.

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Effect of Solvent on Some Excited States Processes of Mg- and Zn-Phthalocyanines$^\dag$

  • Kim, Dong-Ho
    • Bulletin of the Korean Chemical Society
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    • v.7 no.6
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    • pp.416-421
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    • 1986
  • The solvent coordination effect on the excited state processes of Mg(II)- and Zn(II)-phthalocyanines has been described. The triplet state of these compounds decays with mixed first and second order kinetics or mainly second order kinetics depending on the solvents used. The first order component of the rate constants decrease along with the series, dimethylsulfoxide (5-coordinated), 1-chloronaphthalene (4-coordinated) and piperidine (6-coordinated), while the second order rate constant is dependent on the diffusion rate constant of the solvents. The excited state quenching by methylviologen or p-benzoquinone is discussed. And ion recombination rate constant is given.

Solvatochromic Effects and Hydrogen Bonding Interactions of 4-(4-Nitrophenylazo)-1-naphthol Derivatives

  • 신동명;권오악
    • Bulletin of the Korean Chemical Society
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    • v.16 no.7
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    • pp.574-577
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    • 1995
  • Solvatochromic effect and hydrogen bonding interaction of NPNOH, NPNO- and NPNOR were investigated. Electronic transition energies of the dyes were plotted against empirical solvent polarity parameters, Taft's π* and Reichardt's ET(30). Good correlations were observed when the excitation energies were plotted against the energy calculated by multiple linear regression method which was developed by Taft. There is an intrinsic difference between betaine for ET(30) polarity scale and the azoderivative, which is derived from the specific hydrogen bond incurred with probe molecules and solvents. The hydrogen bonding plays a very important role for stabilization of an excited state molecule by solvents especially when a solute possesses a negative charge as with NPNO-.

Cationic Polymerization of Electron-Donor Monomers by 1,1,2,2-Tetracyanocyclopropylstyrene, A New Electron-Acceptor

  • Ju-Yeon Lee;Sung-Ok Cho;A. B. Padias;H. K. Hall, Jr.
    • Bulletin of the Korean Chemical Society
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    • v.12 no.3
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    • pp.271-273
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    • 1991
  • Poly (N-vinylcarbazole) was obtained spontaneously by 1,1,2,2-tetracyanocyclopropylstyrene(1) in polar solvents such as dichloromethane and acetonitrile at room temperature. The polymerization reactions were faster in more polar solvent and were not proceeded in less polar solvents such as chloroform and diethyl ether. The formation of poly (N-vinylcarbazole) was explained by bond-forming initiation theory, in which the initiating species are zwitterionic tetramethylene intermediates.

Electronic excitation energy quenching of PPD by $CCl_4$ in different solvents

  • Biradar, D.S.;Thipperudrappa, J.;Hanagodimath, S.M.
    • Journal of Photoscience
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    • v.12 no.1
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    • pp.51-54
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    • 2005
  • The electronic excitationenergy quenching of 2, 5-diphenyl-1, 3, 4-oxadiazole (PPD) by Carbon tetrachloride ($CCl_4$) in different solvents viz, n-hexane, n-heptane, toluene, benzene, cyclohexane, 1, 4- dioxane has been carried out at room temperature to understand the role of quenching mechanism. The Stern-Volmer plots have been found to be linear. As probability of quenching per encounter 'p' is less than unity, and the activation energy for quenching '$E_a$' is greater than the activation energy of diffusion '$E_d$', it is inferred that the fluorescence quenching mechanism is not due to material diffusion alone.

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Rosin Microparticles as Drug Carriers: Influence of Various Solvents on the Formation of Particles and Sustained-release of Indomethacin

  • Lee Chang Moon;Lim Seung;Kim Gwang Yun;Kim Do Man;Kim Dong Woon;Lee Hyun Chul;Lee Ki Young
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.6
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    • pp.476-481
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    • 2004
  • The aim of this study was to formulate a sustained release system for indomethacin (IND) with rosin gum obtained from a pine tree. Rosin microparticles were prepared by a disper­sion and dialysis method without the addition of surfactant. In order to investigate the influence of solvents on the formation of colloidal microparitcles, various solvents like ethanol, DMF, DMAc, and acetone were used. The rosin microparticles containing IND were characterized by X­ray differactometry (XRD) and differential scanning calorimetry (DSC). The morphologies of rosin microparticles observed by scanning electron microscopy (SEM) were spherical. The solvents used to dissolve rosin significantly affected the drug content and drug release rate of IND. The release behaviors of IND from the rosin microparticles were dependent on the drug content and size of the particles. Rosin micorparticles with a higher drug content and of a larger particle size had a slower drug release rate. Also, the IND release rate from the rosin microparticles could be regulated by the rosin content in the microparticles. From these results, rosin microparticles have the potential of being used as a sustained release system of IND.

Synthesis and Characterization of Polyaniline doped with Ionic Liquid (이온성 액체로 도핑된 폴리아닐린의 합성 및 특성)

  • Hong, Jang-Hoo;Jo, Gyu Seong
    • Applied Chemistry for Engineering
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    • v.21 no.1
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    • pp.93-97
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    • 2010
  • Polyaniline doped with ionic liquid (1,3-dimethylimidazolium methylsulfate, I-DMS) soluble in polar solvents (NMP, DMSO, DMF, m-cresol etc.) were synthesized by nucleophilic addition. Solubilities of PAN/I-DMS powder in polar solvents were observed in the range of 3~6 wt%/vol., respectively. The electrical conductivities of PAN/I-DMS films appeared in the range of $10^{-2}{\sim}7S/cm$. Polyaniline doped with I-DMS (PAN/I-DMS) showed improved thermal stability and conductivity compared to that of HCl doped polyaniline (PAN/HCl) and dimethylsulfate (DMS) doped polyaniline (PAN/DMS) upon heat treatment at $160^{\circ}C$. These improved conductivity and solubility in organic polar solvents was explained with the interactions between the polar sulfonate group and polar solvents.

Clean Analysis Not to Use Harmful Solvent for TLC Identification Test of the Herbal Medicine (생약의 확인시험법에 대한 유해용매 대체시험법 설정)

  • Kim, Ji-Yeon;Park, Ju-Young;Shim, Young-Hoon;Cho, Chang-Hee;Lee, Jong-Hwa;Lee, Dong-Jin;Kim, Bo-Joon;Kim, Dong-Sup;Seong, Rack-Seon;Kim, Jong-Hwan;Lim, Sook;Shin, Jin-Seon;Jang, Seung-Yeup
    • Korean Journal of Pharmacognosy
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    • v.41 no.2
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    • pp.136-140
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    • 2010
  • This study was carried out to utilize non-toxic solvents instead of harmful solvents for the TLC(Thin Layer Chromatography) identification test of herbal medicines. It is recommended not to use harmful solvent such as chloroform at a viewpoint of clean analysis. In this study, we revised the identification test of 10 items in the Korea Pharmacopoeia(KP) and the Korean Herbal Pharmacopoeia(KHP) such as Cornus officinalis S. containing the harmful solvents on the developing solvent and established identification test that is utilized non-toxic solvents by HPTLC(High Performance Thin Layer Chromatography).