• Korean Membrane Journal
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• 제9권1호
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• pp.43-51
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• 2007

This paper describes the preparation and characterization of two kinds of fluorinated polybenzimidazole (PBI)s which can be potentially used for phosphoric acid-doped, high-temperature polymer electrolyte membrane fuel cells. Two kinds of perfluorocyclobutane (PFCB)-containing monomers were prepared via following synthetic steps; after fluoroalkylation of methyl 3-(hydroxy) benzoate and methyl 4-(hydroxy) benzoate with 1,2-dibromotetrafluoroethane and subsequent Zn-mediated dehalogenation, these compounds were cyclodimerized at $200^{\circ}C$ affording the ester-terminated monomers containing PFCB ether groups. The synthesized intermediates and monomers were characterized using FT-IR, $^1H-NMR,\;^{19}F-NMR$, and mass spectroscopy. The fluorinated PBIs were then successfully prepared through the solution polycondensation of the monomers and 3,3'-diaminobenzidine in polyphosphoric acid. Compared with traditional PBI, the glass transition temperatures of the fluorinated PBIs were obtained at $262^{\circ}C\;and\;269^{\circ}C$ which are lower than that of PBI and their initial degradation temperatures were still high over $400^{\circ}C$ under nitrogen. The fluorinated PBIs showed higher d-spacing values and improved solubility in several organic solvents as well as phosphoric acid, which confirmed they could be good candidates for the high temperature fuel cell membranes.

• Macromolecular Research
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• 제11권6호
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• pp.431-436
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• 2003

A new photoconducting polymer, diphenyl hydrazone-substituted polysiloxane, was successfully synthesized by the hydrosilylation method and characterized by FT-IR, $^1$H-NMR, and $^{29}$ Si-NMR spectroscopy. The glass transition temperature (T$_{g}$) of the polysiloxane having pendant diphenyl hydrazone was ca. 62 $^{\circ}C$, which enabled a component of a low-T$_{g}$ photorefractive material to be prepared without the addition of any plasticizers. This polysiloxane, with 1 wt% of $C_{60}$ dopant, showed a high photoconductivity (2.8 ${\times}$ 10$^{-12}$ S/cm at 70 V/${\mu}{\textrm}{m}$) at 633 nm, which is necessary for fast build-up of the space-charge field. A photorefractive composite was prepared by adding a nonlinear optical chromophore, 2-{3-[2-(dibutylamino)-1-ethenyl]-5,5-dimethyl-2-cyclohexenylidene} malononitrile, into the photoconducting polysiloxane together with $C_{60}$ . This composite shows a large orientation birefringence ($\Delta$n = 2.6 ${\times}$ 10$^{-3}$ at 50 V/${\mu}{\textrm}{m}$) and a high diffraction efficiency of 81 % at an electric field of 40 V /${\mu}{\textrm}{m}$.textrm}{m}$.EX>.

• 폴리머
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• 제39권2호
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• pp.225-234
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• 2015

In this study, we proposed to synthesize thermally stable, soluble and conjugated Schiff base polymer (SbP). For this reason, a specific molecule namely 4,4'-thiodiphenol which has sulfur and oxygen bridge in its structure was used to synthesize bi-functional monomers. Bi-functional amino and carbonyl monomers namely 4,4'-[thio-bis(4,1-phenyleneoxy)] dianiline (DIA) and 4,4'-[thiobis(4,1-phenyleneoxy)]dibenzaldehyde (DIB) were prepared from the elimination reaction of 4,4'-thiodiphenol with 4-iodonitrobenzene and 4-iodobenzaldehyde, respectively. The structures of products were confirmed by elemental analysis, FTIR, $^1H$ NMR and $^{13}C$ NMR techniques. The molecular weight distribution parameters of SbP were determined by size exclusion chromatography (SEC). The synthesized SbP was characterized by solubility tests, TG-DTA and DSC. Also, conductivity values of SbP and SbP-iodine complex were determined from their solid conductivity measurements. The conductivity measurements of doped and undoped SbP were carried out by Keithley 2400 electrometer at room temperature and atmospheric pressure, which were calculated via four-point probe technique. When iodine was used as a doping agent, the conductivity of SbP was observed to be increased. Optical band gap ($E_g$) of SbP was also calculated by using UV-Vis spectroscopy. It should be stressed that SbP was a semiconductor which had a potential in electronic and optoelectronic applications, with fairly low band gap. SbP was found to be thermally stable up to $300^{\circ}C$. The char of SbP was observed 29.86% at $1000^{\circ}C$.

• 한국추진공학회지
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• 제20권2호
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• pp.31-38
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• 2016

세계적으로 사용 중인 대부분의 추진물질들은 연소 시 메탄가스, 이산화탄소 등의 환경유해 물질을 다량 발생시킨다. 본 연구에서는 이러한 문제를 개선하기 위해 에너지 가소제로 사용 가능한 고질소 화합물인 트리아졸 계열의 4,5-bis(azidomethyl)-methyl-1,2,3-triazole(DAMTR)의 합성공정을 확립하였다. 또한, 분광분석(NMR, IR)을 통해 DAMTR의 구조를 분석하였고, 유리전이온도, 녹는점, 분해온도, 밀도, 점도, 충격감도, 점도, 휘발성 등의 물리적 특성을 측정하였다. 그리고 Gaussian 09와 EXPLO5를 이용하여 생성열과 폭발 특성(폭압, 폭속) 등을 계산하였다.

• 한국응용과학기술학회지
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• 제31권1호
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• pp.1-6
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• 2014

Gemini type of cationic surfactant, namely ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide was synthesized and confirmed by FT-IR and $^1H$-NMR spectroscopy. Their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.01{\times}10^{-5}{\sim}4.99{\times}10^{-5}mol/L$. The Krafft point of the these surfactants were < $0^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1159-1164
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• 2012

A new colorimetric sensors containing thiourea (1-(4-nitrophenyl)-3-quinolin-6-ylthiourea; 1) and urea(1-(4-nitrophenyl)-3-quinolin-6-ylurea; 2) moieties for fluoride were designed and synthesized. These simple receptors were characterized their stoichiometry, and investigates the mechanism of their selectivity as anion receptors. The addition of tetrabutylammonium fluoride salts to the solution of receptors caused a dramatically and clearly observable color changes from colorless to yellow. To examine their application as anion receptors by UV-vis and $^1H$ NMR spectroscopy results revealed their higher selectivity for fluoride ion than other anions. The receptors and fluoride ion formed a 1:1 stoichiometry complex through strong hydrogen bonding interactions in the first step, followed by a process of deprotonation in presence of an excess of $F^-$ in DMSO solvent.

• 대한화학회지
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• 제65권2호
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• pp.113-120
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• 2021

New phenylthiophenechalcones,1-(biphenyl-4-yl)-3-(5-phenylthiophen-2-yl)prop-2-en-1-one (3a) and 3-(5-phenylthiophen-2-yl)-1-(4-(piperidin-1-yl) phenyl) prop-2-en-1-one (3b) were synthesized, next, their treatment with thiosemicarbazide in ethanol afforded their pyrazoline derivatives (4a) and (4b), respectively. The molecular structures of the synthesized compounds were confirmed via elemental analysis, FT-IR, 1H, 13C NMR and mass spectroscopy. The geometrical elucidation of four suggested conformers has been studied for these compounds. DFT calculations have been performed to study the stability and the structural parameters of the predicted conformers and revealed that orientation of the biphenyl and the phenylthiophene moieties affect the stability of the estimated conformers of the synthesized chalcones and pyrazoline. Moreover, two reaction mechanisms have been proposed to illustrate the reaction products and the DFT calculations have been used to confirm the reaction mechanism of the pyrazoline compounds.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.181-185
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• 2003

Callus and suspension cultures derived from leaf explants of Plumbago rosea were established on Murashige and Skoog's medium containing 1 mg/L IAA, 0.5 mg/L NAA and 0.3 mg/L BAP. Callus cultures were tested for their growth and accumulation of plumbagin, a naphthoquinone and was identified by $^1H$ NMR and electron ionization mass spectroscopy. While auxins (not 2,4-D) influenced growth and plumbagin accumulation, cytokinins did not influence them much. Increasing concentrations of IAA in presence of NAA and BAP increased plumbagin in suspensions only up to 1 mg/L. Growth of callus was optimum (8.3 g DCW/I) at a hormonal combination of 1.5 mg/L IAA, 0.5 mg/L NAA and 0.3 mg/L BAP, but high plumbagin accumulation (4.9 mg/g DCW) was recorded at 1.0 mg/L IAA plus 0.3 mg/L BAP. Since instability in growth and secondary metabolite accumulation was noticed, several cell lines/clumps of callus were screened for plumbagin accumulation by visual and analytical methods. Biomass and accumulation of plumbagin showed a negative correlation in several cell lines. But one cell line showed stability both in terms of biomass and plumbagin accumulation over a period of 6 months.

• 한국결정성장학회지
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• 제28권1호
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• pp.44-50
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• 2018

The improved high-performance Fe-based perovskite-type oxides ($La_{0.7}Sr_{0.3}M_xFe_{1-x}O_3$, M = Cu, Cr, Ni) were synthesized by a citrate method and characterized by SEM, EDS, XRD and NMR spectroscopy analyses. The characterization analyses revealed that the stoichiometric amounts of lattice oxygen were existed in all of perovskite samples except for a nickel-doped perovskite. Fe-based perovskites exhibited a surprising result for ortho-para $H_2$ spin conversion reaction, indicating two orders of magnitude higher conversions and conversion rates than commercial $Fe_2O_3$. It was considered that this conversion difference might be attributed to the presence of oxygen vacancies in Fe-based perovskites prepared in this study.

• 한국응용과학기술학회지
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• 제28권2호
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• pp.140-145
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• 2011

Cationic gemini-surfactant, namely 1,4-butane-bis(N-alkanoyloxyethyl-N,Ndimethyl)-diammonium bromide was synthesized and their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. The synthesized product was confirmed by FT-IR and $^1H-NMR$ spectroscopy. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.1{\times}10^{-5}{\sim}5.4{\times}10^{-5}$ mol/L. The Krafft point of the these surfactants were <0~$10.7^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, 1,4-butane-bis(N-lauroyloxyethyl-N,N-dimethyl)- diammonium bromide, CGL 14-4-14 has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.