• 약학회지
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• 제31권2호
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• pp.45-51
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• 1987

Methyl orange(MO) and cetyltrimethylammonium bromide(CTA) were mixed and added to 10ml of the buffer solution and then the solution was shaken for 5 minutes. The maximum absorption wavelength of the reaction product was 419nm. Dichloromethane was the best extracting solvent among the several organic solvents and the most suitable pH range was 2~8. When the CTA-MO calibration curve was made in the best experimental condition, the Lambert-Beer's law was obeyed in the range of CTA concentration of $1.5\times$$10^{-5}$~1.0$\times$$10^{-4}M$ by UV spectrophotometer. This method was possible to determine quaternary ammonium salts in the pharmaceutical preparations.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.327-327
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• 2006

Methyl glycidyl ether has been polymerized in a controlled fashion at low temperature in toluene using the combination of tetraoctyl ammonium bromide and triisobutyl aluminum. Poly(glycidyl methyl ether)s with molar masses ranging from 3 000 to about 90 000 g/mol and narrow polydispersities (<1.2) were prepared and the dependence of their solubility and LCST in water as a function on their molar masses investigated.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.164-166
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• 1988

7-Dithiocarboxy-3-phenyl-5,6-dihydro imidazo[2,1-b]thiazolium-betaine (2) was prepared by treatment of 3-phenyl-5,6-dihydro imidazo[2,1-b]thiazole (1) with carbon disulfide in acetone at room temperature. On the reaction of 2 with para-substituted phenacyl bromides (4) having the electron withdrawing property by virtue of (+) resonance (R) < (-) inductive (I) or (-) resonance (R), (-) inductive (I) effect, ring transformation product p-substituted-2-[2-[7-(p-substituted benzoyl)-5-thioxo-2,3-dihydro-1H-imidazo[1,2-c] thiazol-1-yl]-2-phenylvinylthio] acetophenone (6) was obtained; however, when R is electron donating grops with (+) resonance (R) > (-) inductive (I) effect the quarternary ammonium salt 7-(p-substituted phenyl) carbonyl methyl-3-phenyl-5,6-dihydro imidazo [2,1-b] thiazolium bromide (8) is formed. The reaction of 2 with unsubstituted-phenacyl bromide (R = H), on the other hand, gives 6a and 8a to the similar ratio, respectively.

• Bulletin of the Korean Chemical Society
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• 제10권2호
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• pp.172-177
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• 1989

Stereoselective solvolyses of optically active activated esters in the aggregate system of optically active polymeric surfactants containing imidazole and benzene moieties were performed. The catalyst polymers employed were copolymers of N-methacryloyl-L-histidine methyl ester (MHis) with N,N-dimethyl-N-hexadecyl-N-[10-(p-methacryloylo xyphenoxycarbonyl)-decyl]ammonium bromide(DEMAB). In the solvolyses of N-carbobenzoxy-D- and L-phenylalanine p-nitrophenyl esters (D-NBP and L-NBP) by polymeric catalysts, copoly(MHis-DEMAB) exhibited not only increased catalytic activity but also enhanced enantioselectivity as the mole ${\%}$ of surfactant monomers in the copolymers increased. The polymeric catalysts showed noticeable enantioselective solvolyses toward D- and L-NBP of the substrates employed. As the reaction temperature was lowered for the solvolyses of D- and L-NBP with the catalyst polymer containing 3.5 mole ${\%}$ of MHis, the increased reaction rate and enhanced enantioselectivity were observed. The coaggregative systems of the polymer and monomeric surfactants were also investigated. In the case of coaggregate system consisted of 70 mole ${\%}$ of cetyldimethylethylammonium bromide with polymeric catalyst showed maximum enantioselective catalysis, viz., $k_{cat}(L)/k_{cat}(D)$ = 2.85. The catalyst polymers in the sonicated solvolytic solutions were confirmed to form large aggregate structure by electron microscopic observation.

• 대한화학회지
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• 제54권4호
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• pp.437-442
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• 2010

수용액 속에서 $NaHSO_4$, TBAB (phase transfer catalyst), ionic liquid (IL) (1-butyl-3-methyl imidazolium hydrogen sulphate [bmim]$HSO_4$)를 사용하여, formalin, ${\beta}$-naphthol, aromatic amines을 반응시켜서 대응하는 2,3-dihydro-2-phenyl-1Hnaphtho-[1,2-e] [1,3] oxazine 유도체를 합성할 수 있는 보다 친환경적이고, 수율이 좋고, 크로마토그래피 분리 방법을 사용하지 않는 합성 방법을 개발하였다.

• 한국재료학회지
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• 제27권6호
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• pp.307-311
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• 2017

Organometal halide perovskite materials, due to the tunability of their electronic and optical properties by control of composition and structure, have taken a position of significant importance in optoelectronic applications such as photovoltaic and lighting devices. Despite numerous studies on the structure - property relationship, however, practical application of these materials in electronic and optical devices is still limited by their processability during fabrication. Achieving nano-sized perovskite particles embedded in a polymer matrix with high loading density and outstanding photoluminescence performance is challenging. Here, we demonstrate that the careful control of nanoparticle formation and growth in the presence of poly(methyl methacrylate) results in perovskite nanoparticle - polymer nanocomposites with very good dispersion and photoluminescence. Furthermore, this approach is found to prevent further growth of perovskite nanoparticles, and thus results in a more uniform film, which enables fabrication using the perovskite nanoparticles.

• 폴리머
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• 제34권4호
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• pp.313-320
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• 2010

신나메이트기를 갖는 새로운 자기 경화형 감습성 고분자 및 고분자형 앵커제로 사용하기 위하여 [2-[(methacryloyloxy) ethyl]dimethyl]propyl ammonium bromide(MEPAB), methyl methacrylate(MMA), 3-(trimethoxysilyl) propyl methacrylate(TMSPM) 및 2-(cinnamoyloxy)ethyl methacrylate(CEMA)의 공중합체들 을 합성하였다. 광가교성 공중합체들로서 MEPAB/MMA/TMSPM/CEMA＝70/20/0/10의 조성을 갖는 공중합체는 감습성 전해질 고분자로서, 그리고 50/0/20/30과 0/0/50/50 조성은 고분자형 부착제로 사용하였다. 이들 광가교형 고분자 실란커플링 처리제의 전극 표면과 부착 특성을 비교하기 위하여 3-(triethoxysilyl)propyl cinnamate(TESPC)도 표면 부착을 위한 표면처리제로서 사용하였다. 표면처리제는 전극의 기재 표면 위에 공유결합을 통하여 광가교성 신나 메이트 박막을 형성시킬 수 있었으며 센서에 UV가 조사되었을 때 전해질 고분자가 [2$\pi$+2$\pi$] 환화반응을 이용한 가교반응으로 기재에 부착되었다. 이렇게 고분자 표면처리제 및 TESPC로 처리된 센서들은 24시간 물에 침적시켰을 때 60~85%의 저항 증가가 생겼으며 이것은 상대습도 변화로서 2.25~3.15%RH에 해당하였다. 또한, -0.2%RH 이하의 양호한 히스테리시스, 90초의 응답 및 회복속도, 그리고 80 $^{\circ}C$ 및 90%RH의 고온 고습에서 매우 좋은 신뢰성을 보여주었다.

• 한국표면공학회지
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• 제51권1호
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• pp.79-85
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• 2018

We systematically investigated the optical properties of sub-micron sized methylammonium lead tribromide ($CH_3NH_3PbBr_3$) cubes in the range of 100 to 700 nm, which were prepared by a surfactant-free precipitation method. We found that despite the strong absorbance, their photoluminescence quantum yield (PLQY) is very low as 0.009~0.011 % for whole range of sizes. Surfactant-free synthesis approach results in nanocubes that has no surface passivating reagents (e.g. surfactants) on their surface. As-prepared particles contain a large number of surface defects that may cause the low PLQY. The role of the surface defects were investigated in their photoluminescence decay process, which can be correlated with the particle size. Larger particles are characterized by a slower decay rate compared to smaller particles due to a large number of surface defects in the smaller particles that trap more excitons in the fluorescence decay process. These experimental results provide new insights into the fundamental relationship between surface state and optical properties.