• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1763-1770
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• 2013

A series of the block copolymers were successfully synthesized from post-sulfonated hydrophilic and hydrophobic macromers via three-step copolymerization. The degrees of sulfonation (DS) of the copolymers (10%, 30%, or 50%) were controlled by changing the molar ratio of the hydrophilic and hydrophobic parts. The resulting block copolymers were characterized by $^1H$ NMR and other technologies. The membranes were successfully cast using dimethyl sulfoxide (DMSO) solution at $100^{\circ}C$. The copolymers were characterized to confirm chemical structure by $^1H$ NMR and FT-IR. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated that all sulfonated block copolymers exhibited good thermal stability with an initial weight loss at temperatures above $240^{\circ}C$. The membranes showed acceptable ion exchange capacity (IEC) and water uptake values in accordance with DS. The maximum proton conductivity was 184 mS $cm^{-1}$ in block copolymer-50 at $60^{\circ}C$ and 100% relative humidity, while the conductivity of Nifion-115 was 160 mS $cm^{-1}$ under the same measurement conditions. AFM images of the block copolymer membranes showed well separated the hydrophilic and hydrophobic domains. From the observed results it is that the prepared block membranes can be considered as suitable polymer electrolyte membranes for the application of polymer electrolyte membrane fuel cells (PEMFC).

• 공업화학
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• 제9권3호
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• pp.342-347
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• 1998

경량성의 전도성복합수지는 전도성고분자인 폴리피롤과 폴리티오펜이 다공성의 가교폴리스티렌의 내부에 분산되어 전도성네트워크를 형성시킴으로 제조된다. 높은 다공성과 친유성의 특성을 갖는 호스트고분자는 고농축에멀션중합방법을 이용하여 합성하고 전도성복합수지는 이 호스트고분자를 이용하여 이단계 함침방법으로 제조한다. $FeCl_3$을 개시제와 혼입체로 사용하여 제조한 폴리피롤복합수지의 전기전도도는 0.82 S/cm이며, $FeCl_3$-아세토니트릴을 개시제로 사용하여 제조한 폴리티오펜복합수지는 전기전도도가 6.05 S/cm에 이른다. 전도성복합수지의 전기전도도는 사용된 산화제 용매와 초기산화제와 단량체 몰비율에 크게 영향을 받는다. 전자현미경조사에 의하면 전도성고분자가 다공성 호스트고분자 내부벽에 필림을 형성한다. 폴리피롤소재복합수지와 폴리티오펜소재복합수지의 전기차단효율은 2.0 GHz에서 각각 15.2dB와 22.5dB였다. 20K-300K의온도범위에서 저항의 온도의존성에 대한 실험결과에 의하면 전도성복합수지는 반도체특성을 보이고 전기전도기구는 전형적인 VRH모델을 따른다.

• Macromolecular Research
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• 제12권2호
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• 한국세라믹학회지
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• 제45권5호
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• pp.290-296
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• 2008

$AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structures which have been reported as proton conductors over $600^{\circ}C$ were studied. The $AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structure is known to be more easily synthesized and has better stability than normal $ABO_3$ perovskite structure. And it is stable at about $800^{\circ}C$ in the $CO_2$ atmosphere, whereas the $BaCeO_3$ perovskite is easily decomposed into carbonate. In addition, this $AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structure could simply produce oxygen vacancies within their structure not by introducing additional doping oxides but by just controling the molar ratio of $B'^{+3}$ and $B"^{+5}$ metal ions in the B site. Hence it is easy to design the structure which shows highly sensitive electrical conductivity to humidity. In this study, the single phase boundary of $BaR_{0.5+x}Ta_{0.5-x}O_{3-{\delta}}$(R = rare earth) complex perovskite structures and it's phase stability were investigated with changes in composition, x. And the humidity dependance of electrical conductivity at different $P_{H2O}$ conditions was investigated.

• 한국환경농학회지
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• 제14권3호
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• pp.263-271
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• 1995

중금속에 의한 토양오염을 화학적으로 평가하기 위한 일환으로 토양을 중금속으로 오염시킨 후 토양용액을 추출하여 pH, 이온강도, 이온농도, 화합물형태 변화를 분석했다. 토양이 Cu와 Cd에 의해 오염될수록 토양용액의 이온강도는 증가했다. 이런 변화는 Cd보다 Cu에 의해 더 컸다. 토양용액 중의 Cu와 Cd의 농도는 가한 양(量)에 비해 소량으로 존재했으나 처리량에 비례하여 금속의 농도는 증가했다. 토양용액 중의 Cd의 농도는 Cu보다 훨씬 높았다. 토양용액 중의 Ca, Mg, K의 농도는 중금속에 의해 증가되었으나 주로 free ion상태로 존재했으며 화합물형태는 Cu나 Cd의 처리에 의해 변화되지 않았다. 토양용액 중 중금속이온의 화합물의 변화 경향은 Cu와 Cd이 달랐다. Cu의 경우 토성과 pH에 의해 영향을 받았는데 pH가 낮은 SiCL 및 SL 토양에서는 free $Cu^{2+}$가 95 molar % 이상으로 주된 화합물형태이었고 pH가 높은 LS토양의 경우 free $Cu^{2+}$과 Cu-hydroxide이 주된 화합물형태로 Cu처리량에 따라 이들 화학종의 molar %는 변화되었다. Cd의 경우 free $Cd^{2+}$과 Cd-chloride 화합물이 주된 화합물형태이었고 Cd처리량이 증가함에 따라 $Cd^{2+}$는 감소한 반면 Cd-chloride 화합물 형성은 증가했다. 중금속에 의한 토양용액의 pH감소, 중금속의 흡착에 따른 양이온의 일시적인 증가, 중금속의 화합물 변화들은 식물영양적 측면에서 볼 때 식물에 불리한 변화로 간주되며, 중금속의 생물유효성과 독성을 평가하는 자료로 활용될 수 있을 것이다.

• 한국환경보건학회지
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• 제20권3호
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• pp.31-38
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• 1994

Dithiocarbamates containing polar groups which give very water soluble metal complexes were prepared from the reaction of carbon disulfide with diamines. The compounds have been characterized by elemental analysis, molar conductivity, and spectroscopic results. Dithiocarbamate and its complex were soluble in water. N, N-Dimethylammoniumpropylenedithiocarbamate(A) is clearly effective as inhibition of cis-platinum nephrotoxicity in rats. From the result of A rescue after cis-dichlorodiammineplatinum(II) treatment, it is suggested that dithiocarbamate removes platinum(II) coordinated to -SH groups bound to protein of kidney tubule cells by the reaction of platinum(II) with dithiocarbamate injected. A is effective as antidots for acute cadmium poisoning in Bacillus subtills. Growth of Bacillus subtills may be accelerated by A ligand dissociated from cadmium (II)-A complex.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1757-1763
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• 2004

A new series of nickel(II), cobalt(II)/(III) and copper(II) complexes of 14, 15 and 16-membered of macrocyclic ligands have been prepared and characterized by elemental analyses, IR, UV-VIS and $^1H-NMR$ spectra, magnetic susceptibilities, conductivities, DTA and ESR measurements. Molar conductances in DMF solution indicate that, the complexes are nonelectrolytes except (9-12) complexes. The electronic spectra show that, all complexes are square planar or distorted octahedral geometry. The ESR spectra of solid complexes (4), (8) and (11) show square planar of axial type symmetry $(d_{x2-y2})$ with considerable covalent bond character. However, complex (12) shows a spectrum of octahedral geometry with $d_{z2}$ ground state. Complex (12) shows exploitation in reducing the amount of electron adducts formed in DNA during irradiation with low radiation products.

• 대한화학회지
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• 제55권6호
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• pp.926-931
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• 2011

A series of complexes of the type [$ML_2Cl_2$], where L=2-(o-anisylidene-2'-imino) amino benzimidazole (AIAB) and 2-(furfurylidene imino) amino benzimidazole (FIAB), M=Cu(II), Co(II), Ni(II) and Zn(II), have been synthesized and characterized on the basis of elemental analysis, thermal analysis, molar conductivity, magnetic moment, electronic, infrared, $^1H$-NMR spectral studies. The results are in consistent with bidentate chelation of ligand with azomethine nitrogen and ring nitrogen donors. All these Schiff bases and their complexes have also been screened for their antibacterial (Bacillus subtilis, Bacillus stearothermophilus, Escherichia coli and Salmonella typhi) and antifungal activities (Aspergillus niger and Aspergillus flavus).

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1583-1587
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• 2009

The four dentate $N_2O_2$ Schiff base ligand of bis(2-hydroxyacetophenone)-1,2-propanediimine (BHAPN) and its manganese (III) complex were synthesized and identified by microanalysis, spectral data ($^1H$ NMR, MS, FT-IR and UV-Visible) and molar conductivity measurement. The mild and efficient homogeneous oxidative decarboxylation of some carboxylic acids by catalytic amount of this manganese (III) complex, using tetrabutylamonium periodate as a mild oxidant in chloroform at room temperature is reported. The catalyst used in this study showed good activity for the decarboxylation of the titled compounds.

• 한국수소및신에너지학회논문집
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• 제22권1호
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• pp.60-68
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• 2011

[ $ZrO_2-TiO_2$ ]binary oxides with various Zr:Ti molar ratios were prepared by sol-gel method and Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were fabricated for proton exchange membrane fuel cells (PEMFCs) at high temperature and low humidity. Water uptake, Ion exchange capacity (IEC), and proton conductivity of Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were characterized and these composite membranes were tested in a single cell at $120^{\circ}C$ with various relative humidity (R.H.) conditions. The obtained results were compared with the unmodified membranes (Nafion$^{(R)}$ 112 and Recast Nafion$^{(R)}$). A Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membrane with 1:3 of Zr:Ti molar ratio showed the highest performance. The performance showed 500 mW/$cm^2$ (0.499V) at $120^{\circ}C$, 50% R. H., and 2 atm.