• Macromolecular Research
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• 제16권7호
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• pp.644-650
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• 2008

This study examined the effect of nanoclays on the shape memory behavior of polyurethane (PU) in fibrous form. A cation was introduced into the PU molecules to disperse the organo-nanoclay (MMT) into poly($\varepsilon$-caprolactone) (PCL)-based PU (PCL-PU). The MMT/PCL-PU nanocomposites were then spun into fibers through melt-processing. The shape memory performance of the spun fibers was examined using a variety of thermo-mechanical tests including a new method to determine the transition temperature of shape memory polymers. The MMTs showed an improved the fixity strain rate of the MMT /PCL- PU fibers but a slight decrease in their recovery strain rate. This was explained by the limited movement of PU molecules due to the presence of nanoclays. The shape memory performance of the MMT/PCL-PU fibers was not enhanced significantly by the nanoclays. However, their recovery power was improved significantly up to a strain of approximately 50%.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3057-3060
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• 2009

Ionic palladium(II) complex, [($Me_4en)Pd(L)]_2(ClO_4)_4\;(Me_4$en = N,N,N',N'-tetramethylethylenediamine; L = bis-(4-(4-pyridylcarboxyl)phenyl)methane), allows to form a monodisperse submicrosphere without any template or additive. Surface-perchlorates on the submicrosphere have been exchanged by anionic pH indicators such as thymol blue, bromothymol blue, and bromocresol green. The ionic and amphiphilic properties of the palladium(II) complex appear to be primarily associated with the formation and easy surface-anion exchange of submicrosphere. The surface-anion exchange through the electrostatic interaction is a very good tool for the surface-modification. The color of the pH indicator-exchanged submicrospheres is very sensitive to pH and Hg$^{2+}$ cation, and thus they are promising to submicrospherical indicators.

• Bulletin of the Korean Chemical Society
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• 제20권10호
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• pp.1129-1135
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• 1999

Free energy perturbation and molecular dynamics simulations were carried out to investigate the relative binding affinities of [17] ketonand (1) toward alkali metal cations in methanol. The binding affinities of 1 toward the alkali metal cations were calculated to be in the order Li+ > Na+ > K+ > Rb+ > Cs+, whereas our recent theoretically predicted and experimentally observed binding affinities for [18]starand (2) were in the order K+ > Rb+ > Cs+ > Na+ > Li+. The extremely different affinities of 1 and 2 toward smaller cations, Li + and Na+ , were explained in terms of the differences in their ability to change the conformation to accommodate cations of different sizes. The carbonyl groups constituting the central cavity of 1 can reorganize to form a cavity with the optimal M+ -O distance, even for the smallest Li+, without imposing serious strain on 1. The highest affinity of 1 for Li+ was predominantly due to the highest Coulombic attraction between the smallest Li+ and the carbonyl oxygens of 1.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.159-162
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• 2021

The fragmentation pattern of four hindered phenol antioxidants was investigated using ammonium and lithium ions as the additives for ionization. Due to different binding geometries and interactions, they underwent different characteristic fragmentation reactions providing useful complementary information for structural analysis of hindered phenol antioxidants. Ammonium ion adducts were fragmented successively until all t-butyl groups were lost in the form of isobutylene and allowed the estimation of the number of t-butyl groups present in the molecule. Lithium ion adducts produced fragment ions from major backbone cleavage, on the other hand, which provide more crucial information for the identification of detailed backbone structure.

• 대한지하수환경학회지
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• 제4권2호
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• pp.103-108
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• 1997

본 연구에서는 일련의 회분식 실험을 통하여 소수성 유기오염물질로 오염된 토양에 혼합 계면활성제를 이용한 토양세척기법을 적용함에 있어서 필요한 기본 운전조건을 도출하고자 하였다. 혼합 계면활성제는 계면활성제 각각이 단독으로 존재할 때와는 상이한 분자 집합구조를 형성하게 되므로 세척효율을 향상시키기 위하여 적용하였다. 세척효율에 크게 영향을 미치는 요소인 혼합되는 계면활성제의 종류, 혼합비, 총 적용농도 등을 변경하며 적용하였다. 대상 오염물질로는 n-dodecane을 사용하였으며, 토양은 서울 녹천역 부근의 야산에서 채취된 토양중 #4체(4.75 mm) 통과 토양만을 사용하였으며, pH는 4.4, 유기물질함량은 1.6%(중량비), 양이온 치환능력(cation exchange capacity, CEC)은 4.08 meq/100 g이었다. Polyoxyethylene oleyl ester계를 중심으로 제조된 혼합 계면활성제의 세척력을 조사한 결과, OA-5와 OA-l4가 1:1 (중량비)로 혼합된 5% 용액이 86%의 세척효율을 보였다. 또한 음이온계 계면활성제인 SDS와 OA-5가 1:1(중량비)로 혼합된 4% 용액을 적용한 결과 최고 95%의 세척효율을 보였다.

• 공업화학
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• 제1권1호
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• pp.23-29
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• 1990

급속동결 전처리가 유기이온교환 수지의 분쇄에 미치는 효과를 연구하였다. 습윤상태의 이온교환 수지를 고체탄산 또는 액체질소를 이용하여 급속동결하면 이온교환 수지의 내부구조가 물리적으로 파괴되며 일단 파괴된 수지는 다시 실온이 되어도 원래의 상태로 회복되지 않음을 발견하였다. 따라서 급속동결한 수지는 실온에서도 분쇄가 매우 용이하며 이 효과는 양이온교환 수지가 음이온교환 수지에 비하여 더 크게 나타났다. 아울러 음이온교환 수지의 경우, 급속동결 전처리 효과 뿐만 아니라 이온종류 역시 분쇄에 큰 영향을 미침을 관찰할 수 있었다.

• 대한화학회지
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• 제41권11호
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• pp.612-638
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• 1997

모나자이트광 속에 포함되어 있는 회토류 원소들을 이온교환수지를 이용하여 분리 회수 하는 방법에 관해 연구하였다. 이온교환수지로는 양이온교환수지와 음이온교환수지를 사용하고, 용리액으로는 EDTA, DTPA, IMDA, Ln-EDTA 용액을 사용하였으며, 양이온교환수지는 retaining 이온 곧 $H^+, Zn^{2+}, Fe^{3+}, Al^{3+}, Cu^{2+}, NH^+_4$으로 치환된 수지를 사용하였다. 음이온교환수지는 EDTA로 치환된 수지에 Ln-EDTA착물을 흡착시켜 분리하였다. 여러 가지 회토류 원소 중에서 선택적으로 한 원소만 분리하기 위해 용리액으로 Ln-EDTA를 사용하였으며, 수지통의 크기 변화와 여러 가지 용리형태의 메카니즘, 그리고 다량의 회토류 원소를 분리 회수하는 방법 등에 관해 연구하였다.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2325-2332
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• 2012

A series $[C_3Omim]$[X] of imidazolium cation-based ILs, with ether functional group on the alkyl side-chain have been synthesized and structure of the materials were confirmed by various techniques like $^1H$, $^{13}C$ NMR spectroscopy, MS-ESI, FTIR spectroscopy and EA. More specifically, the influence of changing the anion with same cation is carried out. The absorption capacity of $CO_2$ for ILs were evaluated at 30 and $50^{\circ}C$ at ambient pressure (0-1.6 bar). Ether functionalized ILs shows significantly high absorption capacity for $CO_2$. In general, the $CO_2$ absorption capacity of ILs increased with a rise in pressure and decreased when temperature was raised. The obtained results showed that absorption capacity reached about 0.9 mol $CO_2$ per mol of IL at $30^{\circ}C$. The most probable mechanism of interaction of $CO_2$ with ILs were investigated using FTIR spectroscopy, $^{13}C$ NMR spectroscopy and result shows that the absorption of $CO_2$ in ether functionalized ILs is a chemical process. The $CO_2$ absorption results and detailed study indicates the predominance of 1:1 mechanism, where the $CO_2$ reacts with one IL to form a carbamic acid. The $CO_2$ absorption capacity of ILs for different anions follows the trend: $BF_4$ < DCA < $PF_6$ < TfO < $Tf_2N$. Moreover, the as-synthesized ILs is selective, thermally stable, long life operational and can be recycled at a temperature of $70^{\circ}C$ or under vacuum and can be used repeatedly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.723-726
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• 2005

The two major obstacles in the application of IPMC to flapping actuators operated in the air are solvent loss and actuation force. In this paper, solvent loss of various IPMCs made of Nafion$^{TM}$117(183$\mu$m thickness) has been experimentally investigated to find out the best combination of cation and solvent for minimal solvent loss in IPMCs and higher actuation force. For this purpose. experiments for the internal solvent loss measurement of IMPCs have been conducted for various combinations of cation and solvent. From the experiments, it was found that heavy water showed improvement in the operating time up to more than two minutes. in the tip force measurement of IPMCs, it was found that smaller and thicker IPMCs produced larger tip forces. However, the shorter IPMCs generated reduced actuation displacements and created flapping motion with decreased natural frequency. For the design of flapping device actuated by 5mm wide, 10mm long, 0.2mm thick IPMCs were used in the stacked form. Since the actuation force is a few gram-force, we stacked five IPMCs to improve actuation force. To amply the actuation force, rack-and-pin ion type hinge was used for the flapping device and insect (Cicadidae) wing was attached to the stacked IPMC actuator. In the flapping test, the device could generate flapping angle of 15$^{\circ}$ at 6Hz excitation by 2.5 voltage square wave input.

• 멤브레인
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• 제13권3호
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• pp.143-153
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• 2003

본 연구에서는 양이온교환막 표면에 형성된 바이폴라 계면이 물분해 현상에 미치는 영향을 조사하였다. 실험결과, 전기투석 중 막표면에 형성된 고정화된 바이폴라 계면이 심각한 물분해를 유발함을 알 수 있었다. 특히, 고정화된 바이폴라 계면은 다가 양이온이 전해질로 이용되는 전기투석 시스템에서 양이온교환막 표면에 쉽게 형성됨을 알 수 있었다. 낮은 용해도적 상수를 갖는 다가 양이온들은 급격한 물분해를 유발하였는데 이는 이들이 막표면에서 쉽게 수산화물의 형태로 침적되며 따라서 수소-친화 그룹과 수산화-친화 그룹으로 구성된 바이폴라 계면이 막-용액 계면에 형성됨을 알 수 있었다. 따라서 물분해는 막 표면의 금속수산화물 층과 막의 고정전하 그룹간에 발생되는 강한 전기장에 의해 크게 활성화됨을 알수 있다. 또한 이와 유사하게 분자량이 큰 유기 상대이온들이 막표면에 누적되는 경우에도 고정화된 바이폴라 계면이 형성되어 한계전류밀도 이상에서 심각한 물분해를 유발하였다. 따라서 전기투석의 고전류 운전시 효율 향상을 위해서는 막표면에 유발되는 고정화된 바이폴라 계면의 형성을 억제하는 것이 매우 중요함을 알 수 있다.