1,3-Dipolar Cycloaddition of Azomethine Ylides to Alkenylboronates: Synthesis of Boronic Ester Substituted Pyrrolidine Derivatives and Asymmetric Approaches

Kyukwan Zong 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.5

TiO2-grafted multi-walled carbon nanotubes for dye-sensitized solar cells.

Hwang, Yun-Hwa,Kim, Hyunho,Zong, Kyukwan,Pyo, Myoungho American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.5

<P>Dye-Sensitized Solar Cells (DSSCs) comprised of TiO2 porous films with multi-walled carbon nanotubes (MWNT) were prepared at low temperature (150 degrees C). MWNT were incorporated to facilitate the fast electron transport resulting from metallic properties of carbon nanotubes. In order to enhance the effect of MWNT incorporation, TiO2-grafted MWNT (TiO2-MWNT) was synthesized which can increase the electron transport rate further due to proximity of TiO2 to MWNT The presence of TiO2 nanoparticles on the surface of MWNT was confirmed by electron microscopy and energy dispersive X-ray spectroscopy. As in the DSSCs prepared through high temperature sintering of photoanodes, the maximum content of MWNT incorporated into TiO2 was limited to 0.01 wt% relative to TiO2. TiO2 photoanodes including TiO2-grafted MWNT (TiO2-MWNT/P25) enhanced the cell efficiencies by ca. 28% and 14%, relative to TiO2 photoanodes without and with MWNT respectively, reaching the efficiency of 5.0%. Electrochemical impedance spectroscopy (EIS) was utilized to examine the effect of incorporation of TiO2 nanoparticles grafted to MWNT on the cell performance.</P>

An Efficient Synthesis of Thiophene/Pyrrole-Fused Crown Ethers Using Mitsunobu Reaction for Potential Application to Sensory Electroactive Polymers

Joongchul Kim,Daehyun Yoon,Sang Hee Lee,Seokbeom Ko,이연식,Kyukwan Zong* 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.11

Electrochemical synthesis and one step modification of PMProDot nanotubes and their enhanced electrochemical properties

Nguyen, Thao M.,Cho, Seungil,Varongchayakul, Nitinun,Yoon, Daehyun,Seog, Joonil,Zong, Kyukwan,Lee, Sang Bok The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.21

<P>Poly (3,4-(2-methylene)propylenedioxythiophene) (PMProDot) nanotubes were synthesized within the pores of polycarbonate and were further modified with styrene and vinylcarbazole by a one step electrochemical method through the methylene functional group. The enhanced electrochemical and electrochromic properties of composite nanotubes were investigated using FTIR, UV/Vis absorbance spectroscopy, and AFM.</P> <P>Graphic Abstract</P><P>Poly (3,4-(2-methylene)propylenedioxythiophene) (PMProDot) nanotubes have been synthesized and their facile and accelerated one-step modification with styrene and vinylcarbazole is reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc17152j'> </P>

담지체-CNT-PPy 혼합체의 발열체로서 응용과 PPy의 안정성 기여에 관한 연구

김윤진 ( Yoon Jin Kim ),이상모 ( Sang Mo Lee ),정세윤 ( Sae Yoon Jung ),윤대현 ( Dae Hyun Yoon ),정규관 ( Kyukwan Zong ) 전북대학교 과학교육연구소 2016 과학과 과학교육 논문지 Vol.41 No.2

본 연구에서는 좋은 전도도를 가진 탄소나노튜브 (CNT) 와 담지체로서 절연성 물질인 송진, 에폭시 (Epoxy), PC (Polycarbonate)를 적절한 비율로 섞어서 세 종류의 혼합체를 합성하였다. 그리고 이 들 혼합체에 다시 다양한 비율의 폴리피롤을 혼합하여 세 가지 물질로 구성된 새로운 복합소재를 합성하였다. 다양한 비율로 합성된 복합소재는 교류 (AC)와 직류 (DC)를 통과시켜 발열 소재로서의 특성이 분석되었다. 특히 폴리피롤이 함유되지 않은 혼합체와 함유된 혼합체를 비교 실험함으로서 폴리피롤의 역할이 중요한 요소로서 분석되었다. 실험 결과 모든 발열 혼합소재에서 폴리피롤이 함유된 혼합체가 발열체의 열적 안정성 향상에 크게 기여하는 것으로 나타났다. 대부분의 혼합체로 이루어진 소자 실험에서 PPy를 첨가할 경우 발열 온도가 크게 안정화 되는 결과를 가져왔다. 그러나 몇 개의 소자에서는 발열 온도는 안정화 되었지만 발열 효율이 조금 떨어지는 결과도 보였다. PC-CNT 혼합체로 구성된 발열 소자에서 PPy첨가는 발열 효율과 발열 온도의 안정성에 뛰어난 향상을 가져왔다. 약간의 PPy 첨가가 발열 소자의 효율과 안정성 향상에 크게 기여 한다는 것이 이 연구의 핵심이다. In this study, highly conducting carbon nanotube (CNT) was blended with insulating materials such as pine tree resin, epoxy, polycarbonate (PC) to prepare composites for electrical heating materials. Various ratio between CNT and insulating materials was carefully prepared to find the optimal conditions of the composites for electrical heating materials. The several devices containing each ratio were prepared and tested under AC or DC voltage. There is great difference with or without PPy in the composites in terms of heating performance and device stability. The devices comprised of PPy showed great stability of heating temperature in all examples. However, some examples showed lower heating temperature although heating temperature was much stabilized. In PC-CNT composites, addition of PPy into the composites brought excellent improvement of both heating temperature and device stability.

Synthesis and correlation between structure and photovoltaic performance of two-dimensional BDT-TPD polymers

Hong, Nam Jeong,Park, Hanok,Baek, Myoung-Jin,Lee, Soo-Hyoung,Jeong, Jo,Park, Jun Hui,Zong, Kyukwan Elsevier 2016 Organic Electronics Vol.35 No.-

<P><B>Abstract</B></P> <P>Four BDT-TPD polymers (<B>PA</B>–<B>PD</B>) were synthesized by modifying the alkylthienyl chains on BDT, placing spacer group between BDT and TPD, and installing extended conjugated side chains on the BDT of the polymer to investigate the correlation between structure and photovoltaic performance for these polymers. The molecular weight of <B>PA</B>–<B>PD</B> polymers ranged from the highest (<I>Mn</I> = 80 kDa for <B>PA</B>) to the lowest (<I>Mn</I> = 7.9 kDa for <B>PD</B>), and their decomposition temperatures at 5% weight loss were in the range 401–435 °C. PA, <B>PB</B>, and <B>PC</B> showed similar UV–vis absorption spectra; however, <B>PD</B> showed much broader absorption spectrum in the entire UV–vis region, because of the extended conjugated side chains. The HOMO levels of the polymers were −5.72, −5.63, −5.48, and −5.61 eV for <B>PA</B>, <B>PB</B>, <B>PC</B>, and <B>PD</B>, respectively, indicating very low-lying HOMO energy levels. The bandgaps of these polymers were calculated and found to be in the range 1.85–1.88 eV. The theoretical calculations clearly show that the torsional angles between the alkylthienyl group and BDT unit of the simplified dimer correlated to the π-orbital delocalization, suggesting that the HOMO π-electrons of vertically aligned conjugated side chains do not delocalize well in the polymers such as <B>PA</B>, <B>PB</B>, and <B>PC</B> bearing high torsional angles. The optimized weight ratios of the polymer to PC<SUB>61</SUB>BM were determined to be 1:1, 1:1.5, and 1:1 for <B>PA</B>, <B>PC</B>, and <B>PD</B>, respectively, and the average PCEs of the devices were 5.36%, 4.62%, and 2.74% for <B>PA</B>, <B>PC</B>, and <B>PD,</B> respectively, after optimization with 1,8-diiodooctane (DIO). A relatively small amount of DIO as an additive was necessary to reach the optimal PCEs of the devices, and the device incorporating PC needed only 0.5% DIO to obtain the best PCE. The AFM study reveals that the blend films after adding DIO showed much smooth morphologies, and the blend film of <B>PA</B> exhibited more crystalline property, as shown by the XRD analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Four PBDT-TPD polymers were designed and investigated by engineering alkyl group, spacer, and side chains. </LI> <LI> The polymer with branched alkyl chain shows higher PCEs due to better morphology and excellent <I>V</I> <SUB> <I>oc</I> </SUB> (>1 V). </LI> <LI> The polymer with a thiophene spacer shows higher <I>J</I> <SUB> <I>sc</I> </SUB> due to higher planarity of the polymer backbone. </LI> <LI> The polymer with vertically extended conjugated side chain exhibits broader range of absorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

탄소 동소체-황토 복합재료를 사용한 친환경 발열체 제작과 특성 분석

김소연 ( So Yun Kim ),최예윤 ( Ye Yoon Choi ),윤대현 ( Dae Hyun Yoon ),김효권 ( Hyokwon Kim ),정규관 ( Kyukwan Zong ) 전북대학교 과학교육연구소 2019 과학과 과학교육 논문지 Vol.44 No.1

본 연구는 친환경적 재료인 황토와 탄소 동소체인 탄소 나노튜브와 흑연을 혼합하여 발열체를 제작하고 발열 특성을 분석한 연구이다. 황토는 우리나라 대표적인 전통 건축 재료이다. 최근 황토가 친환경적이고 전자파를 차단하고 원적외선을 방출한다고 해서 전통 가옥의 벽과 실내의 온돌 바닥 재료로서 각광을 받고 있다. 특히 황토는 단열과 통풍성이 좋으며 겨울에는 따뜻하고 여름에는 시원한 특성을 가지고 있어 우리나라와 같은 사계절을 가진 나라에서 매우 적합한 건축 재료이다. 황토의 이런 장점을 살리고 매우 안정하고 인체에 무해한 전도성이 뛰어난 탄소 동소체인 흑연과 탄소 나노튜브의 장점을 살려 이 두 물질의 복합체를 합성하였다. 합성한 복합체를 사용하여 발열체를 제작하고 저항과 발열 효과를 측정하였다. 황토에 흑연을 넣어 만든 혼합체의 저항 값 측정에서 흑연 0.1g이 섞인 시료의 경우 저항 값이 크게 나타났지만 0.2g ~ 0.5g 까지의 시료의 경우 상대적으로 매우 낮은 저항 값을 보였다. 이들 시료는 평균 저항 값이 0.2kΩ ~ 4kΩ 까지의 매우 우수한 전기전도성을 나타내는 것을 알 수 있었다. 이로써 황토에 적정량의 흑연을 섞어 넣은 경우 매우 우수한 발열체로서의 기능을 가질 수 있음을 예측할 수 있었다. 실험을 통하여 탄소나노튜브보다는 흑연이 황토와 잘 혼합되는 성질을 보여 주었다. 그리고 동일 질량인 경우 탄소나노튜브가 흑연보다 더 높은 발열 효율을 보여 주었다. 따라서 황토와의 혼합성, 혼합 질량 비율, 경제성 등을 고려해 볼 때 흑연은 혼합성과 경제성에서 우수하고, 탄소나노튜브는 혼합 질량 비율에서 더 우수한 결과를 보여 주었다. This study centers around the construction of environmental friendly heating devices and characterization using the composites of carbon allotrope and loess. Loess is one of the most popular traditional construction materials. It has been extensively studied that loess is environmentally friendly construction material and very helpful to stop electrical radiation, also known to emit long wave length of infra-red. It also is excellent in permeating air and insulating, therefore the houses made of loess enjoy cool in summer and warm in winter. Meanwhile, carbon allostopes including graphite and carbon nanotube are very stable and highly conductive. From a variety of merits for loess and carbon allostropes, we designed and evaluated a heating device consisted of a composite of loess and carbon allotropes such as carbon nanotubes and graphite. the composites including up to 0.1 g of graphite showed very big electrical resistance but they displayed relatively low resistance in the range of 0.2-0.5g. These samples showed average of 0.2-4kΩ resistance and thus excellent electrical conductivities. Our study demonstrated that graphite showed superior miscibility with loess than carbon nanotube did. The composites including carbon nanotube displayed superior heating efficiencies than those including graphite did if the composites prepared from the same weight ratio between carbon allostrope and loess.

Investigations into inward positioned 3,3′-Dihexylditheinylbenzothiadiazole (DTBTh)-Benzodithiophene (BDT) based polymer solar cells by controlling molecular weight and alkyl side chain

Hong, Nam Jeong,Lee, You-Sun,Park, Jun Hui,Na, Seok-In,Choe, Joong Chul,Zong, Kyukwan ELSEVIER 2017 ORGANIC ELECTRONICS Vol.2017 No.42

Synthesis of 3,4-Dihydroxythiophene-2-carboxylate and Uses as Building Block for Efficient Synthesis of 3,4-Alkylenedioxythiophene (ADOT) Derivatives

Zong, Kyukwan Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.5