http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Single-walled carbon nanotubes directly-grown from orientated carbon nanorings
Tomohiro Tojo,Ryoji Inada,Yoji Sakurai,Yoong Ahm Kim 한국탄소학회 2018 Carbon Letters Vol.27 No.-
Surfactant-wrapped separation methods of metallic and semiconducting single-walled carbon nanotubes(SWCNTs) can result in large changes in intrinsic physical and chemical properties due to electronic interactions between a nanotube and a surfactant. Our approach to synthesize SWCNTs with an electronic feature relied on utilizing carbon nanorings, [n] cycloparaphenylenes([n]CPPs), which are the fundamental unit of armchair type SWCNTs(a-SWCNTs) that possess a metallic feature without any surfactants. To obtain long tubular structures from [n]CPPs, the host-guest complexes formed with well-aligned [n]CPP hosts and various fullerene guests on a silicon substrate were pyrolyzed under an ethanol gas flow at a high temperature with focused-ultraviolet laser irradiation. The pyrolyzed [n]CPPs were observed to transform from nanorings to tubular structures with 1.5–1.7 nm diameters corresponding to the employed diameter of [n]CPPs. Our approach suggests that [n]CPPs are useful for structure-controlled synthesis of SWCNTs.
Tomohiro Tojo,Cheon Soo Kang,Takuya Hayashi,Yoong Ahm Kim 한국탄소학회 2018 Carbon Letters Vol.28 No.-
Linear carbon chains (LCCs) encapsulated inside the hollow cores of carbon nanotubes (CNTs) have been experimentally synthesized and structurally characterized by Raman spectroscopy and transmission electron microscopy. However, in terms of electronic conductivity, their transportation mechanism has not been investigated theoretically or experimentally. In this study, the density of states and quantum conductance spectra were simulated through density functional theory combined with the non-equilibrium Green function method. The encapsulated LCCs inside (5,5), (6,4), and (9,0) single-walled carbon nanotubes (SWCNTs) exhibited a drastic change from metallic to semiconducting or from semiconducting to metallic due to the strong charge transfer between them. On the other hand, the electronic change in the conductance value of LCCs encapsulated inside the (7,4) SWCNT were in good agreement with the superposition of the individual SWCNTs and the isolated LCCs owing to the weak charge transfer.
Lee, Kyoung Min,Kim, Hea Ji,Kang, Cheon-Soo,Tojo, Tomohiro,Chae, Ji Ae,Oh, Yuree,Cha, Min Chul,Yang, Kap Seung,Kim, Yoong Ahm,Kim, Hyungwoo The Royal Society of Chemistry 2019 Polymer chemistry Vol.10 No.7
<P>Porous polymer monoliths are of great importance as a multi-scale material in the fields of materials science and chemical engineering. Herein, we create compressible, microporous, composite monoliths that are capable of regulating macroscopic conductivity in response to external compressive force. The materials have been synthesized <I>via</I> a bottom-up approach and behave as sponge materials. The monolithic polymer networks could be prepared using various monomeric building blocks and further incorporated with carbon additives during condensation polymerization. Accordingly, physical properties, such as morphology, mechanical strength, and miscibility, were investigated. Taking advantage of microporosity of these frameworks, the carbon-containing composites were found to be fairly lightweight yet substantial, and non-conductive despite the presence of 10 wt% conductive carbon additives. However, the intrinsic compressibility of the networks significantly altered the resistivity of materials (<I>e.g.</I>, <I>ρ</I> < 10<SUP>2</SUP> Ω m) when the density of the materials increased following the application of an external force, which is comparable to doped silicon or other clays. As a proof of concept, we used the composite material as a switch for an electrical circuit. Therefore, we were able to repeatedly turn on and off a light-emitting diode in the circuit by hand.</P>