• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.4165-4168
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• 2012

Magnetic fluorescent silica nanotubes were fabricated using reverse micro-emulsions coupled with conventional sol-gel methods. Anodic aluminum oxide templates were used to separate spatially the magnetic and the fluorescent moieties on individual nanotubes and so prevent quenching of the fluorescence. C18 and fluorescent layers were deposited sequentially on silica. Magnetism was then obtained by the introduction of pre-made magnetic nanoparticles inside the nanotubes. The photo- and chemical stabilities of nanotubes were demonstrated through dye release and photobleaching tests. The produced nanotubes did not show fluorescence quenching upon the addition of the nanoparticles, an advantage over conventional spherical fluorescent magnetic nanoparticles. High photostability of nanotubes, magnetism and biocompatiblily make them potentially useful in bioanalysis.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1427-1429
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• 2010

• 한국응용과학기술학회지
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• 제28권2호
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• pp.185-195
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• 2011

Carbon nanotube(CNT) plays an essential role in various fields of nano based science and technology. Recently, silica coated CNT composites are interested because they are useful for the optical, magnetical, and catalytic applications. In this report, carboxyl groups were introduced on the MWCNT using nitric acid. In order to maximize the silica encapsulation efficiency, carboxyl groups of MWCNT reacted with a silane coupling agent were used to prepare silica coated MWCNT. Due to their strong interaction between modified MWCNT and TEOS. Silica layer with a controllable thickness was achieved. Silica coated MWCNT were further utilized as the template for the synthesis of hollow silica nanotubes after $800^{\circ}C$ calcination.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.275-278
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• 1999

We have grown vertically aligned carbon nanotubes in a large area of Co-Ni codeposited Si substrates by the thermal CVD using $C_2$H$_2$gas. Since the discovery of carbon nanotubes, Synthesis of carbon nanotubes for mass production has been achieved by several methods such as laser vaporization, arc discharge, and pyrolysis. In particular, growth of vertically aligned nanotubes is of technological importance for applications to FED. Recently, vertically aligned carbon nanotubes have been grown on glass by PECVD. Aligned carbon nanotubes can be also grown on mesoporous silica and Fe patterned porous silicon using CVD. Despite such breakthroughs in the growth, the growth mechanism of the alignment are still far from being clearly understood. Furthermore, FED has not been clearly demonstrated yet at a practical level. Here, we demonstrate that carbon nanotubes can be vertically aligned on catalyzed Si substrate when the domain density reaches a certain value. We suggest that steric hindrance between nanotubes at an initial stage of the growth forces nanotubes to align vertically and then nanotubes are further grown by the cap growth mechanism.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권8호
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• pp.451-454
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• 2000

We have grown vertically aligned carbon nanotubes in a large area of Co-Ni codeposited Si substrates by the thermal CVD usign $C_2H_2$ gas. Since the discovery of carbon nanotubes, growth of carbon nanotubes has been achieved by several methods such as laser vaporization, arc discharge, and pyrolysis. In particular, growth of vertically aligned nanotubes is important to flat panel display applications. Recently, vertically aligned carbon nanotubes have been grown on glass by PECVD. Aligned carbon nanotubes can be also grown on mesoporous silica and Fe patterned porous silicon using CVD. In this paper, we demonstrate that carbon nanotubes can be vertically aligned on catalyzed Si substrate when the domain density of catalytic particles reaches a certain value. We suggest that steric hindrance between nanotubes at an initial stage of the growth forces nanotubes to align vertically and each nonotubes are grown in bundle.

• Composites Research
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• 제29권5호
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• pp.306-314
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• 2016

본 연구에서는 에폭시 복합재료의 기계적 물성을 향상시킴과 동시에 상대적 단점으로 지적될 수 있는 열안정성과 치수 안정성의 문제를 개선하고자 에폭시 복합재료를 다중벽 탄소나노튜브와 마이크로미터 크기의 실리카 입자로 강화하였다. 두 충전제는 별도의 개질 없이 전단혼합과 초음파기기만을 이용하는 물리적 방법으로 에폭시 수지 내에 분산시켰다. 두 충전제 함량에 따른 시편의 특성은 인장강도, 열팽창계수, 열전도도 측정을 통해 평가하였으며, 시편의 열 안정성을 보다 넓은 범위에서 고찰하기 위해 열팽창계수를 측정한 결과와 미시역학 모델을 이용해 계산한 결과를 비교하였다. 탄소나노튜브 함량 0.6 wt%에 실리카 함량 50 wt%로 강화된 하이브리드 복합재료 시편의 인장강도는 에폭시 복합재료 시편 대비 약 11%의 증가를 보여 가장 좋은 기계적 물성을 나타내었다. 열적 물성을 살펴보면 두 충전제의 함량에 따라 그 결과가 달라지는데, 특히 에폭시 수지 내에 실리카 함량이 증가할수록 열팽창계수는 약 36%까지 감소하였고, 이로 인해 시편의 열 변형이 줄어들면서 열 안정성도 개선되었다. 또한 실리카 함량 50 wt%로 강화된 에폭시 복합재료 시편의 열전도도는 약 72% 정도 증가하였다. 두 충전제로 강화된 하이브리드 복합재료 시편에서는 보다 향상된 기계적, 열적 물성을 확보할 수 있었다.

• 한국분말재료학회지
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• 제20권4호
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• pp.258-263
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• 2013

We examined various ball-milling parameters which affect the structural and morphological modification of multi-wall carbon nanotubes. In particular, the effect of milling mode and the use of different milling agents were examined. Friction milling mode induced more structural changes than impact milling mode except the use of dry ice as a milling agent. Wet milling was helpful for reducing more effectively the agglomeration of nanotubes than dry milling. The use of hard solid particles such as silica and alumina as milling agents resulted in an effective shortening of nanotubes, but often susceptible to the amorphization and the destruction of crystallinity.

• Bulletin of the Korean Chemical Society
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• 제25권1호
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• pp.63-68
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• 2004

Sugar-based gelator p-dodecanoyl-aminophenyl- ${\beta}$-D-aldopyranosides (1-3) have been shown to self-assemble in the presence of p-aminophenyl aldopyranosides. The hydrogel 1+4 showed the double-helical structure with 3-25 nm outer diameters, which is quite different from that of 1. The gel 2+5 revealed twisted ribbon structure with 30-50 nm in widths and a few micrometers of length whereas the gel 3+4 revealed the single and the bundled fiber structures. The difference in these gel supramolecular structures has successfully been transcribed into silica structures by sol-gel polymerization of tetraethoxysilane (TEOS), resulting in the doublehelical, the twisted-ribbon, the single and the multiple (lotus-shaped) hollow fiber structures. These results indicate that novel silica structures can be created by transcription of various superstructures formed in binary gels through the hydrogen-bonding interaction, and the amino group of the p-aminophenyl aldopyranosides acts as an efficient driving force to create novel silica nanotubes. Furthermore, electron energy-loss spectroscopy (ELLS) provided strong evidence for the inner hollow structure of the double-helical silica nanotube. This is a novel and successful example that a variety of new silica structures can be created using a library of carbohydrate gel fibers as their templates.

• 대한기계학회논문집A
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• 제40권12호
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• pp.1037-1046
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• 2016

본 연구에서는 기계적 물성을 개선함과 동시에 전기 절연성을 부여하기 위해 에폭시 수지에 탄소나노튜브와 실리카 입자를 혼입하여 하이브리드 복합재료를 제작하였다. 두 충전제의 함량을 변화시켜 제작한 시편으로 인장강도, 영률, 동적기계분석 그리고 전기 비저항을 측정하였으며, 이를 통해 기계적, 전기적 물성을 고찰하였다. 또한 하이브리드 복합재료 시편의 기계적 물성을 평가하고자 영률을 측정한 결과와 미시역학 모델을 이용해 계산한 결과를 비교하였다. 탄소나노튜브 함량 0.6 wt%와 실리카 함량 50 wt%를 첨가하여 제작한 하이브리드 복합재료 시편에서 인장강도 및 영률은 에폭시 복합재료 시편 대비 각각 약 11 %와 35 %의 증가를 보여 가장 높은 기계적 물성을 나타내었다. 에폭시 수지에 전도성 충전제인 탄소나노튜브를 분산시키면 전기 전도성이 향상되었으며, 여기에 절연성 충전제인 실리카를 추가로 혼입한 하이브리드 복합재료 시편에서는 개선된 기계적 물성과 더불어 전기 절연성을 증대시킬 수 있었다.

• Advances in nano research
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• 제16권5호
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• pp.459-472
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• 2024

Nanotechnology is a popular field in the construction industry due to its multiple functions. It mitigates CO₂ emissions and enhances the desirable properties of concrete by replacing small amounts of cement with supplements. This study assess the sustainability impact of using two different nanoparticles partially replacing the cement with 0.3%, 0.6%, 1.0% of nano silica (NS) and 0.03%, 0.045%, 0.06% of Multi-Walled Carbon Nanotubes (MWCNT) in the green concrete mix developement. Nano-sized fragments at the atomic scale tends to modify the properties of concrete. Concrete may increase its strength, durability by adding nanocomposite materials, which will decrease the amount of nano and micropores in structural parts. The strength of the structural elements can be greatly improved and allowing them to withstand higher loads and resist deformation. It improved durability properties by 64.8% in water absorption, 56.4% in acid attack, 78.1% in sulphate attack, and 53.4% in chloride attack. There was an improvement in compressive strength of 37% and split tensile strength of 90%. SEM, FTIR, and XRD investigations have used to look at the microstructural characteristics of nanoconcrete dictated the microstructure characteristics may be made more consistent and dense by adding nanocomposite materials.