• Advances in nano research
• /
• 제2권2호
• /
• pp.121-133
• /
• 2014

Polymer nanocomposites are advanced nanomaterials which exhibit dramatic improvements in various mechanical, thermal and barrier properties as compared with the neat polymer. Polystyrene/ alumina nanocomposites were prepared by an ultrasound-assisted solution casting method at filler loadings ranging from 0.2 to 2% and also at different ultrasonic frequencies, viz. 58 kHz, 192/58 kHz, 430 kHz, 470 kHz and 1 MHz. The composites were subjected to mechanical property tests (tensile and impact tests) and cavitation erosion tests to study the enhancement in functional properties. Filler dispersion in the polymer matrix was observed by SEM analysis. The effect of frequency on filler dispersion in the matrix was studied by SEM analysis and functional property enhancement of the composite material. The composites prepared at dual (high/ low) frequency (192/58 kHz) were found to show better property enhancement at low filler loadings as compared with neat polymer and also with composites prepared without ultrasound, thus reinforcing the finding that ultrasound-assisted synthesis is a promising method for the synthesis of nanocomposites.

• 대한금속재료학회지
• /
• 제50권6호
• /
• pp.449-454
• /
• 2012

Nanopowder of FeAl and $Al_2O_3$ was synthesized from FeO and Al powders by high energy ball milling. Using the pulsed current activated sintering method, the nanocystalline $Al_2O_3$ reinforced FeAl composite was consolidated within two minutes from mechanically synthesized powders. The advantage of this process is that it allows very quick densification to near theoretical density and prohibits grain growth in nanostuctured materials. The grain size, sintering behavior and hardness of sintered $FeAl-Al_2O_3$ composite were investigated.

• 융합정보논문지
• /
• 제8권5호
• /
• pp.95-100
• /
• 2018

금속 산화물/그래핀 형태의 복합 나노소재는 높은 전기용량을 갖는 2차 전지의 전극용 소재 또는 고감도 가스 센서의 감지물질 등으로 활용되는 매우 유용한 기능성 소재이다. 본 논문에서는 열 화학기상증착(CVD, Chemical Vapor Deposition)으로 Cu Foil 위에 대면적으로 합성된 CVD 그래핀 및 고정렬 열분해 흑연(HOPG, Highly Oriented Pyrolytic Graphite)으로부터 기계적으로 박리된 그래핀 기판 위에 이산화바나듐($VO_2$) 나노구조물을 기상수송방법으로 직접 성장시키는 연구를 수행하였다. 연구결과 CVD 그래핀 기판의 경우, 그래핀 결정 경계에서 상대적으로 많이 존재하는 기능기들이 $VO_2$ 나노구조물에서 핵형성의 씨앗으로 작용하는 것이 확인되었다. 반면에 HOPG에서 기계적으로 박리된 그래핀 나노시트 표면에는 기능기가 균일하게 분포하기 때문에, 2차원과 3차원 형태로 $VO_2$ 나노구조물이 성장되었다. 이러한 연구결과는 고기능성 $VO_2$/그래핀 나노복합소재를 이용하여 높은 전기용량을 갖는 2차 전지 전극소재 및 고감도 가스 센서의 감지물질 합성에 유용하게 활용될 것으로 전망된다.

• Journal of Biosystems Engineering
• /
• 제40권4호
• /
• pp.373-393
• /
• 2015

Background: Cellulose is a ubiquitous, renewable and environmentally friendly biopolymer, which has high promise to fulfil the rising demand for sustainable and biocompatible materials. Particularly, the recent progress in the synthesis of highly crystalline cellulose-based nanoscale biomaterials, namely cellulose nanocrystals (CNCs), draws significant attention from many research communities, ranging from bioresource engineering, to materials science and engineering, to biological and biomedical engineering to bionanotechnology. The feasibility of harnessing CNCs' unique biophysicochemical properties has inspired their basic and applied research, offering much promise for new biomaterials with diverse advanced functionalities. Purpose: This review focuses on vital issues and topics on the recent advances in CNC-based biomaterials with potential, in particular, for bionanotechnology and biological and biomedical engineering. The challenges and limitations of CNC technology are discussed as well as potential strategies to overcome them, providing an essential source of information in the exploration of possible and futuristic applications of the CNC-based functional "green" nanomaterials. Conclusion: CNCs offer exciting possibilities for advanced "green" nanomaterials, driving innovative research and development in a wide range of fields, including biological and biomedical engineering.

• 전기화학회지
• /
• 제20권3호
• /
• pp.55-59
• /
• 2017

본 연구에서는 밀도범함수법 (DFT; Density Functional Theory) 기반의 제일원리 계산을 통해 페로브스카이트 $La_{0.5}Ca_{0.5}MnO_3$ (LCMO) 재료의 열전 특성에 미치는 열처리 효과를 조사하고 실험을 통해 확인해 보았다. 시뮬레이션을 통해 얻어진 열전 파워팩터 (PF; Power Factor) 값은 열처리 온도가 올라감에 따라 증가하는 현상을 보였으며, 1100 K에서 높은 PF 값 ($S^2{\sigma}=566{\mu}W/m{\cdot}K^2$)을 나타내었다. 해당 PF 열전 특성 값은 전기전도도 (Electrical Conductivity) 값의 향상보다는 지벡계수 (Seebeck Coefficient)의 향상에 더욱 우세한 영향을 받은 것으로 확인되었으며, 실험을 통해 각각의 열전 특성들에 미치는 영향성을 확인하였다. 수열합성법을 통해 합성된 $La_{0.5}Ca_{0.5}MnO_3$ 재료를 가지고 600K ~ 1100K의 온도 조건에서 열처리 공정을 진행했으며, 이후 XRD (X-ray Diffraction) 분석과 SEM (Scanning Electron Microscope) 분석을 통해 재료의 특성을 분석하였다. 결과적으로 사방정계 구조를 가지는 페로브스카이트 LCMO 재료는 900K 이상에서 16~19 nm의 작은 결정 크기를 가지고 있음을 확인했으며, 이를 통해 열처리 온도의 증가가 열전 주요 특성인 전기전도도와 지벡계수 값을 각각 향상시킬 수 있음을 밝혔다.

• Transactions on Electrical and Electronic Materials
• /
• 제17권3호
• /
• pp.168-171
• /
• 2016

There has been growing interest and rapid development in transparent electrode films, which are flexible and light and used in mobile, simple information, and electronic devices, and based on recent advancements in nano technology, information technology, and display technology. In particular, studies on developing such films with both high conductivity and high transmittance of visible rays are highly in demand for commercialization. In this study, transparent electrode films were developed for IT using micro patterns that show sheet resistance less than 10 Ω/□, adhesive strength more than 98%, and light transmittance more than 90%. The results of applying a surface emission gradient minimization (Honey Comb) technology to the films was the verification of the sheet resistance, adhesive strength, and light transmittance satisfying the target level of this study through Imprinting and Remolding processes.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.81-82
• /
• 2006

In this study, the applications of the block copolymer thin films are introduced. For this purpose, we first obtained cylindrical nanodomains in polystyrene-block-poly(methyl methacrylate) copolymer perpendicularly oriented to a substrate. Then, nanoporous templates were prepared after removing the PMMA nanodomains by UV treatment. By using electropolymerization, high density nanowire arrays of conducting polymer of poly(pyrrole) and poly( 3-hexyl thiopene) were obtained and their electric properties were measured. Also, these nanoporous thin films were found to be very useful for the separation of human Rhinovirus type 14 (HRV 14), major pathogen of a common cold in humans, from the buffer solution.

• Carbon letters
• /
• 제20권
• /
• pp.32-38
• /
• 2016

In this study, cellulose nanoplates (CNPs) were fabricated using cellulose nanocrystals obtained from commercial microcrystalline cellulose (MCC). Their pyrolysis behavior and the characteristics of the product carbonaceous materials were investigated. CNPs showed a relatively high char yield when compared with MCC due to sulfate functional groups introduced during the manufacturing process. In addition, pyrolyzed CNPs (CCNPs) showed more effective chemical activation behavior compared with MCC-induced carbonaceous materials. The activated CCNPs exhibited a microporous carbon structure with a high surface area of 1310.6 m²/g and numerous oxygen heteroatoms. The results of this study show the effects of morphology and the surface properties of cellulose-based nanomaterials on pyrolysis and the activation process.

• Elastomers and Composites
• /
• 제52권1호
• /
• pp.69-80
• /
• 2017

Conducting polymers and carbon nanomaterials offer a wide range of applications because of their unique soft conducting properties. Specifically, these conducting polymer-carbon nanocomposites have recently been utilized in bioengineering applications, partly because of their improved biocompatibility compared to conventional conducting materials such as metals and ceramics. Based on the assumption that these composites offer an important application potential as functional materials for biomedical devices or even as biomaterials, this review surveys the recent research trends on conducting polymers-carbon nanocomposites, focusing on bioengineering applications such as polyaniline (PANI), poly(3,4-ethylenedioxythiophene) or PEDOT, polypyrrole (Ppy), and carbon nanotubes and graphene.

• 한국전기전자재료학회논문지
• /
• 제27권10호
• /
• pp.635-641
• /
• 2014

In this study, the temperature control device was designed for the study in order to detect the output in frequency of temperature, and the study confirmed accurate temperature values treated systemically by using expanded A/D converting Technology. The control technology of functional sensor included the output error Detection. For the future study, it is necessary to implement a control device by building multiple circuits integrally with different types of sensors such as a automatically and intelligent notification function sensors.