• Macromolecular Research
• /
• 제15권1호
• /
• pp.51-58
• /
• 2007

The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

• 한국광물학회지
• /
• 제23권4호
• /
• pp.377-393
• /
• 2010

제3기 마이오세 화성쇄설성 퇴적층인 범곡리충군의 주요 구성 암층인 부석질 응회암의 흡착기능성 광물자원으로서의 자원잠재성을 평가하기 위하여 그 응용광물학적 특성 및 그 규제 요인에 대하여 해석하였다. 장기 지역 범곡리층군에서 주된 암상을 이루는 부석질 응회암은 속성변질되어 저품위 제올라이트 및 벤토나이트를 이룬다. 이들은 부석편의 존재로 인한 성분적 특수성에 기인하여 일부 광석들은 양이온치환 능력, 비표면적 및 산성의 pH 농도와 연관된 우수한 흡착기능성을 나타낸다. 이 흡착기능성 광물질에서 낮은 pH 농도를 유발하는 것은 주로 결정구조상 층간에 수소 이온을 갖는 H-스멕타이트의 존재에 의한 것으로 밝혀졌다. 이 H-스멕타이트는 층간 교환성 양이온으로서 수소 이온의 존재에 의해 결정구조상 불규칙성이 야기되어 엽편상의 결정 가장자리가 다소 말린 형태를 보이고, X-선회절 분석에서는 (001) 회절선을 비롯한 주요 기저 회절선들이 일반적인 Ca-유형의 스멕타이트에 비해 상대적으로 낮은 강도를 보이는 것이 특정이다, 이 H-스멕타이트의 원물질 해석과 광물 공생관계를 토대로 이 독특한 점토광물의 생성 모델을 제시하였다. 즉, 부석질 유리편이 속성과정 동안에 필연적으로 야기되는 수화 변질의 결과로 규산이 해리되면서 생성된 수소 이온에 의해 공극수의 pH가 감소되어 단백석이 생성됨으로써 스멕타이트의 생성을 조장한 것으로 여겨진다. 강한 산성을 유발하는 이같은 H-스멕타이트의 존재에 의해서 범곡리층군의 저품위 흡착기능성 광물자원의 산업적 효용도, 특히 산성백토나 상토 부문 등에서 긍정적으로 평가될 수 있을 것으로 여겨진다.

• 마이크로전자및패키징학회지
• /
• 제23권3호
• /
• pp.31-35
• /
• 2016

본 논문은 원자층 증착법을 이용해 증착된 YSZ 박막을 산화 세륨계 전해질 기반 고체 산화물 연료전지의 연료극 중간층으로 적용한 결과를 보여준다. $500^{\circ}C$ 이상의 고온에서는 산화 세륨계 전해질의 전기전도도가 상승하여 이를 전해질로 사용한 고체 산화물 연료전지의 개회로 전압이 하강하고 성능이 저하된다. 원자층 증착법을 이용해 연료극 측 전해질 표면에 증착된 YSZ 박막은 얇은 두께(60 nm)에도 불구하고 산화 세륨계 전해질 표면을 완벽하게 도포함으로써, 전해질을 관통하는 전자의 흐름을 막아 개회로 전압을 최대 20%까지 상승시켰다. 이를 통해 $500^{\circ}C$에서의 최대 전력 밀도는 52%가 상승하였다.

• 펄프종이기술
• /
• 제40권1호
• /
• pp.29-34
• /
• 2008

The charcoal has been used not only as fuel but also as human health care material since it was used. Charcoal's performances were generally investigated in aspects of energy efficiency and caloric values. This study was conducted in order to increase charcoal's application area and to develop functional paper. Five types of charcoal were used on a basis of gas absorption properties from previous study. Handsheets were made by two methods by internal loading and surface spray on interlayer. Strength properties of internal loading and interlayer spray handsheets were decreased as the charcoal loading increased. Ethylene gas absorption property was higher in both of oak's black charcoal and white charcoal than others. In terms of strength, 5-10% charcoal loading was efficient. Above 10% loading, a rate of strength decrease was higher than that of ethylene gas absorption rate. Formaldehyde absorption property was higher at both of oak's black charcoal and mixed charcoal than others. However, to guarantee enough charcoal loading should be higher than 95 $g/m^2$ for sufficient formaldehyde absorption.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.190-190
• /
• 2006

The approach used in present work allows achieving highly exfoliated state of layered silicate s through confinement of the charged nanobeads within the gallery of swollen pristine clay. The latter is principally promoted by ion exchange that involves polar functional groups on the surface of nanobeads and sodium cation in the interlayer gallery of layered silicates. Surface functionality of the nanobeads plays crucial role in establishment of strong interactions with silicate surface, and eventually, dispersion of individual silicate nanoplatelets.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.442-442
• /
• 2011

Electronic and magnetic properties of bilayer zigzag graphene nanoribbon (bZGNR) are studied using pseudopotential density functional method. The edge atoms in the top and bottom layers of bZGNR make a weak hybridization, which leads to electronic structures different from monolayer ZGNR. For asymmetric bZGNR, where the top and bottom layers have different widths, one edge is pinched by the interlayer bonding and the other sustains antiferromagnetic ordering. A small amount of charge transfer occurs from narrower to wider layer, producing spin-polarized electron and hole pockets. External electric field produces asymmetric energy-gap opening for each spin component, inducing half-metallicity in bZGNR.

• Nano
• /
• 제13권12호
• /
• pp.1850138.1-1850138.6
• /
• 2018

Two-dimensional (2D) or layered materials have a great potential for applications in energy storage, catalysis, optoelectronics and gas separation. Fabricating novel 2D or quasi-2D layered materials composed of relatively abundant and inexpensive atomic species is an important issue for practical usage in industry. Here, we suggest the layer-structured AlOOH (Boehmite) as a promising candidate for such applications. Boehmite is a well-known layer-structured material and a single-layer can be exfoliated from the bulk boehmite by breaking the interlayer hydrogen bonding. We study atomic and electronic band structures of both bulk and single-layer boehmite, and also obtain the single-layer exfoliation energy using first-principles calculations.

• 한국재료학회지
• /
• 제33권12호
• /
• pp.503-510
• /
• 2023

This comprehensive study delves into the intricate process of exfoliating and functionalizing boron nitride nanosheets (BNNSs) extracted from hexagonal boron nitride (h-BN), and meticulously explores their potential application within epoxy composites. The extensive research methodology encompasses a sequence of treatments involving hydrothermal and sonication processes aimed at augmenting the dispersion of BNNSs in solvents. Leveraging advanced analytical techniques such as Raman spectroscopy, X-ray diffraction, and FTIR spectroscopy, the study rigorously analyzes a spectrum of changes in the BNNS's properties, including layer count variations, interlayer interactions, crystal structure modifications, and the introduction of functional groups. The research also rigorously evaluates the impact of integrating BNNSs, specifically glycidyl methacrylate (GMA)-functionalized BNNSs, on the thermal conductivity of epoxy composites. The conclusive findings exhibit notable enhancements in thermal properties, predominantly attributed to the enhanced dispersion of fillers and enhanced interactions within the epoxy matrix. This pioneering work illuminates the wide potential of functionalized BNNSs for significantly enhancing the thermal conductivity of epoxy composites, paving the way for advanced materials engineering and practical applications.

• 한국초전도ㆍ저온공학회논문지
• /
• 제19권1호
• /
• pp.47-50
• /
• 2017

Carbon is proven to be very effective in pinning the magnetic vortices and improving the superconducting performance of $MgB_2$ at high fields. In this work, we have used polymethyl methacrylate (PMMA) polymer as a safe and cost effective carbon source. The effects of molecular weight of PMMA on crystal structure, microstructure as well as on superconducting properties of $MgB_2$ were studied. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for $MgB_2$ doped with different molecular weights of PMMA. This indicates that carbon could be substituted in the boron honeycomb layers without affecting the interlayer interactions. As compared to undoped $MgB_2$, substantial enhancement in $J_c(H)$ properties was obtained for PMMA-doped $MgB_2$ samples both at 5 K and 20 K. The enhancement could be attributed to the effective carbon substitution for boron and the refinement of crystallite size by PMMA doping.

• 한국진공학회지
• /
• 제15권4호
• /
• pp.360-366
• /
• 2006

0,25 ML의 산소원자가 흡착하여 이루는 O/Pd(100)-p($2{\times}2$) 표면의 원자구조를 밀도범함수 이론 계산을 통해 연구하였다, Pd(100) 표면의 fourfold hollow 위치가 가장 안정된 산소 흡착위치로 밝혀졌고 O-Pd 결합거리는 $2,15{\AA}$으로 계산되었다. 산소 흡착에 의해 Pd(100) 표면의 첫 번째 층간격 ($d_{12}$) 은 +0,8%의 팽창을 보이는데 이 계산결과는 +3,6%의 팽창을 보고 한 LEED 실험 결과와 차이를 보인다. 차이의 원인으로 시료 표변에 수소 불순물이 존재하였을 가능성을 고려하여 계산한 결과, O/Pd(100)-p($2{\times}2$)에 수소원자가 흡착할 때 $d_{12}$의 팽창이 유발됨을 확인하였다. 수소 흡착량에 따른 구조변화를 분석하여 LEED 시료 표변에 잔존할 것으로 예상되는 수소의 양을 약 0,3 ML로 추정하였다.