• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.80-80
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• 2006

As the size scale of features continue to shrink in devices, the use of self-assembly, i.e. a "bottom up" approach, for device fabrication becomes increasingly important. Yet, simple self-assembly alone will not be sufficient to meet the increasing demands place on the registry of structures, particularly nanostructured materials. Several criteria are key in the rapid advancement and technology transfer for self-assembling systems. Specifically, the assembly processes must be compatible with current $^{\circ}{\infty}top\;down^{\circ}{\pm}$ approaches, where standard photolithographic processes are used for device fabrication. Secondly, simple routes must be available to induce long-range order, in either two or three dimensions, in a rapid, robust and reliable manner. Thirdly, the in-plane orientation and, therefore, ordering of the structures, must be susceptible to a biasing by an external, macroscopic means in at least one, if not two directions, so that individual elements can be accessed in a reliable manner. Block copolymers, specifically block copolymers having a cylindrical microdomain morphology, are one such material that satisfy many, if not all, of the criteria that will be necessary for device fabrication. Here, we discuss several routes by which these versatile materials can be used to produce arrays of nanoscopic elements that have high aspect ratios (ideal for templating and scaffolding), that exhibit long-range order, that give access to multiple length scale structuring, and that are amenable to being biased by macroscopic features placed on a surface.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2333-2337
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• 2007

Nanoporous TiO2 and ZrO2 thin films were spin-coated using a surfactant-templated approach from Pluronic P123 (EO20PO70EO20) as the templating agent, titanium alkoxide (Ti(OC4H9)4) as the inorganic precursor, and butanol as a the solvent. The control of the electronic structure of TiO2 is crucial for its various applications. We found that the band gap of the hybrid nanoporous thin films can be easily tuned by adding an acetylacetonestabilized Zr(OC4H9)4 precursor to the precursor solution of Ti(OC4H9)4. Pores with a diameter of 5 nm-10 nm were randomly dispersed and partially connected to each other inside the films. TiO2 and ZrO2 thin films have an anatase structure and tetragonal structure, respectively, while the TiO2-ZrO2 hybrid film exhibited no crystallinity. The refractive index was significantly changed by varying the atomic ratio of titanium to zirconium. The band gap for the nanoporous TiO2 was estimated to 3.43 eV and that for the TiO2-ZrO2 hybrid film was 3.61 eV.

• 한국표면공학회지
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• 제40권1호
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• pp.16-22
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• 2007

Recently, mesoporous metallic materials are becoming more and more important in various applications like catalysts, electrochemical detectors, batteries, and fuel cells because of their high surface area. Among the various methods for manufacturing mesoporous structure, surfactant templating method followed by electroplating has been tried in this study. A mesoporous metallic film was prepared by electrodeposition from electroplating solution mixed with surfactant template. Nonionic type lyotropic liquid crystalline surfactant, Brij56, and nickel acetate based solution were selected as a template material and electroplating solution, respectively. To determine the content of surfactant forming a hexagonal column structure, the phase diagram of electroplating solution and surfactant mixture has been exploited by polarized optical microscopy equipped with heating and cooling stage. Nickel films were electroplated on Cu foil by stepwise potential input method to alleviate the concentration polarization occurred during the electroplating process. TEM and XRD analyses were performed to characterize the size and shape of mesostructures in manufactured nickel films, and electrochemical characterization was also carried out using cyclic voltammetry.

• 공업화학
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• 제20권5호
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• pp.527-531
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• 2009

전구체로서 bis(triethoxy silyl) benzene (BTEB), 구조유도체로서 dodecyl trimethyl ammonium bromide (DTMA)를 사용하여 periodic mesoporous organosilicas (PMO) 합성하였다. PMO를 XRD, TEM, 그리고 NMR로 확인한 결과 육각 벌집형태의 메조포러스한 물질임을 확인하였다. 합성한 PMO에 polyethylene oxide (PEO)를 삽입하여, DSC와 XRD로 확인한 결과 고분자가 PMO에 삽입되는 과정에서 고분자의 결정성 용융 온도가 감소하다가 결국 사라짐을 확인하였다. 이러한 결과는 고분자 사슬이 PMO의 기공에 삽입되었다는 것이며, 삽입된 고분자 사슬은 PMO의 골격구조에 의하여 제한 받아서 비결정성 형태의 구조를 지니고 있음을 보여주고 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.24-25
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• 2011

Molecular self-assembly has several advantages over other nanofabrication methods. Molecular building blocks ensure ultrafine pattern precision, parallel structure formation allows for mass production and a variety of three-dimensional structures are available for fabricating complex structures. Nevertheless, the molecular interaction for self-assembly generally relies on weak forces such as van der Waals force, hydrogen bonding, or hydrophobic interaction. Due to the weak interaction, the structure formation is usually slow and the degree of ordering is low in a self-assembled structure. To promote self-assembly, directed assembly methods employing prepatterned substrates or external fields have been developed and gathered a great deal of technological attention as a next generation nanofabrication process. In this presentation a variety of directed assembly methods for soft nanomaterials including block copolymers, peptides and carbon nanomaterials will be introduced. Block copolymers are representative self-assembling materials extensively utilized in nanofabrication. In contrast to colloid assembly or anodized metal oxides, various shapes of nanostructures, including lines or interconnected networks, can be generated with a precise tunability over their shape and size. Applying prepatterned substrates$^{1,2}$ or introducing thickness modulation$^3$ to block copolymer thin films allowed for the control over the orientational and positional orderings of self-assembled structures. The nanofabrication processes for metals, semiconductors$^4$, carbon nanotubes$^{5,6}$, and graphene$^{6,7}$ templating block copolymer self-assembly will be presented.

• Carbon letters
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• 제18권
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• pp.24-29
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• 2016

High pollutant-loading capacities (up to 319 times its own weight) are achieved by three-dimensional (3D) macroporous, slightly reduced graphene oxide (srGO) sorbents, which are prepared through ice-templating and consecutive thermal reduction. The reduction of the srGO is readily controlled by heating time under a mild condition (at 1 10⁻² Torr and 200℃). The saturated sorption capacity of the hydrophilic srGO sorbent (thermally reduced for 1 h) could not be improved further even though the samples were reduced for 10 h to achieve the hydrophobic surface. The large meso- and macroporosity of the srGO sorbent, which is achieved by removing the residual water and the hydroxyl groups, is crucial for achieving the enhanced capacity. In particular, a systematic study on absorption parameters indicates that the open porosity of the 3D srGO sorbents significantly contributes to the physical loading of oils and organic solvents on the hydrophilic surface. Therefore, this study provides insight into the absorption behavior of highly macroporous graphene-based macrostructures and hence paves the way to development of promising next-generation sorbents for removal of oils and organic solvent pollutants.

• 폴리머
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• 제39권1호
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• pp.151-156
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• 2015

본 연구에서는 디메틸실록산과 벤젠으로 구성된 단량체 용액에 방향성 결정화를 두 차례 진행하여 새로운 기공 구조를 제작하였다. 우선 첫 번째 용매의 방향성 결정화를 통해 벌집 형태의 기공 구조를 제작하였다. 상기 용액을 다시 담지한 뒤, 다시 방향성 결정화를 진행하게 되면 벌집 형태의 기공 구조 내에 또 다른 기공 구조가 혼재되어 있는 새로운 구조를 얻을 수 있었다. 반복된 방향성 결정화로 제조된 다공성 소재는, 한번의 방향성 결정화로 제조된 소재보다 압입탄성계수와 압입경도가 높았으며, 높은 농도의 용액으로 두 번째 방향성 결정화가 진행된 경우에 최대 증가치(압입탄성계수: 2140% 증가, 압입경도: 2330% 증가)를 얻을 수 있었다. 반면, 두 번째 방향성 결정화가 진행된 경우, 첫 번째 방향성 결정화만 진행된 경우보다 기공률과 접촉각은 감소하였으며, 높은 농도의 용액으로 두 번째 방향성 결정화가 진행된 경우 이들 물성의 최대 감소(기공률: 21% 감소, 접촉각: 36% 감소)를 관찰할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.64.2-64.2
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• 2010

In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• Elastomers and Composites
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• 제49권4호
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• pp.330-335
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• 2014

Niobium pentoxide ($Nb_2O_5$) 나노입자는 niobium (V) chloride 와 pluronic F108NF를 전구체와 주형제로 사용하여 합성하였다. $Nb_2O_5$-graphene나노복합체는 아르곤 가스 분위기 전기로 조건에서 2시간 동안 $700^{\circ}C$로 가열하였다. 시료의 결정화도, 결정형태, 광촉매 분해 반응성은 X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy를 사용하여 측정하였다. $Nb_2O_5$-graphene나노복합체는 254 nm의 자외선 조건에서 유기염료 광촉매 분해 반응의 광촉매로 사용되었다. 유기염료는 methylene blue (MB), methyl orange (MO), rhodamine B (RhB), brilliant green (BG)이 사용되었다. 또한 $Nb_2O_5$-graphene나노복합체를 사용하여 유기염료 광촉매 분해 반응의 반응 속도를 결정하였다.