• Membrane Journal
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• v.20 no.1
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• pp.55-61
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• 2010

A diblock copolymer of polystyrene-b-poly(oxyethylene methacrylate) (PS-b-POEM) was synthesized via atom transfer radical polymerization (ATRP), as revealed by FT-IR spectroscopy. The self-assembled block copolymer membrane was prepared and used to template the growth of silver nanoparticles in the solid state by the introduction of $AgCF_3SO_3$ precursor and UV irradiation process. Transmission electron microscopy (TEM) and UV-visible spectroscopy confirmed the in situ formation of silver nanoparticles within the block copolymer membranes, and the size of nanoparticles were controlled by adjusting the moiety of hydrophilic POEM domains. PS-b-POEM block copolymer with a lower POEM content was effective in generating smaller size of metal nanoparticles.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.504-504
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• 2011

최근 디지털 프린팅 기술의 핵심기술로 떠오르고 있는 잉크젯 프린팅 기술은 최근 기존의 문서인쇄 뿐 아니라, 직물 인쇄, 태양전지 등의 다양한 반도체 소자 제조에 널리 활용되고 있으며, 점차 그 응용 분야를 넓혀가고 있다. 특히 thermal 방식의 잉크젯 피린팅 기술은 etching, thin film process, lithography등의 반도체 공정 기술을 이용하여 제작할 수 있기 때문에, 현재 잉크젯 프린팅 기술은 대부분 thermal 방식을 체택하고 있다. 이러한 thermal 잉크젯 프린팅 방법에서는 잉크를 토출시키기 위하여, 전기적 에너지를 열에너지로 전환하는 전자저항막층이 필수적으로 필요하게 되는데, 이러한 전자저항막층은 수백도가 넘는 고온 및 잉크와 접촉으로 인한 부식 및 산화 문제가 발생할 수 있는 열악한 환경에서 사용되므로, Ta, SiN과 같은 보호층을 필수적으로 필요로 한다. 그러나 최근 잉크젯 프린터의 고해상도 고속화, 대면적 인쇄성 등과 같은 다양한 요구 증가에 따라, 잉크젯 프린터의 저전력 구동이 이슈로 떠올라 열효율에 방해가 되는 보호층을 제거할 필요성이 제기되고 있다. 지금까지는 Poly-Si, $HfB_2$, TiN, TaAl, TaN _0.8 등의 물질들이 잉크젯 프린터용 전자저항막 물질로 연구되거나 실제로 사용되어져 왔으나, 이러한 물질들을 보호층을 제거하는 경우 쉽게 산화되거나, 부식되는 문제점을 가지고 있다. 따라서, 기존 전자저항막의 기능을 만족시키면서, 산화나 부식에 대한 강한 내성을 가져 보호층을 제거하더라도 안정적으로 구동이 가능한 하이브리드 기능성(히터 + 보호층)을 가지는 잉크젯 프린터용 전자저항막 물질의 개발이 시급한 실정이다. 본 연구에서는 자기조립특성을 가져 정밀제어가 가능한 원자층증착법(Atomic Layer Deposition)을 이용하여 원자/나노 단위의 미세 구조 컨트롤을 통해 내열 내산화 내부식성 저온도저항계수를 동시에 가지는 다기능성 전자저항막을 설계 및 개발하고자 하였다. 전자저항막 개발을 위하여 우수한 내부식 내산화성을 가지고 결정립 크기에 따른 온도저항계수 조절이 가능한 platinum group metal들과 전기 저항 및 내열성 향상을 위한 물질의 복합구조막을 원자증증착법으로 증착하였다. 또한, 전자저항막 증착시 미세구조와 공정 변수가 내부식성, 내산화성, 그리고 온도저항계수에 미치는 영향을 체계적으로 연구하여, proto-type의 inkjet printhead를 구현하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.291-298
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• 2012

Carbamoylphosphate (CMPO) [CMPO analogue; 2-(diphenylphosphoryl)-N-(3-(triethoxysilyl)propyl)acetamide]silane, as a functional self-assembled molecules, grafted mesoporous silicates were prepared by simple hydrolysis and condensation reaction. Pore sized tailored mesoporous silicates such as MCM-41, SBA-15, or amorphous silica nanoparticles were adopted as host materials. The surface area of ordered mesoporous silicates was ranged from 680 $m^2/g$ to 1310 $m^2/g$ with different pore diameters that estimated to be ca. 2.3~9.1 nm by BJH method. Among the OMMs host materials, SBA-15(II) has higher loading ratio (~35 wt%) of CMPO derivative than other OMMs. Accessibility to CMPO silane functional groups in the surface of mesoporous silicas was studied by lanthanide ions sorption experiments. All of the CMPO modified OMMs favors the smaller Eu(III) and Nd(III) cations than La(III) for relative larger ionic radius.

• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.163-167
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• 2021

In the present work, we studied a method for the synthesis of uniform gold-peptide hierarchical superstructures using tyrosine rich peptide, Tyr-Tyr-Leu-Tyr-Tyr (YYLYY). Peptide nanoparticles self-assembled by dityrosine bonds were synthesized through the photo-crosslinking reaction of the peptide, and gold-peptide hybrid nanoparticles were synthesized using biomineralization properties of tyrosine in a green synthetic manner. The synthesized gold-peptide hybrid nanoparticles were then characterized by transmission electron microscopy, scanning electron microscopy, dynamic light scattering, UV-vis spectroscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, the catalytic activity of gold-peptide hybrid nanoparticles was confirmed by the reduction reaction of methylene blue where the catalytic reaction rate constant was 13.4 × 10-3 s-1.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.826-831
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• 2018

This study presents fabrication of bi-compartmental particles labeled by multiple fluorescence. To compartmentalize fluorescent expression at the particle, two fluorescent dyes with less overlap of the excitation and emission spectra are selected. To ensure the fluorescence stability, the fluorescent dyes contain acrylate functional groups in the molecules so that they can be cross-linked together with monomers constituting the particle. Strong fluorescent expression and compartmentalization were observed at the particle fabricated using the selected fluorescent dyes through confocal microscopy. Furthermore, long-term fluorescence stability was verified by measuring fluorescent expression and intensity for 4 weeks. We anticipate that the bi-compartmental particles labeled by multiple fluorescence can be widely used for multi-target drug delivery system, analysis of 3 dimensional Brownian motion, and investigation of 3 dimensional complex self-assembled morphologies.

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.141-148
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• 2016

In this work, mesoporous silica (SBA-15) was synthesized via self-assembly process using triblock copolymer ($PEO_{20}PPO_{70}PEO_{20}$, P123) as template and tetraethyl orthosilicate (TEOS) as silica source under acidic condition. SBA-15 have high surface area ($704m^2g^{-1}$) and uniform pore size (8.4 nm) with well-ordered hexagonal mesostructure. Spiropyran-functionalized SBA-15 (Spiropyran-SBA-15) was synthesized via post-synthesis process using 3-(triethoxysilyl)propyl isocyanate (TESPI) and 1-(2-Hydroxyethyl)-3,3-dimethy-lindolino-6'-nitrobenzopyrylo-spiran (HDINS). Spiropyran-SBA-15 was produced with hexagonal array of mesopores without damage of mesostructre. Surface area and pore size of Spiropyran-SBA-15 were $651m^2g^{-1}$ and 8.0 nm, respectively. Optochemical properties of Spiropyran-SBA-15 was studied with chemical vapors such as EtOH, THF, $CHCl_3$, Acetone and HCl. Main peaks of photofluorescence of Spiropyran-SBA-15 exhibited blue shift in the range of 603.4~592.1 nm after exposure under EtOH, THF, $CHCl_3$, and Acetone vapors. Normalized peak intensities decreased in the range of 0.8~0.3. The main peak of photofluorescence of Spiropyran-SBA-15 showed significant blue shift of 592.1 nm after exposure under HCl vapor, while normalized peak intensity decreased to 0.1.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.255-261
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• 2016

$CaCO_3$ was applied in various industries including rubber, plastics, paint, paper, food additives, and acid neutralizer, etc., owing to its excellent physical and chemical characteristics as well as various appearances of crystals and many reserves. In particular, research on controlling the structure and shape of $CaCO_3$ has attracted considerable attention recently, because the whiteness and physical characteristics of $CaCO_3$ depend on the size and shapes of the particles. In this study, $CaCO_3$ was synthesized using $CaCl_2$ and $(NH4)_2CO_3$, which has multi-shapes and structures, using a self-assembly method with a hydrothermal method. The structure and morphology of the $CaCO_3$ could be controlled by adjusting the pH and precursor concentration. In particular, the pH adjustment appeared to be a critical factor for the morphology and crystal form. In addition, the calcite and cubic shape were obtained at pH 7, while the mixed calcite, aragonite structure, and rod shapes appeared at pH 7 and over. Through an analysis of the particle formation process, the formation of the calcium carbonate particles was confirmed. The physicochemical properties of the synthesized $CaCO_3$ were analyzed by SEM, XRD, EDS, FTIR, and TG/DTA.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.219-226
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• 2013

Organic semiconductor-based soft electronics has potential advantages for next-generation electronics and displays, which request mobile convenience, flexibility, light-weight, large area, etc. Organic field-effect transistors (OFET) are core elements for soft electronic applications, such as e-paper, e-book, smart card, RFID tag, photovoltaics, portable computer, sensor, memory, etc. An optimal multi-layered structure of organic semiconductor, insulator, and electrodes is required to achieve high-performance OFET. Since most organic semiconductors are self-assembled structures with weak van der Waals forces during film formation, their crystalline structures and orientation are significantly affected by environmental conditions, specifically, substrate properties of surface energy and roughness, changing the corresponding OFET. Organo-compatible insulators and surface treatments can induce the crystal structure and orientation of solution- or vacuum-processable organic semiconductors preferential to the charge-carrier transport in OFET.

• Polymer(Korea)
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• v.30 no.6
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• pp.512-518
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• 2006

A biodegradable polymer poly((R) -3-hydroxybutyric acid) (PHB) was conjugated with a hydrophilic polymer poly(ethylene glycol) (PEG) by the ttansesterification reaction to form the amphiphilic block copolymer. PHB with low molecular weight ($3000{\sim}30000$) was appropriated for the drug delivery materials. High molecular weight PHB was hydrolyzed by an acid-catalyst to produce the low molecular weight one. Amphiphilic block copolymer was formed the self-assembled polymeric micelle system in the aqueous solution that the hydrophillic PEG was wraped the hydrophobic PHB. Generally, polymeric micelle forms the small particle between $10{\sim}200nm$. These polymeric micelle systems have been widely used for the drug delivery systems because they were biodegradable, biocompatible, non-toxic and patient compliant. The hydroxyl group of PEG was substituted with carboxyl group which has the reactivity to the ester group of PHB. Amphiphilic block copolymer was conjugated between PHB, and modified PEG at $176^{\circ}C$ which was higher than the melting point of PHB. Transesterification reaction was verified with DSC, FTIR, $^1H-NMR$. In the aqueous solution, critical micelle concentration (CMC) of the mPEG-co-PHB copolymer measured by the fluororescence scanning spectrometer was $5{\times}10^{-5}g/L$. The shape and size of the nanoparticle was taken by dynamic light scattering and atomic force microscopy. The size of the nanoparticle was about 130 nm and the shape was spherical. Our polymeric micelle system can be used as the passive targeting drug delivery system.

• Journal of Adhesion and Interface
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• v.24 no.4
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• pp.136-142
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• 2023

In this study, TEOS was used as a silica source, and a triblock copolymer (P123) was used as a template to produce mesoporous silica with a well-ordered hexagonal mesopore array through a self-assembly method and hydrothermal process under acidic condition. (Surfactant-extracted SBA-15). Surfactant-extracted SBA-15 showed the particle shape of a short rod with a size of approximately 980 nm. The surface area and pore diameter were 730 m²g^-1 and 70.8 Å, respectively. Meanwhile, aminosilane (3-aminopropyltriethoxysilane, APTES) was grafted into the mesopores using a post-synthesis method. Mesoporous silica (APTES-SBA-15) modified with aminosilane had a well-ordered pore structure (p6mm) and well-maintained the particle shape of short rods. The surface area and pore diameter of APTES-SBA-15 decreased to 350 m²g^-1 and 60.7 Å, respectively. APTES-modified mesoporous silica was treated with a solution of rare earth metal ions (Eu³⁺, Tb³⁺) to synthesize a mesoporous silica material in which rare earth metal complexes were introduced into the mesopores. (Eu/APTES-SBA-15, Tb/APTES-SBA-15) These materials exhibited characteristic photoluminescence spectra by λ_ex=250 nm. (⁵D₄→⁷F₅ (543.5 nm), ⁵D₄→⁷F₄ (583.5 nm), ⁵D₄→⁷F₃ (620.2 nm) transitions for Tb/APTES-SBA-15; ⁵D₀→⁷F₀ (577.7 nm), ⁵D₀→⁷F₁ (592.0 nm), ⁵D₀→⁷F₂ (614.9 nm), ⁵D₀→⁷F₃ (650.3 nm) and ⁵D₀→⁷F₄ (698.5 nm) transitions for Eu/APTES-SBA-15)