• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.345-351
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• 2004

Highly ordered pure-silica MCM-41 materials possessing well-defined morphology have been successfully prepared with surfactant used as a template. The fabrication of mesoporous silica has received considerable attention due to the need to develop more efficient materials' for catalysis, separations, and chemical sensing. The surface modified MCM-41 was used as anadsorbent for biomolecules. Silica-supported organic groups and DNA adsorption on surface modified MCM-41 were investigated by FT-IR and UV-Vis spectrometer, respectively. The use of MCM-41 as the modification of electrode surfaces were investigated electrochemical properties of metal mediators with biomolecules. The modified ITO electrodes increased peak currents for a redox process of $[Ru(bpy)_3]^{2+}$ relative to the bare electrode. The electrochemical detection of DNA by cyclic voltammetry when the current is saturated in the presence of the mediator appeared more sensitive due to a higher catalytic current on the MCM-41 supported electrodes modified by carboxylic acid functional groups. The carboxyl or amine groups on the surface of MCM-41 interact and react with the $-NH_2$ groups of guanine and backbone, respectively. Highly ordered mesoporous materials with organic groups could find applications as DNA sensors.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.267-272
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• 2012

Considering the properties of the carbon nano tubes (CNT), their inclusion into the polymer matrix vastly increases the properties of the resultant composite. However, this is not the case due to the poor interfacial adhesion of the CNT and the polymer matrix. The present approach focuses on increasing the interaction between the polymer matrix and the CNT through the chemical modification of the CNT resulting in allyl ester functionalized carbon nanotubes (ACNT) and silane functionalized carbon nano tubes (SCNT) which are capable of reacting with the polymer matrix during the curing reaction. The addition of ACNT/SCNT into unsaturated polyester resin (UPR) resulted in the improvement of the electrical properties of resulted nanocomposites in comparison to the CNT. The surface resistivity, volume resistivity, dielectric strength, dry arc resistivity, and the comparative tracking index of the nanocomposites were significantly improved in comparison to CNT. The chemical modification of CNT was confirmed via spectroscopy.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.5
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• pp.399-409
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• 2018

Prussian blue is known as a superior material for selective adsorption of radioactive cesium ions; however, the separation of Prussian blue from aqueous suspension, due to particle size of around several tens of nanometers, is a hurdle that must be overcome. Therefore, this study aims to develop granule type adsorbent material containing Prussian blue in order to selectively adsorb and remove radioactive cesium in water. The surface of granular activated carbon was grafted using a covalent organic polymer (COP-19) in order to enhance Prussian blue immobilization. To maximize the degree of immobilization and minimize subsequent detachment of Prussian blue, several immobilization pathways were evaluated. As a result, the highest cesium adsorption performance was achieved when Prussian blue was synthesized in-situ without solid-liquid separation step during synthesis. The sample obtained under optimal conditions was further analyzed by scanning electron microscope-energy dispersive spectrometry, and it was confirmed that Prussian blue, which is about 9.7% of the total weight, was fixed on the surface of the activated carbon; this level of fixing represented a two-fold improvement compared to before COP-19 modification. In addition, an elution test was carried out to evaluate the stability of Prussian blue. Leaching of Prussian blue and cesium decreased by 1/2 and 1/3, respectively, compared to those levels before modification, showing increased stability due to COP-19 grafting. The Prussian blue based adsorbent material developed in this study is expected to be useful as a decontamination material to mitigate the release of radioactive materials.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.647-659
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• 2008

Colloids are a heterogeneous system in which particles of a few nanometers to hundreds micrometers in size are finely dispersed in liquid medium, but show homogeneous properties in macroscopic scale. They have attracted much attention not only as model systems of natural atomic and molecular self-assembled structures but also as novel structural materials of practical applications in a wide range of areas. In particular, recent advances in colloidal science have focused on nano-bio materials and devices which are essential for drug discovery and delivery, diagnostics and biomedical applications. In this review, first we introduce nano-bio colloidal systems and surface modification of colloidal particles which creates various functional groups. Then, various methods of fabrication of colloidal particles using holographic lithography, microfluidics and virus templates are discussed in detail. Finally, various applications of colloids in metal inks, three-dimensional photonic crystals and two-dimensional nanopatterns are also reviewed as representative potential applications.

• Journal of Sensor Science and Technology
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• v.33 no.2
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• pp.105-111
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• 2024

In this study, the H₂S gas sensing characteristics were evaluated using surface-modified SnO₂ microparticles by tip sonication. The surface-modified SnO₂ microparticles were synthesized using the following sequential process. First, bare SnO₂ microparticles were synthesized via a hydrothermal method. Then, the surfaces of bare SnO₂ microparticles were modified with Ti nanoparticles during tip sonication. The sensing characteristics of SnO₂ microparticles modified with Ti were systematically investigated in the range of 100-300℃, compared with the bare SnO₂ microparticles. In this study, we discuss in detail the improved H₂S sensing characteristics of SnO₂ microparticles via Ti nanoparticle modification.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.225-230
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• 2016

Since the development of anodic aluminum oxide (AAO), extensive studies have been conducted ranging from fundamental research to the applications of AAO. Most of the research on AAO structures have focused on well-aligned nanoporous structures fabricated under specific conditions. This study investigated fabricable AAO structures with anodization performed with various temperatures, electrical potentials, and basal plane surfaces. As a result, nanoporous and nanofibrous structures were fabricated. The nanopores were formed at a relatively lower temperature and potential, and the nanofibers were formed at a relatively higher temperature and potential regardless of the basal plane surface. The shape of the base surface was found to influence the structural arrangement in nanoporous morphologies. These interesting findings relating to new morphologies have the potential to broaden the possible applications of AAO materials.

• Textile Coloration and Finishing
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• v.21 no.5
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• pp.16-20
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• 2009

Films of Poly(ethylene oxide), PEO, were modified to impart hydrophilicity via UV irradiation. The UV irradiation treatment produced new photo-oxidized groups of carbonyl and ether groups as indicated in ATR and ESCA analysis. It was found that water contact angle decreased from $15^{\circ}C$ to $10^{\circ}C$ and total surface energy of PEO increased from 54.2 mN/m to 76.6 mN/m with increasing UV energy, which was attributed to significant contribution of acid base interaction of the photo-oxidized PEO rather than nonpolar interaction originating from the dominant increase in Lewis acid parameter. The increased hydrophilicity and surface energy were also proved by the decreased water wetting time.

• Carbon letters
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• v.11 no.2
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• pp.112-116
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• 2010

The objective of this study was to evaluate the possibility of simultaneous removal of ammonium, nitrate and phosphorus in water using the zeocarbon. In this study, the surface of zeocarbon was modified by acid because of difficulty in application of water treatment. After surface modification, the strength was enhanced about 62% higher than that of original one. The removal efficiency of ammonium and nitrate using the modified zeocarbon was about 47% and 32%, respectively and were higher than that of zeocarbon. In batch type experiment on the simultaneous removal of ammonium, nitrate and phosphorus, the presence of phosphorus did not have influence on nitrogen removal efficiency. Concomitantly, removal efficiency of phosphorus was obtained was about 35%. This indicates that the surface modified zeocarbon can be applied for simultaneous removal of nitrogen and phosphorus. Consequently, our results could be used as basic data to design of one-stage nitrogen/phosphorus simultaneous removal system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.3
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• pp.122-126
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• 2006

In this study, composite materials were put to dry interfacial treatment by use of plasma technology It has been presented that the optimum parameters for the best wettability of the samples at the time of generation of plasma were oxygen atmosphere, 0.1 Torr of system pressure, 100 W of discharge power, and 3 minutes of discharge time. The decrease in surface potential of charged samples by corona discharge indicates that the amount of accumulated electrical charges reduces and the charges that have been injected lessen rapidly when the duration of UV irradiation increases. The surface resistivity and the tensile strength of plasma treated samples, a longer UV irradiation time resulted in decreased insulation.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.161-161
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• 1999

In the field of material science, the interests and efforts to modify the surface of materials in agreement with the need of usage have been extensively increasing. he modification to improve the wettability of surface is very important is terms of adhesion, printing, etc. It is very difficult to modify metal surface into hydrophilic one. therefore, surfactant coating has been generally used in many cases. However, surfactant has disadvantages such as environmental problem, soluble in water. in this study, hydrophilic polymer films as alternative of surfactant were deposited on metal substrate by DC plasma polymerization. Hydrophilic polymer films deposited by DC plasma show many merits such as good wettability, stone adhesion to substrate, high resistance to most chemicals. Monomer gas and reactive gas were used as source plasma polymerization. Plasma polymerized films were fabricated with process parameters of deposition time, ratio of gas mixture, current, pressure, etc. Effects of these variables on wettability of plasma polymer films will be discussed. With XPS and FT-IR analyses of plasma polymeric films, the relation between wettability and chemical state of polymer films by DC plasma was investigated.