• 폴리머
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• 제26권4호
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• pp.535-542
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• 2002

투석법을 이ctide-co-glycolide) (PLGA) 나노입자를 제조하고 다양한 용매에 따른 입자 크기, 약물 함유량, 생분해도 등과 같은 물리ㆍ화학적 특성을 조사하였다. Dimethylacetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO)로 제조된 PLGA 나노입자의 크기는 acetone으로 제조한 입자보다 적었다. 또한, 약물 함유량은 DMAc>DMF>DMSO=acetone 순서였다. PLGA 나노입자는 scanning electron microscopy (SEM)과 transmission electron microscopy (TEM)의 측정으로 구형임을 알 수 있었다. 계면활성제를 사용하지 않는 나노입자에 봉입된 norfloxacin (NFx)은 X-ray diffraction 분석을 통하여 입자 표면에 약물을 가지지 않는 좋은 약물 봉입 효율을 가짐을 알 수 있었다. 모델약물로 사용된 NFx의 방출속도는 약물 함유량뿐만 아니라 입사크기에 의해 좌우된다. 또한 PLGA 나노입자의 분해속도는 아세톤보다는 DMF를 사용하였을 때 더 빠르며 이는 PLGA 나노입자의 생분해성도 입자크기에 좌우된다는 것을 알 수 있었다.

• 한국자기학회지
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• 제13권2호
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• pp.59-63
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• 2003

고분자 재료인 이온교환수지 박막 안에서의 이온교환반응과 전기화학적 환원반응을 이용하여 코발트 나노 입자를 제조하였다. 코발트 나노 입자의 구조와 자기특성을 투과전자현미경과 초전도양자간섭기를 이용하여 고찰하였다. 투과전자현미경 결과로부터 고분자 박막(MF-4SK) 1 gram에 코발트가 $7.8{\times}10^{19}$ atoms 포함된 시편에서 코발트가 나노 크기로 입자를 형성하고 있음을 확인하였으며, 자기측정 결과로부터 코발트 나노 입자가 blocking temperature($T_{B}$) 이상에서 초상자성을 나타내는 것을 확인하였다. 온도에 따른 자화 측정 곡선으로부터 500 Oe 자기장 하에서 $T_{B}$가 대략 185 K인 결과를 얻었으며, 300 K에서의 자화곡선(M-H곡선) 결과를 이용하여 Langevin function fit하여 계산한 코발트 입자의 평균 반경은 4.0 nm로, 투과전자현미경으로 관찰한 크기와 일치하는 것을 확인하였다. 이 결과는 고분자 박막 내에서 코발트 나노 입자가 자성 단상(single domain) 구조를 이루고 있음을 보여주는 것으로, 강자성 나노 입자들의 초상자성 거동을 고찰하였다.

• 한국표면공학회지
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• 제56권4호
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• pp.233-242
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• 2023

In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

• 폴리머
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• 제33권5호
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• pp.429-434
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• 2009

본 연구에서는 PMMA의 전기 방사 조건을 자세히 조사하였다. 즉, DMF 및 THF를 용매로 하여 최적의 혼합비 및 농도를 조사하였다. 또한, 은을 첨가했을 때 용액의 전도성 및 섬유 직경에 대해 검토하였고, 얻어진 나노섬유 부직포의 항균성을 조사하였다. 그 결과 DMF와 THF가 7:3이며 18 wt%일 때 섬유형성능이 우수하였고, 은을 1000ppm 넣어 전기방사하였을 때 섬유 직경은 100-400 nm 이었다. 투과형 전자현미경으로 관찰한 결과 은 나노입자는 섬유의 테두리에 분포되어 있었으며, 이들은 그램 양성균 및 그램 음성균에 대해 높은 항균성을 나타내었다.

• 한국분말재료학회지
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• 제12권3호
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• pp.225-230
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• 2005

In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below $130^{\circ}C$ in air was $10\~40$ times higher than that of the air- passivated particles.

• Bulletin of the Korean Chemical Society
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• 제23권4호
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• pp.563-566
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• 2002

Copper complexes have been directly incorporated into cellulose acetate (CA) and the resulting light blue colored homogeneous films of 5-20 wt.% copper acetate complex concentrations are found to be thermally stable up to 200 $^{\circ}C$. The reaction chem istry of Cu in CA has been investigated by reacting them with small gas molecules such as CO, H2, D2, O2, NO, and olefins in the temperature range of 25-160 $^{\circ}C$, and various Cu-hydride, -carbonyl, -nitrosyl, and olefin species coordinated to Cu sites in CA are characterized by IR and UV/Vis spectroscopic study. The reduction of Cu(II) complexes by reacting with H2 gas at the described conditions results in the formation of Cu2O and copper metal nanoparticles in CA, and their sizes in 30-120 nm range are found to be controlled by adjusting metal complex concentration in CA and/or the reduction reaction conditions. These small copper metal particles show various catalytic reactivity in hydrogenation of olefins and CH3CN; CO oxidation; and NO reduction reactions under relatively mild conditions.

• Macromolecular Research
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• 제17권2호
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• pp.137-139
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• 2009

• 한국해양공학회지
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• 제27권5호
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• pp.99-104
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• 2013

Recently, various nanoparticles have been used for filler in polymer matrices. The particles of nano size are whether high or not cross-link density in polymer affects the thermal and mechanical properties of one. The properties change as a result of chemical reactions between the nanoparticles and the surface of the polymer. There are two models for nanocomposites: "repulsive interaction" and "attractive interaction" between the nanoparticles and matrix. In this study, the variation in the curing mechanism was examined when nano-size $TiO_2$ was dispersed into an epoxy (Bisphenol A, YD-128) with different curing agents. The results of this study showed that the exothermic temperature and Tg in the case of the nanoparticles used (Jeffamine) (D-180) at room temperature were reduced by an increase in the $TiO_2$ contents because of the "repulsive interaction" between the nanoparticles and the matrix. The tensile strengths were increased by increasing amounts of $TiO_2$ until 3 wt% because of a dispersion strengthening effect caused by the nanoparticles, because of the repulsive interaction. However, such tensile properties decreased at 5 wt% of $TiO_2$, because the $TiO_2$ was agglomerated in the epoxy. In contrast, in the case of the nanoparticles that used NMA and BDMA, the exothermic temperature and Tg tended to rise with increasing amounts of $TiO_2$ as a result of the "attractive interaction." This was because the same amounts of $TiO_2$ were well dispersed in the epoxy. The tensile strength decreased with an increase in the $TiO_2$ contents. In the general attractive interaction model, however, the cross-link density was higher, and tensile strength tended to increase. Therefore, for the nanoparticles that used NMA, it was difficult to conclude that the result was caused by the "attractive model."

• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.799-804
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• 2008

An amphiphilic diacetylene compound was deposited on the surface of nano sized magnetite particles ($Fe_3O_4$) using a self-assembly method. The diacetylene molecular assembly formed on the surface of nanoparticle was subjected to photopolymerization. This resulted in the formation of a polymeric assembly on the surface of the nanoparticles in which the adjacent diacetylene molecules were connected through conjugated covalent networks. The presence of immobilized polymer species on the surface of nanoparticles is expected to protect them from agglomeration and ripening, thereby stabilizing their physical properties. In this work, $Fe_3O_4$ nanoparticles were prepared by chemical coprecipitation method and the diacetylene molecule 10,12- pentacosadiynoic acid (PCDA) was anchored to the surface of $Fe_3O_4$ nanoparticles through its carboxylate head group. Irradiation of UV light on the nanoparticles containing immobilized diacetylenes resulted in the formation of a polymeric assembly. Presence of diacetylene molecules on the surface of nanoparticles was confirmed by X-ray photoelectron spectroscopy and FT-IR measurements. Photopolymerization of the diacetylene assembly was detected by UV-Visible spectroscopy. Magnetic properties of the nanoparticles coated with polymeric assembly were investigated with SQUID and magnetic hysteresis showed superparamagnetic behaviors. The results put forward a simple and effective method for achieving polymer coating on the surface of magnetic nanoparticle.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.182-182
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• 2006

PLLA grafted Hydroxyapatite / polylactide (g-HA/PLA) composites were prepared by three grafting methods. The modified particles (p-HA) were dispersed more uniformly in the PLLA matrix than pure n-HA. The p-HA/PLLA composites exhibited better mechanical properties and thermal stability than the n-HA/PLLA composites. The composites also demonstrated improved cell compatibility due to the good biocompatibility of the HAP nanoparticles and the more uniform distribution of the PLLA-grafted HAP nanoparticles on the film surface. All of these results indicated that the p-HAP/PLLA nano-composites might have a promising medical application in bone repair and in bone tissue-engineering.