• Textile Coloration and Finishing
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• v.26 no.3
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• pp.159-164
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• 2014

Biodegradable Poly(butylene succinate), PBS, was photooxidized by UV/ozone irradiation and the effect of UV energy on the surface properties of the UV-irradiated PBS film were investigated by the measurement of reflectance, surface roughness, contact angles, chemical composition, and zeta potential. With increasing UV energy, reflectance decreased in the visible and ultraviolet regions particularly at the wavelength of 380nm. The irradiation produced nano-scale surface roughness including the maximum peak-to-valley roughness increased from 106nm for the unirradiated sample to 221nm at the UV energy of $10.6J/cm^2$. The improved hydrophilicity was due to the higher $O_{1s}/C_{1s}$ resulting from the introduction of polar groups such as C-O and C=O bonds. The surface energy of the PBS increased from $42.1mJ/m^2$ for the unirradiated PBS to $56.8mJ/m^2$ at the irradiation of $21.2J/cm^2$. The zeta potentials of the UV-irradiated PBS also decreased proportionally with increasing UV energy. The cationic dyeability of the PBS increased accordingly resulting from the improved affinity of the irradiated PBS surfaces containing photochemically introduced anionic and dipolar dyeing sites.

• Journal of Pharmaceutical Investigation
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• v.37 no.1
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• pp.39-43
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• 2007

Previously, we have reported that PLGA nanoparticles were prepared for sustained release of water-soluble blue dextran and the particle size, in vitro release pattern and encapsulation were modulated by varying polymers. This study was designed to encapsulate plasmid DNA in PLGA nanoparticles and to investigate the effect of Polymers and temperatures. PLGA nanoparticles were fabricated with poloxamer 188 (P188) or poloxamer 407 (P407) by using spontaneous emulsification solvent diffusion method. As a model plasmid DNA, pCMV-Taq2B/1L-18 was encapsulated in PLGA nanoparticles. Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing plasmid DNA were investigated. Particle sizes of PLGA nanoparticles prepared with P188 and P407 were in the range of 200-330 nm and 250-290 nm, respectively. Zeta potentials of nanoparticles were negative regardless of nanoparticle compositions. Encapsulation efficiency of P407 nanoparticles prepared at $30^{\circ}C$ was higher than those at other preparation condition. From the results, the PLGA nanoparticles prepared with poloxamers at different temperature, could modulate the particles size of nanoparticles, and encapsulation efficiency of plasmid DNA.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.93-98
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• 2010

In this work, the electrochemical properties of surface treated multi-walled carbon nanotubes (MWNTs) were studied. Nitrogen and oxygen functional groups of the MWNTs were introduced by urea and acidic treatment, respectively. The surface functional groups of the MWNTs were confirmed by X-ray photoelectron spectroscopy (XPS) measurements and zeta-potential method. The characteristics of $N_2$ adsorption isotherm at 77 K, specific surface area, and total pore volumes were investigated by BET eqaution, BJH method and t-plot method. Electrochemical properties of the functionalized MWNTs were accumulated by cyclic voltammetry at the scan rates of 50 $mVs^{-1}$ and 100 $mVs^{-1}$ in 1M $H_2SO_4$ as electrolytes. As a result, the functionalized MWNTs led to an increase of capacitance as compared with pristine MWNTs. It was found that the increase of capacitance for urea treated MWNTs was attributed to the increase in density of surface functional groups, resulting in improving the wettability between electrode materials and charge species.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.386-390
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• 2016

The surface of carbon nanotubes (CNTs) was modified by fluorination and applied to conductive materials to improve the energy efficiency of a capacitive desalination (CDI) electrode. CNTs were fluorinated at room temperature with a mixed gas of fluorine and nitrogen, and activated carbon based CDI electrodes were then prepared by adding 0-0.5 wt% of untreated CNTs or fluorinated CNTs with respect to the activated carbon. Fluorinated CNTs showed improved dispersibility in the electrode and also slurry as compared to untreated CNTs, which was confirmed by the zeta potential and scanning electron microscopy. Fluorinated CNTs added electrodes showed higher desalination efficiency but lower energy consumption than those of using untreated CNTs added electrodes. This was attributed to the decrease in the resistance of CDI electrodes due to the improved dispersibility of CNTs by fluorination.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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• pp.46-55
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• 2014

In this study, we modified the surface of nanofibrillated cellulose (NFC) through LbL (Layer-by-Layer) multilayering process with polyelectrolytes and investigated the effects of the NFC modification on the charge of NFC surface and the dewatering ability of NFC suspension. The multilayering process was done onto NFC fibers using polydiallyldimethylammonium chloride (PDADMAC) and poly-sodium 4-styrene sulfonate (PSS) under different dosage and washing conditions. When the washing was carried out in every adsorption stage, the modified NFC had strong cationic or anionic charge depending on the type of polyelectrolyte in the outermost layer and the dewatering ability was not affected. In the case of no washing treatment or washing in the final adsorption stage, however, the zeta potential of NFC was close to an isoelectric point so that the dewatering ability increased remarkably. Low addition level of polyelectrolytes also showed the similar results. The mixing of NFC suspensions with opposite charge resulted in higher network strength and improved dewatering ability due to the flocculation.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.71-71
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• 2011

전류를 흘렸을 때 양극과 음극에 따라 움직이는 미세한 나노입자를 이용하여 색, 글자, 그림 등을 표시하는 응용디스플레이 기술이 전기영동디스플레이(electrophoretic display)이다. 최근 전자종이 등 상품화가 진행되면서 전기영동디스플레이에 대한 관심증대와 함께 기술개발이 지속적으로 진행되고 있다. 본 연구에서는 분산중합을 이용하여 $TiO_2$ core 입자에 polystyrene을 shell로 코팅하여 마이크로캡슐형의 전기영동디스플레이에 적합한 입자를 제조하고 성능을 분석하였다. 먼저 분산제의 종류, 모노머의 농도, 개시제의 농도에 따라 제조된 대전복합입자의 크기 및 분포를 보면, 분산제의 종류를 달리 하였을때를 제외하고 대체로 균일하였다. 입경의 변화를 보면, 약 200-300nm의 $TiO_2$가 개질에 의해 400-500nm의 입경을 나타내는 것으로부터 200nm 두께의 shell층을 갖는다는 것을 확인 할 수 있었다. 또한 분산제의 종류에 따라서는 분산제를 사용하지 않는 경우가 오히려 제조된 입자의 분포가 균일함을 알 수 있었고 모노머의 농도에 따른 변화는 볼 수 없었으며 입경분포가 균일한 입자가 제조되었음을 알 수 있었다. 대전복합입자의 TGA 곡선으로부터 $300^{\circ}C$ 부근에서 polystrene shell에 의한 분해를 볼 수 있었고 $600^{\circ}C$ 이후에 잔류된 core의 $TiO_2$ 입자를 확인 할 수 있었다. 이 결과로부터 $TiO_2$ core-polystyrene shell형의 전자 종이용 대전복합입자의 제조를 확인 할 수 있었다. 또한 제조된 대전복합입자의 zeta potential을 보면, (+)전하를 띄며 64.8mV의 비교적 높은 zeta potential을 가지는 것을 확인 할 수 있었다. 그리고 $TiO_2$ 대전복합입자와 같은 방법으로 제조된 흑색 대전복합입자를 혼합하여 cell test를 측정한 결과, cell에 ${\pm}$10V의 저전압을 가했을 때에도 비교적 응답속도가 빠른 입자의 구동현상을 확인 할 수 있었다.

• Journal of Pharmaceutical Investigation
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• v.33 no.4
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• pp.319-322
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• 2003

Many studies have been attempted to overcome the problems of paclitaxel related to the extremely low aqueous solubility of paclitaxel and the unexpected side-effects caused by $Cremophor^{\circledR}$ EL in a commercial paclitaxel formulation, $Taxol^{\circledR}$. In order to formulate a new delivery system suitable for intravenous administration without toxic excipients, in this study, paclitaxel was incorporated into solid lipid nanoparticles (Px-SLN) by hot homogenization technique using a microfluidizer. Particle size and zeta potential were measured by a Zetasizer. In vitro drug release experiment was performed by a dialysis diffusion method. Each Px-SLN or $Taxol^{\circledR}$ was intravenously administered to the male Sprague-Dawley rats at a dose of 5 mg/kg as paclitaxel. Blood samples were deproteinated with acetonitrile and assayed for paclitaxel by the validated HPLC/MS/MS method. Mean particle size and zeta potential were measured as 72.1 nm (< Polydispersity 0.3) and -41.5 mV, respectively. The content of paclitaxel in SLN was 1.42 mg/ml and the drug loading efficiency was $71.2{\pm}4.3%$. The $AUC_t$ of Px-SLN was 3.4-fold greater than that of $Taxol^{\circledR}$. The Px-SLN might be a promising candidate for an alternative formulation for the parenteral delivery of paclitaxel.

• Journal of Pharmaceutical Investigation
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• v.39 no.1
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• pp.59-63
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• 2009

Soybean phosphatidylcholine microparticles loaded with cyclosporin A (CsA) were prepared by the modified emulsion solvent diffusion and ionic gelation method, in which chitosan on the surface of the microparticles was crosslinked with various concentrations of tripolyphosphate (TPP). The morphology of the particles was characterized by scanning electron microscopy (SEM). The change of particle size and zeta-potential by chitosan on the surface of the lipid microparticles were systematically observed. The encapsulation efficiency and loading capacity of CsA in the particles were determined by high performance liquid chromatography (HPLC). In vitro release kinetics was studied using the dialysis method. In the results, the mean particle size and the zeta-potential of lipid microparticles increased when the attached chitosan was cross-linked (from 2.5 to 6.2 ${\mu}m$ and from -37.0 to +93.0 mV, respectively). The cyclosporin A-loaded lipid microparticles appeared discrete and spherical particles with smooth surfaces. The encapsulation efficiency of CsA was between 79% and 90% while the loading capacity was between 41% and 56%. In vitro release study showed that the crosslinkage of chitosan by TPP significantly delayed the release of CsA from the particles in a concentration-dependent manner. Thus, the release of CsA from the lipid microparticles could be controlled by tripolyphosphate used as a cross-linking agent.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1327-1331
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• 2005

This study was to investigate the reduction of hydration heat by utilizing industrial by-products such as BFS(Blast Furnace Slag). DM(Dredged Mud) was used by parent soil and Ordinary portland cement was used by cementing material. Additive added to reduce the heat of hydration was BFS. From the results of experiment, hydration heat was decreased in accordance with the addition of BFS. The reason was that surface of BFS coated with aluminosulfate. Initial uniaxial strength was low, neither was not long term uniaxial strength. It was concluded that silica rich layer($H_2SiO_4^{4-}$) in solid phase early in the reaction of hydration was difficultly moved in liquid phase due to the increase of ZP(Zeta Potential). However, the ZP in the later hydration was decreased due to the acceleration of mobility of silica rich layer($H_2SiO_4^{4-}$). Therefore, long term physical properties such as uniaxial strength revealed.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.673-679
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• 2008

In this study, Mesoporous silica were prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide(CTMABr) as a template. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of Mesoporous silica were determined by XRD, SEM, and BET. N$_2$ adsorption isotherm characteristics, including the specific surface area(S$_{BET}$), total pore volume(V$_T$), and average pore diameter(D$_{BJH}$), were determined by BET. Also, the adsorption character of Pb(II) and Cd(II) ion on Mesoporous silica were measured using ICP. As a result, a SBET of 100$\sim$1,500 m$^2$/g was determined from the N$_2$ adsorption isotherm. Also, the average pore diameter of 2$\sim$4 nm. The adsorption of Pb ion and Cd ion on Mesoporous silica become different depending on the pH of solution. The adsorption amount of Mesoporus silica had higher than that of silicagel.