• 센서학회지
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• 제31권4호
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• pp.214-217
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• 2022

The effect of inductively coupled plasma (ICP) treatment with O₂ gas on the surface properties of poly(ether sulfone) (PES) was investigated. X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical characteristics of the O₂ plasma-treated PES films. The surface roughness of the pristine and O₂ plasma-treated PES films for different RF powers of the ICP was determined using an atomic force microscope (AFM). The contact angles of the PES films were also measured, using which the surface free energies were calculated. The O1s XPS spectra of the PES films revealed that the number of polar functional groups increased following the O₂ plasma treatment. The AFM analysis showed the average surface roughness increased from 1.01 to 4.48 nm as the RF power of the ICP was increased. The contact angle measurements revealed that the PES films became more hydrophilic as the RF power of the ICP was increased. The total surface energy increased with the RF power of the ICP, resulting from the increased polar energy component.

• 한국표면공학회지
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• 제29권6호
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• pp.851-856
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• 1996

Copper Phthalocyanine (CuPc) thin films were fabricated on the silicon wafers by plasma activated evaporation method and structural analysis were carried out with various spectroscopies. The CuPc films had dense and smooth morphology and they also showed good mechanical properties and chemical resistance. The main molecular structure of the CuPc, which is the conjugated aromatic heterocyclic ring structure, was maintained even in the plasma process. However, metal-ligand (Cu-N) bands were deformed by the plasma process and the structure became amorphous especially at higher process pressures. Oxygen impurities were incorporated in the film and carboxyl functional groups were formed at the peripheral benzene ring. The structure and morphology of the films were dependent on the process pressure but relatively irrespective of the RF power.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.182-182
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• 2011

We investigated the adsorption structures of serine on a Ge(100) surface by core-level photoemission spectroscopy (CLPES) in conjunction with density functional theory (DFT) calculations. The adsorption energies calculated using DFT methods suggested that four of six adsorption structures were plausible. These structures were the "O-H dissociated-N dative bonded structure", the "O-H dissociation bonded structure", the "Om-H dissociated-N dative bonded structure", and the "Om-H dissociation bonded structure" (where Om indicates the hydroxymethyl oxygen). These structures are equally likely, according to the adsorption energies alone. The core-level C 1s, N 1s, and O 1s CLPES spectra confirmed that the carboxyl oxygen competed more strongly with the hydroxymethyl oxygen during the adsorption reaction, thereby favoring formation of the "O-H dissociated-N dative bonded" and "O-H dissociation bonded" structures at 0.30 ML and 0.60 ML, respectively. The experimental results were corroborated theoretically by calculating the reaction pathways leading to the two adsorption geometries. The reaction pathways indicated that the "O-H dissociated-N dative bonded structure" is the major product of serine adsorption on Ge(100) due to comparably stable adsorption energy.

• Carbon letters
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• 제11권3호
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• pp.224-234
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• 2010

Four activated carbons were produced by two-stage process as followings; semi-carbonization of indigenous biomass waste, i.e. cotton stalks, followed by chemical activation with KOH under various activation temperatures and chemical ratios of KOH to semi-carbonized cotton stalks (CCS). The surface area, total pore volume and average pore diameter were evaluated by $N_2$-adsorption at 77 K. The surface morphology and oxygen functional groups were determined by SEM and FTIR, respectively. Batch equilibrium and kinetic studies were carried out by using a basic dye, methylene blue as a probe molecule to evaluate the adsorption capacity and mechanism over the produced carbons. The obtained activated carbon (CCS-1K800) exhibited highly microporous structure with high surface area of 950 $m^2/g$, total pore volume of 0.423 $cm^3/g$ and average pore diameter of 17.8 ${\AA}$. The isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 222 mg/g for CCS-1K800. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The pseudo-second-order model fitted better for kinetic removal of MB dye. The results indicate that such laboratory carbons could be employed as low cost alternative to commercial carbons in wastewater treatment.

• Carbon letters
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• 제9권1호
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• pp.8-16
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• 2008

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acid of varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and of the oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(II) and Cd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by the column method. Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of the carbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developing new surface oxygen functional groups of acidic nature. $HNO_3$-oxidized carbons exhibited high adsorption capacities for Pb(II) and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase of the solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surface acidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigated carbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.

• 마이크로전자및패키징학회지
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• 제14권4호
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• pp.49-56
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• 2007

습식 개질전처리를 통해 무전해 도금 니켈/폴리이미드 박막을 형성하였으며, 이때 도금 후처리 공정인 후속 열처리 조건에 따른 무전해 니켈 도금 박막과 폴리이미드 사이의 필 강도를 $180^{\circ}C$인 경우 필 강도는 $38.6{\pm}1.1g/mm$에서 $180^{\circ}C$ 처리 시에 $26.8{\pm}2.2g/mm$로 감소하였다. 습식 개질전처리에 의해 폴리이미드 표면에 형성된 carboxyl 결합과 amide결합은 니켈과 폴리이미드 사이의 계면 접착기구와 밀접한 연관성이 있는 것으로 판단된다. 후속 열처리 온도에 상관없이 파괴경로는 모두 폴리이미드 내부였으며, 이때 후속 열처리 온도에 따른 무전해 니켈 도금 박막과 폴리이미드 사이의 박리 강도 거동은 파면 부근에 형성된 carbonyl oxygen결합의 감소와 밀접한 연관성이 있는 것으로 판단된다.

• Carbon letters
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• 제10권2호
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• pp.114-122
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• 2009

Crushed, depitted peach stones were impregnated activated with 50% $H_3PO_4$ followed by pyrolysis at $500^{\circ}C$. Two activated carbons were produced, one under its own evolved gases during pyrolysis, and the second conducted with air flow throughout the carbonization stage. Physicochemical properties were investigated by several procedures; carbon yield, ash content, elemental chemical analysis, TG/DTG and FTIR spectra. Porosity characteristics were determined by the conventional $N_2$ adsorption at 77 K, and data analyzed to get the major texture parameters of surface area and pore volume. Highly developed activated carbons were obtained, essentially microporous, with slight effect of air on the porous structure. Oxygen was observed to be markedly incorporated in the carbon matrix during the air treatment process. Cation exchange capacity towards Cu (II) and Cd (II) was tested in batch single ion experimental mode, which proved to be slow and a function of carbon dose, time and initial ion concentration. Copper was up taken more favorably than cadmium, under same conditions, and adsorption of both cations was remarkably enhanced as a consequence of the air treatment procedure. Sequestration of the metal ions was explained on basis of the combined effect of the oxygen functional groups and the phosphorous-containing compounds; both contributing to the total surface acidity character.

• 한국표면공학회지
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• 제29권5호
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• pp.345-349
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• 1996

The wetting property of polymer surfaces is very important for practical applications. Plasma source ion implantation technique was used to improve the wetting properties of polymer surfaces. Poly(ethylene terephtalate) and other polymer sheets were mounted on the target stage and an RF plasma was generated by means of an antenna located inside the vacuum chamber. High voltage pulses of up to -10kV, 10 $\mu$sec, and up to 1 kHz were applied to the stage. The samples were implanted for 5 minutes with using Ar, $N_2,O_2,CH_4,CF_4$ and their mixture as source gases. A contact angle meter was used to measure the water contact angles of the implanted samples and of the samples stored in ambient conditions after implantation. The modified surfaces were analysed with Time-Of-Flight Mass Spectrometer (TOF-SIMS) and Auger Electron Spectroscopy (AES). The oxygen-implanted samples showed extremely low water contact angles of $3^{\circ}C$ compared to $79^{\circ}C$ of unimplanted ones. Furthermore, the modified surfaces were relatively stable with respect to aging in ambient conditions, which is one of the major concerns of the other surface treatment techniques. From TOF-SIMS analysis it was found that oxygen-containing functional groups had been formed on the implanted surfaces. On the other hand, the $CF_4$-implanted samples turned out to be more hydro-phobic than unimplanted ones, giving water contact angles exceeding $100^{\circ}C$ . The experiment showed that plasma source ion implantation is a very promising technique for polymer surface modification especially for large area treatment.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3269-3273
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• 2013

Graphene oxide (GO) has been of particular interest because it provides unique properties due to its high surface area, chemical functionality and ease of mass production. GO is produced by chemical exfoliation of graphite and is decorated with oxygen-containing groups such as phenol hydroxyl, epoxide groups and ionizable carboxylic acid groups. Due to the presence of those functional groups, GO can be utilized as a novel platform for hybrid nanocomposites in chemical synthetic approaches. In this work, GO-$SnO_2$ nanocomposites have been prepared through the spontaneous formation of molecular hybrids. When $SnO_2$ precursor solution and GO suspension were simply mixed, $Sn^{2+}$ was spontaneously formed into $SnO_2$ nanoparticles upon the deoxygenation of GO. Through further chemical reduction by adding hydrazine, reduced GO-$SnO_2$ hybrid was finally created. Our investigation for the electrocapacitive properties of hybrid electrode showed the enhanced performance (389 F/g), compared with rGO-only electrode (241 F/g). Our approach offers a scalable, robust synthetic route to prepare graphene-based nanocomposites for supercapacitor electrode via spontaneous hybridization.

• 공업화학
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• 제30권2호
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• pp.212-218
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• 2019

탄소나노튜브의 함산소불소화가 무전해 니켈도금 및 전자파 차폐효율에 미치는 영향을 확인하기 위하여, 탄소나노튜브를 산소 및 불소 혼합가스로 표면처리 후, 무전해 니켈도금을 실시하였다. 제조된 탄소나노튜브의 전자파 차폐 특성을 평가하기 위하여 폴리이미드 필름 위에 얇은 필름을 제작하였다. X-선 광전자분광법(XPS)을 이용하여 함산소불화 탄소나노튜브의 표면화학적 특성을 확인하였다. 또한, 열중량분석법(TGA)과 주사전자현미경(SEM) 분석결과, 함산소불소화 정도에 따른 탄소나노튜브의 니켈도금된 양과 표면 형상이 변화하였음을 알 수 있었다. $O_2:F_2=1:9$로 처리 후, 니켈도금된 탄소나노튜브는 1 GHz에서 약 19.4 dB 이상으로 가장 우수한 전자파 차폐효율을 나타내었다. 이러한 결과는 탄소나노튜브의 함산소불소화로 표면에 형성된 산소 및 불소 관능기 때문으로 여겨지며, 이 관능기들은 적절한 양의 니켈도금을 가능하게 하며 도금 용액에서의 분산성을 향상시켰다.