• 대한화학회지
• /
• 제54권1호
• /
• pp.93-98
• /
• 2010

본 연구에서는 Urea와 산 처리로 질소 및 산소 관능기가 도입된 다중벽 탄소나노튜브를 각각 제조하였으며, 표면처리에 따른 전기이중층 커패시터 (EDLCs) 특성을 관찰하였다. XPS, zeta-potential, 및 BET 분석방법을 이용하여 구조특성을 확인하였으며, 전기화학적 특성은 1 M 황산용액의 전해질에서 각각 50 $mVs^{-1}$과 100 $mVs^{-1}$의 주사속도로 순환전류 전압곡선 특성 실험을 통해 고찰하였다. 실험 결과로부터 MWNTs의 질소 원소구성비가 늘어날수록 축전용량이 증가하는 것을 확인하였으며, Urea 처리된 MWNTs의 축전용량이 가장 높은 수치를 나타내었다. 이는 전극 표면과 전하 활성종 간의 젖음성이 증가하고, 표면 관능기의 밀도가 증가하기 때문인 것으로 사료된다.

• Carbon letters
• /
• 제12권4호
• /
• pp.236-242
• /
• 2011

The oxyfluorination effects of activated carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Electrospun CFs were prepared from a polyacrylonitrile/N,N-dimethylformamide solution via electrospinning and heat treatment. The electrospun CFs were chemically activated in order to generate the pore structure, and then oxyfluorination was used to modify the surface. The samples were labeled CF (electrospun CF), ACF (activated CF), OFACF-1 ($O_2:F_2$ = 7:3), OFACF-2 ($O_2:F_2$ = 5:5) and OFACF-3 ($O_2:F_2$ = 3:7). The functional group of OFACFs was investigated using X-ray photoelectron spectroscopy analysis. The C-F bonds formed on surface of ACFs. The intensities of the C-O peaks increased after oxyfluorination and increased the oxygen content in the reaction gas. The specific surface area, pore volume and pore size of OFACFs were calculated by the Brunauer-Emmett-Teller and density functional theory equation. Through the $N_2$ adsorption isotherm, the specific surface area and pore volume slightly decreased as a result of oxyfluorination treatment. Nevertheless, the $CO_2$ adsorption efficiency of oxyfluorinated ACF improved around 16 wt% due to the semi-ionic interaction effect of surface modificated oxygen functional groups and $CO_2$ molecules.

• 한국식품위생안전성학회지
• /
• 제35권4호
• /
• pp.304-311
• /
• 2020

Galacto-oligosaccharides(GOS)는 프로바이오틱스 미생물의 성장을 증진시켜 인류 건강에 유익한 작용을 갖게 하는 프리바이오틱스이며 식품 산업에서 다양한 활용성을 갖는다. GOS는 보통 β-galactosidase에 의해 촉매 반응이 일어난 lactose로부터 생성된다. 한편, 세포 표면 발현은 살아있는 세포 표면의 펩타이드와 단백질을 세포의 기능성 성분에 융합시켜 발현시키는 것이다. 표층 발현 세포는 다양한 잠재적 이용가치를 갖는다. N 말단 부근에 위치하는 것으로 생각되는 Flo1p 응집 functional domain은 세포의 flocs로의 가역적인 응집을 유발하면서 α-mannan carbohydrates와 같은 세포벽 성분과 비공유결합을 한다. 한외여과한 유청을 농축, 분무건조한 유청막투과액(Whey Permeate, WP)을 이용하여 β-galactosidase 재조합 Pichia pastoris (P. pastoris) 로 표층 발현 처리 (surface engineering)하는 GOS의 합성법은 폐기물을 활용하는 새로운 효율적인 방법이라 할 수 있다.

• 한국재료학회지
• /
• 제19권3호
• /
• pp.137-141
• /
• 2009

Density functional theory was utilized to investigate the growth of an indium nanowire on a Si (001) buckled surface. A site between the edge of two Si dimers is most favorable when the first In atom is adsorbed on the surface at an adsorption energy level of 2.26 eV. The energy barriers for migration from other sites to the most favorable site are low. When the second In atom is adsorbed next to the first In atom to form an In dimer perpendicular to the Si dimer row, the adsorption energy is the highest among all adsorption sites. The third In atom prefers either of the sites next to the In dimer along the In dimer direction. The fourth In atom exhibited the same tendency showed by the second atom. The second and fourth In adsorption energy levels are higher than the first and third levels as the In atoms consume the third valence electron by forming In dimers. Therefore, the In nanowire grows perpendicular to the Si dimer row on the Si (001) surface, as it satisfies the bonding of the three valence electrons of the In atoms.

• 한국재료학회지
• /
• 제9권1호
• /
• pp.65-72
• /
• 1999

In order to minimize flexible printed circuit(FPC), which is used in computer, communication, medical facility, aviation space industry, it is required to improve the interfacial adhesion of polymide/epoxy or polyimide/polyimide consists of FPC. In this study, it was considered to improve the adhesion strength of polyimide/epoxy joint by introducing functional group on polyimide film and improving mechanical property of epoxy. Functional group on polyimide film was introduced by changing polyimide film surface to polyamic acid in KOH aqueous solution. The optimum conditions for surface modification were the concentration of 1M KOH and treatment time of 5min. Also, the optimum adhesion strength of polyimide/epoxy joint was obtained using rubber modified epoxy and polyamic acid as a base resin and curing agent of epoxy adhesive, respectively. The degree of surface modification of polyimide film examined with contact angle measurement of FTIR, thus modification of polyimide to polyamic acid was identified. Fracture surface of plymide/epoxy joint was analyzed by scanning electron microscopy, and modified polyamic acid reimidezed to polymide as increasing curing temperature.

• KSBB Journal
• /
• 제24권6호
• /
• pp.515-520
• /
• 2009

This study presented facile method of cell patterning using fabricated PDMS patterns on polyelectrolyte coated surface. This basic principle is the fabrication of functional surface presenting two orthogonal surfaces such as cell adhesive and repellent properties. Cell adhesive surface was firstly fabricated with simple coating of polyelectrolyte multilayer. And then, the desired patterns of PDMS for the prevention of nonspecific binding of cells were transferred onto the previously formed thin film of polyelectrolyte multilayer. Thus, we could prepare novel functional surface simultaneously containing PDMS and polyelectrolyte region. As expected, the PDMS regions showed effective prevention of nonspecific binding of cell and the other region, exposed polyelectrolyte area, provided cell adhesive environment. The height of formed PDMS structure was about 100 nm. Based on this method, cell patterning can be successfully obtained with various pattern shapes and sizes. Therefore, we expect that this simple method will be useful platform technology for the development of cell chip, cell based assay system, and biochip.

• 상하수도학회지
• /
• 제8권1호
• /
• pp.34-43
• /
• 1994

It is well known that the adsorption character of activated carbon is dependent on the specific surface area and pore volume, but the relationship between the surface-chemical structure and the adsorption character has not been studied very often. The purpose of this study is to investigate the effect of the acidic surface functional groups of activated carbon and the adsorption characteristics of low concentration phenol. So three types of activated carbons and four different treatments were introduced to this isotherm experiment. These treatments were nontreatment, 1N $HNO_3$ treatment, 6N $HNO_3$ treatment, $H_2O_2$ treatment. The conclusions of this study are as followings. If the initial concentration of phenol is high as 5mg/l, the adsorption is dependent on the specific surface area. If the initial concentration of phenol is low as $100{\mu}g/l$, the adsorption is dependent on the average pore volume. The acidic surface functional groups prevent the adsorption of phenol molecules to activated carbon. And the adsorbed amount decreases more for $HNO_3$ treatment than for $H_2O_2$ treatment and more for concentrated $HNO_3$ treatment than for dilute $HNO_3$ treatment.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
• /
• pp.244-245
• /
• 2017

This study aims to develop high durability graphene / epoxy paint for durability improvement of construction structure. For the development of graphene / epoxy coatings, first, graphene must remain stable in the polymer. Second, the integrity of graphene and polymer should be ensured. Accordingly, in order to obtain dispersibility, surface modification of graphene nanoplate(GnP) with CH and COOH functional groups and its dispersibility in organic solvents were investigated. Also, Fourier Transform Infrared Spectroscopy(FT-IR) analysis and Atomic Force Microscope(AFM) analysis were performed to confirm whether the functional groups were synthesized by surface modification. As a result, FT-IR and AFM analysis did not confirm the surface modification, but GnP was found to be stable when dispersed in an organic solvent.

• 한국연초학회지
• /
• 제31권1호
• /
• pp.9-17
• /
• 2009

Activated carbon fiber (ACF) was surface modified by nitric acid to improve the adsorption efficiency of the propylamine. Functional groups and textural properties of modified ACF were investigated. The total surface acidity increased about 7 times to that of as-received ACF by modification with 1 M nitric acid solution, carboxylic and phenolic groups mainly increased. However, the specific surface areas and the total pore volumes of the modified ACFs were decreased by 5-8% due to the increased blocking (or demolition) of micropores in the presence of newly introduced complexes. Despite the decrease of textural properties, it was found that the amount of propylamine adsorbed by the modified ACFs was increased by approximately 17%. The oxygen and nitrogen contents on the modified ACF increased by 1.5 and 3 times compared with the as-received ACF. From the XPS results, it was observed that propylamine reacted with strong or weak acidic groups, such as -COOH or -OH on the ACF surfaces, resulting in the formation of pyrrolic-, pyridonic- or pyridine-like structures.

• Carbon letters
• /
• 제1권1호
• /
• pp.6-11
• /
• 2000

Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at $900^{\circ}C$. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.