• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
• /
• pp.197-198
• /
• 2000

A surface-assisted photo-control of the liquid crystal (LC) alignment has been achieved by modifying the topmost surface of the polyimide film with photo-reactive molecules. Recently, photo-alignment technique using a thin film of poly(vinyl cinnamates) have been reported. However their commercial potentiality is limited by their low thermal stability. To enhance thermal stability, we synthesized the chalcone derivatives as the photo-reactive molecules and introduced the materials on the surface-modified polyimide film.. We identified that the photo-chemical reaction of the chalcone derivatives occur in few minutes with irradiation of UV light. The photo-alignment characteristics of the modified polyimide films treated by polarized UV light and their LC cells are investigated as a function of exposure dose.

• Membrane and Water Treatment
• /
• 제1권2호
• /
• pp.103-120
• /
• 2010

Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilic-hydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.115-115
• /
• 2015

Many efforts have been devoted on chemical modification of graphene layer to modulate its electrical properties. In the previous report, laser irradiation on the CYTOP (Amorphous Fluoropolymer) covered graphene layer induces chemical modification wherein carbon fluoride is formed on the graphene surface. This results in the insulating I-V characteristics, which have been attracting much research interests on it. However, the direct analytical evidence of the fluoride formation on graphene surface is not yet studied. In this work we investigated what happened on the CYTOP/graphene interface during photon irradiation using spatially resolved photoemission spectroscopy method. It is found that the soft x-ray (614 eV) induces desorption of fluoride atoms from the CYTOP and change di-fluoride form to mono-fluoride. As the photo-induced fluorine desorption is continue strong dipole field generated by initial di-fluoride forms is gradually decreased, resulting in the overall binding energy shift of the C 1s core levels. Both photo-modified CYTOP and CYTOP starts to desorb above $286^{\circ}C$ (~ 0.047 eV), which means that no strong chemical interaction between CYTOP and graphene is established.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.198.1-198.1
• /
• 2014

Many efforts have been devoted on chemical modification of graphene layer to modulate its electrical properties. In the previous report, laser irradiation on the CYTOP(perfluoropolymer) doped graphene layer induces chemical modification of it, resulting in the insulating I-V characteristics. While the results strongly denoted C-F bond formation after irradiation, the detailed process of photo-induced chemical change is not known yet. To probe this, we utilized synchrotron based SPEM (scanning photoelectron emission spectroscopy) in NSRRC, Taiwan. We irradiate the sample by photon of 614 eV in a stepwise manner as a function of time. As photon irradiation increased, difluoride moieties in the CYTOP was broken, and then formed mono-fluoride with carbon atoms consisting graphene layer.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 춘계학술대회 논문집
• /
• pp.513-514
• /
• 2010

• 한국응용과학기술학회지
• /
• 제15권3호
• /
• pp.47-53
• /
• 1998

The polyimide film surface was modified with KOH aqueous solutions or sulfuric acid. The film thickness was increased by about 10% through the modification of film surface. Hydrolysis of amide bonds and hydration of water induced the increase. The polarity of the film surface increased and identified by contact angle measurement. The depth and roughness of modified was increased. After treatment of surface with water, alkyl and 4-pentyloxyaniline were introduced on the film surface by complex formation between anionic species formed on the imide surface and ammonium ion. The newly introduced alkyl group was identified by FT-IR spectroscopy. Surface polarity reduced dramatically and the roughness was increased after introduction of ammonium salt.

• Korean Chemical Engineering Research
• /
• 제53권5호
• /
• pp.632-637
• /
• 2015

Mesoporous $TiO_2$ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. $TiO_2$ granules obtained showed about 400 nm in size, the specific surface area of $74-77m^2/g$, and average pore size of 13-17 nm. The chemical modification of $TiO_2$ granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (${\eta}=6.72%$) was enhanced about 14% higher than primitive nanoparticles.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.57.1-57.1
• /
• 2010

Development of low cost hybrid functional nano-structured materials has great interest to enhance sensitivity of dye-sensitized solar cells and reduction of the production cost. In this talk we will discuss about using different processes to modify functional characteristics of photoelectrode and investigate effects of chemical modification without significant structural variation on to enhance performance of DSSCs. Efficient electron transportation between dye molecules and photoelectrode has been obtained by appropriate chemical modification and efficiency of DSSC has been significantly improved. A comparative analysis on effects of surface functional and electron states of photoelectrode on VOC and JSC has been also carried out to discuss effects of composite materials on physical structure and electronic properties to correlate enhanced performance of these devices.

• 한국전기전자재료학회논문지
• /
• 제24권5호
• /
• pp.398-403
• /
• 2011

Recently, Near-infrared (NIR)colorant is intriguing and attractive but full of challenges. Although some cyanine colorant have been commercialized, near-infrared colorant with intensive NIR absorption, good chemical and photo-stability, and high solubility still remain as target compound. Certain polycyclic aromatic compounds such as quaterrylene represent a key class of NIR colorant and also give rise to outstanding physical and chemical properties after appropriate chemical modification. In this study, We have tried to introduceimide functional group to quaterrylene in order to give chemical and thermal stability. Finally, N,N'-bis (2,6-diisopropylphenyl)-quarterrylene-3,4:13,14-tetracarboximide was synthesized and evaluated its properties using $^1H$ NMR, Maldi-tof, TGA, and UV/VIS/NIR spectroscopy as NIR colorant. The quaterrylene bisimide compound exhibit a excellent thermal stability and chemical stability.

• Korean Chemical Engineering Research
• /
• 제43권1호
• /
• pp.1-8
• /
• 2005

본 연구에서는 광촉매의 광자효율을 증가시키고, 물성을 변화시켜 광촉매 성능을 향상시키기 위하여, 자동차 폐 촉매에서 추출된 귀금속 용액 또는 $H_2PtCl_6$ 용액을 수열합성법에 의해 제조된 $TiO_2$와 상업용 $TiO_2$인 P-25(Degussa Co.)를 함침시켜 변조된 광촉매를 제조하였다. 그리고 변조된 광촉매는 ICP-AES, EDS, UV-DRS, XRD, XANES, SEM에 이용하여 물성분석 하였다. 그리고 폐 자동차 촉매전환기의 추출용액을 함침시킨 광촉매를 변조하여 band-gap energy를 1.76eV(705 nm)의 가시광 영역까지 조절하였다. 변조된 광촉매는 PVC가 주성분인 벽지 코팅제와 농도별로 혼합하여 광화학반응을 위한 기능성 도료를 제조하였다. 이 도료를 사용하여 광촉매가 코팅된 기능성 벽지를 제조하였으며, 제조된 벽지의 광촉매 성능을 평가하였다. 반응모델 물질로 NO를 이용하여 촉매 조성, 반응물 농도, 벽지의 촉매 담지량, 반응시간에 따른 광 화학반응속도를 측정하였다. 그 결과 폐 자동차 촉매전환기의 추출용액으로 변조된 $TiO_2$의 광촉매 활성이 크게 증가하였음을 알 수 있었고 그 중에서도 P-25에 추출용액을 함침시킨 P-25(w)의 광촉매가 가장 우수한 광촉매활성도를 나타내었다.