• 접착 및 계면
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• 제11권3호
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• pp.112-119
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• 2010

PMMA와 PBA core 제조 시 개시제는 APS를, 유화제 SDBS의 농도를 0.01에서 0.03 wt% 일 때 전환율이 95.8과 92.3%로 가장 우수하였으며, core-shell 복합입자의 제조 시에는 SDBS의 농도 0.02 wt% 일 때 PMMA/PBA core-shell 복합입자는 전환율이 90.0%, PBA/PMMA core-shell 복합입자는 89.0%가 되었다. FT-IR 분석과 GPC에 의한 평균분자량 측정을 통해 core와 shell 단량체들이 중합되어 있음을 확인하고, 복합입자의 형태는 상온에서의 필름형성정도와 TEM 분석으로 확인하였다. DSC에 의해 유리전이온도를 측정함으로써 일반 공중합체와는 달리 2개의 유리전이온도가 존재하여 core-shell 복합입자가 형성되었음을 알 수 있고, 각각의 core-shell 복합입자의 인장강도와 신율의 측정을 통해 고기능성 접착바인더로서의 사용가능성을 확인하였다.

• Archives of Pharmacal Research
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• 제19권3호
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• pp.235-239
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• 1996

Six, heretofore undescribed, $5^I-Methyl-5^I-(5-Substituted uracil-1-ylmethyl)-2^I-oxo-3^I-methylenetetrahydrofurans(F, Cl, Br, l, CH_3, H)(6a-f)$were synthesized and evaluated against three cell lines (FM-3A, P-388 and U-937). For the preparation of .alpha.-methylene-.gamma.-butyrolactone bearing 5-substituted uracils (6a-f), the effcient Reformatsky type reaction was employed which involves the treatment of ethyl .alpha.(bromomethyl) acrylate and zinc with the respective 5-substituted uracil-1-ylacetones (5a-f). The acetone derivatives (5a-f) were directly obtained by the respective alkylation reaction of 5-substituted uracils with chloroacetone in the presence of $K_{2}$$CO_{3}$(or NaH). These lactone compounds 6a-f exhibited moderate to significant activity in all of the three cell lines, and 6b, 6c and 6e showed significant antitumor activities (inhibitory concentrations ($IC_{50}$) ranged from 1.3-3.8 .mu.g/ml.

• 한국환경과학회지
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• 제14권6호
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• pp.525-532
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• 2005

Polyelectrolyte titration, which was called colloid titration is based on the stoichiometric reaction between oppositely charged polyelectrolytes, This can be used, for instance, to determine the charge density of a cationic polyelectrolyte, using an anionic polyelectrolyte of known charge density, such as potassium polyvinyl sulfate (PPVS). The technique requires a suitable method of end-point detection and there are several possibilities. In this work, two methods have been investigated: visual titrimetry based on the color change of a cationic dye (o-toluidine blue, o-Tb) and spectrophotometry based on the absorbance change corresponding to the color change of the same dye. These have been applied to several cationic polyelectrolytes with different charge density and molecular weight. In all cases, the cationic charge was due to quaternary nitrogen groups. In the case of cationic dye, it was shown that the sharpness depends on the charge density of cationic polyelectrolyte. With the polyelectrolytes of lower charge density, the binding to PPVS is weaker and binding of the dye to PPVS can occur before all of the polyelectrolyte charge has been neutralized. However, by carrying out titrations at several polyelectrolyte concentrations, good linear relationships were found, from which reliable charge density values could be derived. Effects of pH and ionic strength were also briefly investigated. For cationic polyelectrolytes (copolymers of acrylamide and dimethylaminoethy] acrylate), there was some loss of charge at higher pH values, probably as a result of hydrolysis. Increasing ionic strength causes a less distinct color change of o-Tb, as a result of weaker electrostatic interactions.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.162-168
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• 2018

유기 및 무기 폴리실라잔을 우레탄 아크릴레이트와 혼합시킴에 따라 UV 경화형 하드 코팅 용액을 제조하였다. 이용액을 polymethylmethacrylate (PMMA) 시트에 흐름 코팅한 후 UV 경화시킴에 의해 UV 경화형 하드 코팅 도막을 제조하였다. 이 과정 중 폴리실라잔의 종류 및 첨가량을 변화시켜 코팅 도막의 물성에 미치는 영향을 살펴보았다. 그 결과 유기 폴리실라잔의 경우 $95^{\circ}$의 수접촉각을 보여 높은 소수성을 나타내었으며, 7H의 연필경도와 92%의 가시광선 투과율을 보였다. 반면에 무기 폴리실라잔을 코팅한 도막은 8H의 높은 연필경도와 기재와의 우수한 접착력 및 $82^{\circ}$의 수접촉각을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.429-429
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• 2007

In this study, it was investigated about the variation of luminance properties in LED backlight with geometrical shape such as prism or lens shape on the light-entering face. Generally, LED light source has the loss in backlight system because it has horizontal direction light. PMMA(Poly-Methyl-Meta-Acrylate) is used LGP(Light-Guide-Plate) in conventional backlight system. PMMA has low refraction angle. so that. horizontal direction light was not used in backlight system. The addition of geometrical shape in light-entering face in LGP improves the luminance characteristics because it prevents horizontal direction light generation in light-entering-face. Prism or lens shape in same pitch disposition was almost same without these treatment such as the value of 1% rising. Besides. It is particular that the gap of these shape such as the value of 0.407~0.22mm prevents horizontal direction light, so then it contributes luminance rising at 5.6%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.78-80
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• 2006

The hybrid thin-film (HTF) passivation layer composed of the Ultra Violet (UV) curable acrylate layer and MS-31 (MgO:$SiO_2$=3:1wt%) layer was adopted in organic light emitting device (OLEO) to protect organic light emitting materials from penetrations of oxygen and water vapors. The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007gm/m^{2+}day$ at $37.8^{\circ}C$ and 100% RH. This value was within the limited range of the sensitivity of WVTR measurements. And the lifetime of the HTF passivated device became almost three times longer than that of the bare device. The HTF on the OLEO was found to be very effective in protect what from the penetrations of oxygen and moisture.

• 폴리머
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• 제31권2호
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• pp.153-159
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• 2007

생분해성 분자 날인 고분자는 바이오센서 약물 전달 등의 생의학적 분야에 적응이 가능하다. 그러므로, 본 연구에서는 생분해성 고분자인 $poly(\varepsilon-caprolactone)$ (PCL) 매크로머를 가교제로 사용하여 theophylline 분자 날인 고분자를 광중합을 통해 제조하고 물성을 조사하였다. PCL 매크로머는 말단에 아크릴기를 갖도록 합성하였으며 FT-IR과 $^1H-NMR$로 확인하였다. PCL 매크로머의 합성수율은 약 78 mol%였다. Theophylline의 제거 및 재결합 실험은 UV/Vis분광기를 이용하여 용액 내 theophylline의 농도를 확인함으로써 이루어졌다. Theophylline분자 날인 고분자의 생분해성 실험을 $37^{\circ}C$의 PBS 용액 내에서 진행한 결과 우수한 생분해성을 보였다.

• 폴리머
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• 제33권1호
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• pp.45-51
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• 2009

BA와 MMA 그리고 1$\sim$5 wt%/monomer의 다양한 관능성 단량체(AA, 2-HEMA, GMA, AAm)를 사용하여 수용성 아크릴계 점착제를 중합하였다. 점착박리강도를 향상시키기 위해 대기압 평판형 플라즈마 전처리 방식을 피착제에 사용하였다. 관능성 단량체 종류에 따라 AA>2-HEMA>GMA>AAm의 순으로 높은 점착박리강도를 나타내었다. 유지력은 관능성 단량체의 함량이 증가함에 따라 열적 성질이 증가하여 전체적으로 AA>AAm>GMA>2-HEMA순으로 우수한 유지력을 나타내었다. 피착면에 평판형 플라즈마 전처리 방식을 적용한 결과 AA 9.1%, 2-HEMA 9.4%, GMA 9.4%, AAm 1.8%의 후기점착박리강도 증가를 확인할 수 있었다. 결론적으로, 다양한 관능성 단량체와 플라즈마 표면 처리법을 사용하여 점착박리강도, 유지력과 같은 기계적 물성을 조절할 수 있었다.

• Macromolecular Research
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• 제16권6호
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• pp.549-554
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• 2008

Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.

• KSTLE International Journal
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• 제6권2호
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• pp.33-38
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• 2005

Submicron-scale patterns made of polymethyl methacrylate (PMMA) were fabricated on silicon-wafer using a capillarity-directed soft lithographic technique. Polyurethane acrylate (PUA) stamps (Master molds) were used to fabricate the patterns. Patterns with three different aspect ratios were fabricated by varying the holding time. The patterns fabricated were the negative replica of the master mold. The patterns so obtained were investigated for their adhesion and friction properties at nano-scale using AFM. Friction tests were conducted in the range of 0-80 nN. Glass (Borosilicate) balls of diameter 1.25 mm mounted on cantilever (Contact Mode type NPS) were used as tips. Further, micro-friction tests were performed using a ball-on-flat type micro-tribe tester, under reciprocating motion, using a soda lime ball (1 mm diameter) under a normal load of 3,000 mN. All experiments were conducted at ambient temperature ($24{\pm}1^{\circ}C$) and relative humidity ($45{\pm}5\%$). Results showed that the patterned samples exhibited superior tribological properties when compared to the silicon wafer and non-patterned sample (PMMA thin film) both at the nano and micro-scales, owing to their increased hydrophobicity and reduced real area of contact. In the case of patterns it was observed that their morphology (shape factor and size factor) was decisive in defining the real area of contact.