• Macromolecular Research
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• 제17권7호
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• pp.506-515
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• 2009

We synthesized a series of polystyrene derivatives containing various side chain terminal moieties, such as phenoxymethyl, 4-methoxyphenoxymethyl, 4-fluorophenoxymethyl, 4-methylphenoxymethyl, and 4-trifluoromethoxyphenoxymethyl groups, using polymer analogous reactions, in order to investigate the effect of the side group on their liquid crystal (LC) alignment behaviors. The polymers containing 4-fluorophenoxymethyl, 4-methylphenoxymethyl, or 4-trifluoromethoxyphenoxymethyl side groups had lower surface energy values and the LC cells fabricated using the unrubbed films of these polymers showed homeotropic LC alignment behavior. The LC cells fabricated using the rubbed films of the polymers containing phenoxymethyl or 4-fluorophenoxymethyl groups showed homogeneous planar LC alignment behavior in which the LCs were aligned perpendicular to the rubbing direction. This homogeneous planar and perpendicular alignment behavior was ascribed to the favorable anisotropic interactions between the LC molecules and the side groups preferentially oriented perpendicular to the rubbing direction.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.123-125
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• 1996

The orientation effect of galactose ligand on hepatocyte attachment was investigated. Poly(N-p-vinyl benzyl-o-${\beta}$-D-galactopyranosyl-D-gluconamide) (PVLA), a ${\beta}$-galactose-carrying styrene homo-polymer, was used as a model ligand for the asialoglycoprotein receptors on hepatocytes. PYVA was transferred onto the poly(${\gamma}$-benzyl L-glutamate)(PBLG) or PBLG/ poly(ethylene glycol)(PEG)/PBLG Langmuir-Blodgett (LB) films as the monolayer level. The dichroic fluorescence values of confocal microscope indicated that the PVLA transferred onto the LB films was located with a preferential orientation of its molecular axes with regard to the direction of the a-helix of polypeptide. Hepatocyte recognized well-oriented galactose moieties of the surface of PVLA through asialoglycoprotein receptors.

• 폴리머
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• 제35권3호
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• pp.272-276
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• 2011

선택 반사를 보여주는 콜레스테릭 액정의(cholesteric liquid crystal; CLC) planar 배열이 유도되는 메카니즘을 CLC 셀의 선택 반사율과 FTIR $C{\equiv}N$ 피크 세기를 측정하여 조사하였다. 배향막을 사용한 경우보다는 planar 배열 유도가 완전하지는 않았지만 shear force를 이용하거나 또는 고분자 기판을 연신하여 배향막을 사용하지 않은 상태에서 planar 배열을 유도하였다. CLC의 planar 배열이 유도되는 메카니즘은 기판 표면에 접촉하는 액정분자들이 한 방향으로 늘어서면, 그 액정분자 위에 CLC의 나선 구조들이 기판에 수직으로 형성되며 planar 배열이 유도되는 것이다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.300-300
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• 2006

Nondestructive nanostructural analysis is indispensable in the development of nano-materials and nano-fabrication processes for use in nanotechnology applications. In this paper, we demonstrate for the first time a quantitative, nondestructive analysis of nanostructured thin films supported on substrates and their templated nanopores by using grazing incidence X-ray scattering and data analysis with a derived scattering theory. Our analysis disclosed that vertically oriented nanodomain cylinders had formed in 20-100 nm thick films supported on substrates consisting of a mixture of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) and PMMA homopolymer, and that the PMMA nanodomains were selectively etched out by ultraviolet light exposure and a subsequent rinse with acetic acid, resulting in a structure consisting of hexagonally packed cylindrical nanopores.

• 폴리머
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• 제27권4호
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• pp.313-322
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• 2003

상용화제와 교환반응 촉진제 도입에 따른 폴리(에틸렌 테레프탈레이트) (PET)/폴리(메타-자이렌 아디프아미드) (MXD-6) 블렌드의 형태구조 변화와 일축 연신한 블렌드 시료의 변형 형태구조를 조사하였다. 연신시료는 피브릴 구조의 분산상을 보여주었으며, 피브릴 구조는 연신비 증가에 따라서 점차 미세하게 변형되었다. 교환반응 촉진제나 상용화제의 첨가는 계면 접착력 향상에 기여하기보다는 분산상과 연속상 간에 결함을 야기함으로써 피브릴 구조의 균일성을 감소시켰다. H$_{v}$ 모드의 광산란을 이용하여 블렌드 조성과 연신비에 따른 고차구조 변화를 알아보았다. H$_{v}$ 산란패턴으로부터 결정들이 스택을 이루며, 스택은 연신 방향에 대하여 특정한 각도로 배향됨을 알 수 있었다. 분산상과 연속상 내의 결정은 연신비 증가에 따라서 점진적으로 배향되어, 연신비가 6.0인 경우에는 매우 높은 배향 수준을 보여주었다.

• 접착 및 계면
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• 제14권4호
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• pp.175-182
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• 2013

본 논문에서는 고상압출된 폴리프로필렌/탄산칼슘 복합재료의 배향 전후의 비중, 열적 및 기계적 물성의 변화에 대해 연구하였다. 본 연구를 위해 두 가지 다른 크기를 갖는 탄산칼슘 충진제(OM-1 및 OM-10)를 폴리프로필렌에 첨가하여 폴리프로필렌/탄산칼슘 복합재료를 제조하였다. 충진제의 함량이 증가할수록 복합재료의 비중이 증가하였는데, 배향된 복합재료의 비중은 배향되지 않은 복합 재료에 비해 작은 것으로 나타났으며 이는 배향에 따라 발생된 미세공극으로 기인한 것이다. 배향 시 발생하는 이 미세공극은 복합재료의 인장 및 굴곡 물성에 큰 영향을 미치는 것으로 밝혀졌다. 굴곡강도 및 굴곡 탄성률에 미치는 배향의 영향은 충진제의 입자 크기에 상관없이 충진제의 함량의 영향보다 더 강한 것으로 나타났다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.84.1-84.1
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• 2010

Since the discovery of the carbon nanotube(CNTs), they have attracted much attention because of unique properties that may impact many fields of science and technology. The considerable properties of CNTs include high surface area, outstanding thermal, electrical conductivity and mechanical stability. However, uniform deposition of Pt nanoparticles on carbon surface remains inaccessible territory because of the inert carbon surface. In this study, we prepared directly oriented CNTs on carbon paper as a catalyst support in cathode electrode. carbon surface was functionalized using aryl diazonium salt for increasing adhesion of Ni particles which is precursor for growing CNTs. For fabricate electrode, CNTs on carbon paper were grown by chemical vapor deposition using Ni catalyst and Pt nanoparticles were deposited on CNTs oriented carbon paper by polyol method. The performance was measured using Proton electrolyte Membrane Fuel Cell(PEMFC). The structure and morphology of the Pt nanoparticles on CNTs were characterized by Scanning electron Microscopy(SEM) and Transmission electron Microscopy (TEM). The average diameter of Pt nanoparticles was 3nm.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.351-354
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• 2015

In this study, alumina plates 9~25 μm in size were used as thermal fillers, and epoxy resin was used as a polymer matrix. Oriented alumina plate/epoxy composites were prepared using a rolling method. The effect of ordering alumina plates increased with alumina plate size. The thermal conductivity and flexural strength of the composites were investigated. The horizontal thermal conductivity of the oriented composite was significantly higher than the vertical thermal conductivity. The horizontal thermal conductivity of the 75 wt% alumina content was 8.78 W/mk, although the vertical thermal conductivity was 1.04 W/mk. Ordering of the alumina plate using a rolling method significantly improved the thermal conductivity in the horizontal direction. The flexural strengths of the ordered alumina/epoxy composites prepared at different curing temperatures were measured.

• Steel and Composite Structures
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• 제21권4호
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• pp.921-947
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• 2016

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

• 폴리머
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• 제27권4호
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• pp.323-329
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• 2003

기능성 도핑제인 di(2-ethylhexyl) sulffsuccinate sodium salt (NaDEHS)을 사용하여 화학적, 전기화학적 방법에 의한 연신성 폴리피롤을 합성하였다. 화학적, 전기화학적 방법에 의해 제조된 폴리피를 필름은 구역 연신 방법을 사용하여 1.0∼2.5배 연신시킬 수 있었으며, 연신된 폴리피를 필름의 전기 전도도를 측정하였다. 연신율이 증가함에 따라 필름의 전기 전도도는 증가함을 볼 수 있었다. 이러한 현상은 연신율에 따른 결정성 증가로 설명할 수 있었다. 온도변화에 따른 전하 이동 경로는 1.0-2.0배 연신된 폴리피롤의 경우 3차원 variable range hopping모델, 2.5배 연신된 폴리피롤의 경우 1차원 VHR모델에 적합함을 볼 수 있었다.