• Macromolecular Research
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• 제9권5호
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• pp.285-291
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• 2001

The polysulfone(PSf)/polyethersulfone(PES) blend membranes were prepared by an immersion precipitation method. N-methyl-2-pyrrolidone(NMP) was used as a solvent and water as a nonsolvent. The composition of the coagulation bath and the dope polymer concentration as well as the blend ratio of two polymers were varied. The membrane morphologies were interpreted on the basis of the phase diagram of the PSf/PES/NMP/water system. As the solvent content in the coagulation bath increased in the single polymer system, the number of macrovoids decreased and the morphology was changed from finger-like to cellular structure. In the given bath condition phase separation occurs earlier for the solutions of PSf/PES blend than for those of single polymer. A horizontally layered structure and horizontal protuberances inside the macrovoid were observed for the membranes formed from PSf/PES blend solutions. This peculiar structure formation can be interpreted by a PSf-rich/PES-rich phase separation followed by a polymer-rich/polymer-lean phase separation during the exchange of solvent and nonsolvent.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.2079-2082
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• 2007

Photonic crystals containing rugate structure result in a mirror with high reflectivity in a specific narrow spectral region and are prepared by applying a computer-generated pseudo-sinusoidal current waveform. Well defined 1-dimentional photonic polymer replicas showing a reflectivity at 534 nm have been successfully obtained by the removal of rugate porous silicon (PSi) template from the polystyrene composite film. XRD measurement indicates that the oxidized rugate PSi has been completely removed from the composite films. Polymer replicas exhibit a sharp resonance in the reflectivity spectrum. Optical characteristics of photonic polymer replicas indicate that the surface of polymer film has a negative structure of rugate PSi. These replicas are stable in aqueous solutions for several days without any degradation. The methods have been provided for the construction of photonic structures with polymers.

• Macromolecular Research
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• 제9권1호
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• pp.66-70
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• 2001

In this work, we present the development of phase structure of the poly(methyl methacrylate)(PMMA)/ poly(vinylacetate)(PVAc) mixtures in ethyl acetate solution by light scattering. The PMMA/PVAc blends cast from ethyl acetate solutions exhibited fine "modulated structures" over broad blend composition ranges, which originated from the spinodal decomposition of the ternary polymer solutions at low polymer concentrations during the casting. The periodic distance was depended on the blend compositions and evaporation times.

• 폴리머
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• 제25권5호
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• pp.754-758
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• 2001

Vesicle을 단량체가 중합 반응을 할 수 있는 장소로 사용하기 위하여, vesicle 내의 소수성부분에 단량체와 가교제를 집어넣었다. 즉 dimethyldioctadecylammonium bromide를 증류수 속에서 초음파 분산을 하여 vesicle을 만든 후, 여기에 styrene과 divinylbenzene을 첨가한 다음 AIBN으로 중합시켰다. 형성된 고분자는 남겨두고 vesicle을 형성하였던 계면활성제들을 모두 에탄올로 추출해서 제거하여 순수 고분자로 이루어진 구형의 구조물을 얻었다. 그리고 methyl methacrylate와 ethylene glycol dimethacrylate를 이용해서도 고분자로 이루어진 구형의 구조물을 합성하였다.

• Fibers and Polymers
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• 제5권2호
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• pp.83-88
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• 2004

In order to assess the potential of the hydroxy-containing polyamic acid (PHAA) synthesized from 3,3'-dihydroxy benzidine and pyromellitic dianhydride for a fire-safe polymer, the cyclization pathway of PHAA has been investigated using a model compound prepared from 2-aminophenol and phthalic anhydride. The reaction was monitored. by $^1{H-nuclear}$ magnetic resonance. N-(2-hydroxyphenyl) phthalamic acid is converted to N-(2-hydroxyphenyl) phthalimide at ca. 175$^{\circ}C$, showing endothermic reaction. The imide structure is rearranged to the benzoxazole structure over ca. $400^{\circ}C$. These results are similar with that of PHAA. According to pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) data, water and carbon dioxide are released during the cyclization and rearrangement reaction. One DMAc molecule is complexed with one carboxyl acid group in PHAA, which accelerates the imidization process to release more easily the flame retardant, water.

• Fibers and Polymers
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• 제7권3호
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• pp.217-222
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• 2006

Propargyl alcohol was coupled to 2,4-hexadiyne-1,6-diol (HDD) and crystallized in the process of ultraviolet irradiation-induced topochemical polymerization. The HDD polymer crystals were used as one component in the fabrication of organic photovoltaic cells, in combination with fullerene as the electron acceptor. The various structures of the produced photovoltaic cells included bilayer, trilayer, and bulk heterojunction structures. Their photovoltaic properties were analyzed in relation to crystal structure, electrochemical properties, and band structure of the HOD polydiacetylene polymers.

• 폴리머
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• 제24권5호
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• pp.682-689
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• 2000

고분자의 구조설계를 통해서 단상의 블렌드를 제조하기 위해서는 고분자 반복 단위간의 열역학적 정보가 필수적으로 요구된다. 본 연구에서는 블렌드를 구성하는 각 성분간의 상호작용 에너지를 결정하고 이를 이용하여 단상의 블렌드를 제조하는 방법을 제시하였다. 이를 위하여 폴리카보네이트들과 여러 종류의 폴리메타크릴레이트간의 상용성을 조사하였으며, 이를 바탕으로 고분자 구조를 조절하여 단상의 블렌드를 제조하였다. 또한 단상의 블렌드에 포함된 각 고분자간의 상호작용 에너지는 LCST 거동에 의한 상분리 온도와 상태방정식을 이용하여 정량화 하였다.

• Elastomers and Composites
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• 제54권1호
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• pp.30-34
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• 2019

Four different diisocyanates (IPDI; isophorone diisocyanate, HDI; hexamethylene diisocyanate, HMDI; dicyclohexylmethane-4,4'-diisocyanate, and XDI; m-xylylene diisocyanate) were used to prepare polyurethane gel-coats, and the weatherabilities, physical properties, and surface characteristics of the gel-coats were investigated with respect to the chemical structure of the diisocyanates. The weathering test results indicated that all of the diisocyanates used in this study were suitable for use in the preparation of the polyurethane gel-coat. However, the set-to-touch times and physical properties of the polyurethane gel-coat indicated that the cycloaliphatic diisocyanate (IPDI and HMDI) were ideal for the preparation of polyurethane gel-coats.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술논문발표회
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• pp.31-36
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• 2002

Recently, more interests in surface treatment of structure with water repellent agent are steadily increased, But, investigation of its properties such as protection, durability, morphology of micro structure is not sufficient. Therefore, This paper is aimed for the investigation of water repellent property and change of morphology of micro pores in mortar that is treated by water repellent agent(Inorganic polymer based material). Water repellent property, water absorption coefficient, air permeability, porosity and the observation of micro structure was investigated in different water repellent agent type. The test results indicated that water repellent treated mortar showed low absorption coefficient and air permeability(breathing effect). This is why inorganic polymer is coated at the wall of capillary and micro pores, also, the volume of micro pore is reduced without the change of morphology in micro structure.

• 한국응용과학기술학회지
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• 제23권4호
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• pp.290-299
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• 2006

This article investigated to polymer-clay nanocomposite, especially in interfacial respect clay structure, its dispersion into polymer matrix, and clay modification is studied. The cationic exchange of surfactants with clay gallery results in preparing organo-clay capable of compatiblizing to monomer or polymer and increasing interlayer adhesion energy due to expansion of interlayer spacing. The orientation of surfactant in clay gallery is affected by chemical structure and charge density of clay, and interlayer spacing and volume is increased with alkyl chain length of surfactant, or charge density of clay. Also, the interaction between clay and polymer in preparing polymer-clay nanocomposite is explained thermodynamically. In the future, the study and development of polymer-clay nanocomposite is paid attention to the interfacial adhesion, clay dispersion within polymer, mechanism of clay intercalation or exfoliation.