• Carbon letters
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• v.13 no.4
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• pp.230-235
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• 2012

In this study, reduced graphene oxide/polyimide (r-GO/PI) composite films, which showed significant enhancement in their electrical conductivity, were successfully fabricated. GO was prepared from graphite using a modified Hummers method. The GO was used as a nanofiller material for the preparation of r-GO/PI composites by in-situ polymerization. An addition of 20 wt% of GO led to a significant decrease in the volume resistivity of composite films by less than nine orders of magnitude compared to that of pure PI films due to the electrical percolation networks of reduced GO created during imidization within the films. A tensile test indicated that the Young's modulus of the r-GO/PI composite film containing 20 wt% GO increased drastically from 2.3 GPa to 4.4 GPa, which was an improvement of approximately 84% compared to that of pure PI film. In addition, the corresponding tensile strength was found to have decreased only by 12%, from 113 MPa to 99 MPa.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.421-424
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• 2006

Nafion/Pt/Polypyrrole composite membranes were fabricated by chemical in-situ polymerization of pyrrole monomers with Pt precursors in Nafion matrix for DMFC. We demonstrated that positively charged pyrrolinum groups of polypyrrole particles were co-interacted with sulfonic groups of Nafion as verified by FT-IR results. Mutual interaction between $Nafion-SO_3^-$ (or negatively charged Pt precursors) and Polypyrrole$-NH_2^+$ influenced the physical properties of pristine Nafion. Thermal property proton conductivity, methanol permeability, and cell performance of pristine and modified Nafion were analyzed for an application of DMFC membrane. Thermal stabilities of sulfonic groups and side chains in Nafion/Pt/polypyrrole composite membranes were higher than those of Nafion due to mutual interaction between sulfonic groups of Nafion and pyrrolinum groups of polypyrrole. Methanol permeabilities of Nafion/Pt/Polypyrrole composite were reduced more proton conductivities with the increase in the content of Pt particles. As a result of that, the enhancement of cell performance by Nafion/Pt/Polypyrole O2 relative to Nafion was more pronounced under the specific experimental condition such as high temperature and more concentrated methanol solution.

• Textile Coloration and Finishing
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• v.9 no.6
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• pp.68-73
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• 1997

Urea/formaldehyde(UF) and melamine/formaldehyde(MF) microcapsules containing perfume and 2,4,4'-trichlroro-2-hydroxydiphenyl ether(DP) were prepared by the in-situ polymerization using urea and formaldehyde. Effects of dispersing agent, accelerating agent, formaldehyde, agitation speed on the mean diameter of microcapsules were investigated. The diameter of microcapsule was decreased with increasing dispersing agent concentration. A slight increase in the diameter was observed when the concentration of film forming material was increased. The diameter of microcapsule was decreased with increasing agitation speed up to 8,000rpm. The mean diameters of UF microcapsule prepared at 8,000rpm are about 3$\mu$m. A slight decrease in the diameter was observed when the concentration of resorcinol was increased.

• Membrane and Water Treatment
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• v.7 no.6
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• pp.539-553
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• 2016

As a novel hydrophobic monomer, polytetrahydrofuran diacrylate (PTMGDA) was synthesized by the esterification reaction between polyethylene tetrahydrofuran (PTMG) and acryloyl chloride (AC). In situ free radical polymerization reaction method was utilized to fabricate poly (vinylidene fluoride) (PVDF)-PTMGDA-poly(ethylene oxide) dimethacrylate (PEGMA) ulrafiltration (UF) membranes. The performances of PVDF-PTMGDA-PEGMA UF membranes in terms of morphologies, mechanical properties, separation properties and hydrophilicities were investigated. The introduction of the PTMGDA-PEGMA dopants not only increased the membranes' pure water flux, but also improved their mechanical properties and the dynamic contact angles. The addition of the PTMGDA/PEGMA dopants led to the formation of the finger-like structure in the membrane bulk. With the increase concentration of PTMGDA/PEGMA dopants, the porosity and the mean effective pore size increased. Those performances were coincide with the physicochemical properties of the casting solutions.

• Macromolecular Research
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• v.14 no.6
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• pp.610-616
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• 2006

An azoinitiator linked to an epoxy oligomer, which could easily diffuse into the organoclay gallery and swell it, was used as an initiator to enhance the delamination of an organoclay, Cloisite 25A, in a matrix of styrenic polymers, poly(styrene-co-acrylonitrile) and polystyrene, during the preparation of a nanocomposite via an in-situ polymerization method. X-ray diffraction results and transmission electron microscopic observation of the morphology showed that the epoxy segment enhanced not only the delamination but also the extrication of ammonium cations from the organoclay gallery into the polymer matrix. The latter phenomenon induced the structural change of the alkyl group of ammonium cations in the gallery from a bilayer to monolayer structure, and also decreased the glass-rubber transition temperature as measured by a differential scanning calorimeter and dynamic mechanical analyzer.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.1-4
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• 2006

Biodegradable $\beta$-tricalcium phosphate ( $\beta$-TCP)/poly(lactide-co-glycolide) (PLGA) composites were synthesized by in-situ polymerization with microwave energy. The influence of the $\beta$-TCP content in $\beta$-TCP/PLGA composites on the molecular weight, crystallinity, microstructure and mechanical properties was investigated. As the molecular weight of composites decreased, the $\beta$-TCP content increased up to 10 wt.%, while the excess addition of the $\beta$-TCP content above 10 wt.% the molecular weight increased with increasing of the $\beta$-TCP content. This behavior would be due to the superheating effect or nonthermal effect induced by microwave energy. It was found that the bending strength and Young's modulus of the $\beta$-TCP/PLGA composites was proportional to the molecular weight of PLGA. The bending strength of the $\beta$-TCP/PLGA composites ranged from 18 to 38 MPa, while Young's modulus was in the range from 2 to 6 GPa.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.190-193
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• 2002

The processing technology of organic thin-film transistors (Ons) performances have improved fur the last decade. Gate insulator layer has generally used inorganic layer, such as silicon oxide which has properties of a low electrical conductivity and a high breakdown field. However, inorganic insulating layers, which are formed at high temperature, may affect other layers termed on a substrate through preceding processes. On the other hand, organic insulating layers, which are formed at low temperature, dose not affect pre-process. Known wet-processing methods for fabricating organic insulating layers include a spin coating, dipping and Langmuir-Blodgett film processes. In this paper, we propose the new dry-processing method of organic gate dielectric film in field-effect transistors. Vapor deposition polymerization (VDP) that is mainly used to the conducting polymers is introduced to form the gate dielectric. This method is appropriate to mass production in various end-user applications, for example, flat panel displays, because it has the advantages of shadow mask patterning and in-situ dry process with flexible low-cost large area displays. Also we fabricated four by four active pixels with all-organic thin-film transistors and phosphorescent organic light emitting devices.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.3
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• pp.410-418
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• 1994

다양한 유기관능기를 가진 Silane가요제의 기능 양면성과 독특한 화학적 구조는 이들이 면섬유의 물성을 향상시키기 위한 in-situ 중합 및 가교처리의 단량체로 사용될 수 있는 가능성을 시사하므로, 본 연구에서는 이를 위한 기초 실험으로 수용액 상의 silane 단량체의 거동과 in-situ중합의 가능성을 조사하였다. 관능기를 달리하는 methyltriethoxysilane (MES), vinyltriethoxysilane (VES), vinyltriacetoxysilane (VAS)과 epoxy (glycidoxy) propyltrimethoxysilane (EMS) 등이 silane단량체로 선택되었다. Silane수용액의 안정성과 용해도는 단량체의 농도가 증가함에 따라 감소하였으며, pH에 의해서도 크게 영향을 받아 PH 3과 4.5사이에서 가장 안정함을 나타내었다. 10분간의 중기 고착과정에 의해서 충분한 양의 단량체가 면섬유 안으로 확산되었으며, 섬유의 방추성은 반응성이 높은 organotin촉매제를 사용하여 열처리한 후 증가되었다.

• Macromolecular Research
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• v.17 no.1
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• pp.31-36
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• 2009

Highly transparent, thin polythiophene (PT) films were successfully synthesized by the plasma polymerization of thiophene. These films were doped with $O_2$ plasma by in-situ doping technique. The plasma polymerized PT films were deposited at about 50 to 340 nm/min, depending on the temperature and plasma power. A resultant transparency as high as 85% was achieved. The plasma polymerized PT films exhibited the characteristics of an insulator or semiconductor ($10^{10{\sim}12}{\Omega}/{\Box}$, $10^{-7}S/cm$). The conductivity was immediately increased up to $10{\Omega}/{\Box}$ and $10^{-2}S/cm$, when doped with $O_2$ plasma. The plasma-doped PT films exhibited an increased surface roughness resulting in a decreased contact angle. However, the thickness of the PT layer was partially decomposed and/or etched with increasing voltage above 40 W.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.