• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.803-805
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• 2009

A highly efficient blue organic light-emitting diode (OLED) was fabricated by using a novel polymer host, poly[3-(carbazol-9-ylmethyl)-3-methyloxetane]. The resultant solution-processed device showed a markedly high efficiency of 29.7 lm/W at 100 cd/$m^2$ by doping 24 wt% blue dye bis(3,5-difluoro-2-(2-pyridyl)-phenyl-(2-carboxy pyridyl) iridium (III).

• Journal of Environmental Science International
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• v.28 no.5
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• pp.503-509
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• 2019

To prevent environmental pollution caused by leakage of leachate from waste landfill, vinyl acetate-ethylene (VAE) resin is applied to liner and cover materials to improve their performance. Styrene, styrene butadiene rubber, and VAE are widely used as polymer resins that have excellent water resistance and durability. Further, VAE resin is known to have additional advantages such as adhesion to nonpolar materials and resistance to saponification as a copolymer. In this study, the effect of VAE content on the properties of liner and cover materials was studied. The water and air content ratios, bending and compressive strengths, water absorption ratio, and coefficient of permeability of these materials were measured. The liner and cover materials with 4 wt% VAE showed good properties.

• Polymer(Korea)
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• v.30 no.2
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• pp.97-107
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• 2006

In spite of excellent thermomechanical performance the majority of aromatic polyimides are so poor in processability due to their high backbone rigidity that their applications are greatly limited. The introduction of long side chains not only enhances their processiblity but also makes useful contribution to discovering new application fields. In this article, a variety of novel aromatic polyimides with flexible side chains were prepared either from new dimines or new dianhydrides to measure the influence of the side chains on structure and properties of the polymers and their new applications as liquid crystal alignment layers, photosensitive polymers, alternating multilayer nano-films and photoluminescent materials are discussed.

• Macromolecular Research
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• v.12 no.5
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• pp.528-533
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• 2004

We have prepared amide dendrons having alkyl peripheral units and various focal moieties through a convergent synthetic approach. The amphiphilic properties, due to hydrophilic amide branches and the hydrophobic peripheral units, provide an opportunity for the amide dendrons to self-organize in water. The dendritic architecture itself is also one of the critical factors in the self-organization of the amide dendrons in water. In particular, function-alization was performed at the focal point to elucidate the relationship between the focal functionality and the self-organized structures of the dendritic building blocks in the aqueous phase. The dendron having a short poly(ethylene glycol) monomethyl ether (MeO-PEG) unit (M$\_$n/ =750) as the focal moiety formed a vesicular organization in water. As the size of the hydrophilic focal MeO-PEG increased to M$\_$n/ =2,000 and 5,000, the self-organized structures became rod-type and spherical micelles, respectively. Our observation of multiple morphologies for amide dendrons is in good agreement with previous reports that indicated that the micellar structures changed from vesicles to rod-types and then to spheres upon increasing the size of the hydrophilic moiety of the amphiphiles.

• Polymer(Korea)
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• v.37 no.5
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• pp.563-570
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• 2013

Poly(vinyl pivalate) (PVPi) was bulk polymerized to make poly(vinyl alcohol) (PVA) microfibrils to apply for polymeric embolization coils replacing metalic coils. Then, syndiotactic PVA (s-PVA) microfibrils having number-average degree of polymerization of 1100 and s-diad content of 60.4% were prepared via saponification of the PVPi with no separate spinning process. To make s-PVA microfibrils with radiopacity, zirconium dioxide ($ZrO_2$) and barium sulfate ($BaSO_4$) were added into s-PVA microfibrils during saponification. The computed tomography (CT) value indicating radiopacity reached up to over 1000 when the amount of $ZrO_2$ and $BaSO_4$ were 12 and 6 wt%, respectively.

• Carbon letters
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• v.12 no.2
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• pp.85-89
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• 2011

Coloured wastewater is released as a direct result of the production of dyes as well as from various other chemical industries. Many dyes and their breakdown products may be toxic for living organisms. Activated carbon is one of the best materials for removal of dyes from aqueous solutions. The present study describes the adsorption behaviour of methylene blue dye on three microporous activated carbons, where two samples (AC-1 and AC-2) were prepared by a polymer blend technique and the other is a microporous activated carbon (ARY-3) sample from viscose rayon yarn prepared by chemical-physical activation. The effects of contact time and activated carbon dosage on decolourisation capacity have been studied. The results show that activated carbon having mixed microporosity and mesoporosity show tremendous decolourisation capacity for methylene blue. In addition, the activated carbon in the powder form prepared by the polymer blend technique shows better decolourisation capacity for methylene blue than the activated rayon yarn sample.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.338-338
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• 2006

Equilibrium behavior of ABA triblock copolymer with different lengths of endblock A chains was examined using self-consistent field theory by Matsenl. It was found that at small asymmetries, the A block bidispersity reduces the stretching energy of the A domains. This effect causes a slight increase in the domain spacing and shifts the order-order transitions toward higher A volume fractions. At large asymmetries, the short A blocks pull free of their domains allowing their B blocks to relax. A feature of microphase-separated structure of asymmetric poly(methyl acyrylate) (PMA)-b-polystyrene-b-PMA using SAXS, DSC and ESR was experimentally examined. These measurements gave an evidence of the solubilization of short A chains to the B domains.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.171-171
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• 2006

In this presentation, we would like to report an inkjet printing method to produce 1 to 2 bit RFID tag working in the range of 6 to 28 MHz with or without transistors. The inkjet printing method especially for the formation of transistors, inductors, capacitors will be presented by the view of polymer chemistry. This presentation also includes the printing schemes for memory cell, ring oscillator, rectifier, antenna, and so forth for constructing RFID tag. I illustrate these strategies by describing recent my works on the formation of all SWNT-TFT and conducting polymer-silver nanocomposite inks that can be applied in the construction of electronic devices.

• Composites Research
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• v.29 no.4
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• pp.186-193
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• 2016

The development of electrospun nanofibers with improved mechanical properties is of great scientific and technological interest because of their wide-range of applications. Reinforcement of carbon nanotubes (CNTs) into the polymer matrix is considered as a promising strategy for substantially enhancing the mechanical properties of resulting CNTs/polymer composite mats on account of extraordinary mechanical properties of CNTs such as ultra-high Young's modulus and tensile strengths. This paper summarizes the recent developments on electrospun CNTs/polymer composite mats with an emphasis on their mechanical properties.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1616-1622
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• 2001

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.