• Clean Technology
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• v.22 no.3
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• pp.203-207
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• 2016

Here, we report a novel fabrication technique for patchable organic lasing sheet based on non-volatile liquid organic semiconductors and freestanding polymeric film with high flexibility and patchability. For this work, we have fabricated the second-order DFB grating structure, which leads to surface emission, embedded in the freestanding polymeric film. Using an ultra-violet (UV) curable polyurethaneacrylate (PUA) mixture, the periodic DFB grating structure can be easily prepared on the freestanding polymeric film via a simple UV curing process. Due to unsaturated acrylate remained in the PUA mixture after UV curing, the freestanding PUA film provides adhesive properties, which enable mounting of the patchable organic lasing sheet onto non-flat surfaces with conformal contact. To achieve laser actions in the freestanding resonator structure, a composite material of liquid 9-(2-ethylhexyl)carbazole (EHCz) and organic laser dyes was used as the laser medium. Since the degraded active materials can be easily refreshed by a simple injection of the liquid composite, such a non-volatile liquid organic semiconducting medium has degradation-free and recyclable characteristics in addition to other strong advantages including tunable optoelectronic responses, solvent-free processing, and ultimate mechanical flexibility and uniformity. Lasing properties of the patchable organic lasing sheet were also investigated after mounting onto non-flat surfaces, showing a mechanical tunability of laser emission under variable surface curvature. It is anticipated that these results will be applied to the development of various patchable optoelectronic applications for light-emitting displays, sensors and data communications.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.141-145
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• 2005

Since the electromagnetic properties of fiber reinforced polymeric laminate composite can be tailored effectively by adjusting its composition and regulating the stacking sequence, it is plausible material for fabricating the radar absorbing structures (RAS) of desired performance. In order to design the effective electromagnetic wave (EM) absorber with the fiber reinforced polymeric laminate composite, its electromagnetic characteristics should be available and could be regulated easily in the target frequency bands. In this study, dielectric characteristics of the E-glass/epoxy laminate composites were measured by the free space method in the X-band frequency range ($8.2\;{\sim}\;12.4\;GHz$). In order to describe the dielectric behavior of laminate composites of arbitrary stacking sequences, the equivalent circuit model and the laminating equations for estimating dielectric properties were proposed, and experimentally verified. From the comparison of the predicted and measured data, the proposed method predicted well the experimentally measured data.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1271-1282
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• 1994

The surface of commercial alumina fibers used for reinforcing the MCFC matrix has been coated with ${\gamma}$-LiAlO2 being the same material as the matrix, by the sol-gel method in order to enhance the corrosion resistivity of alumina fibers. Stable LiAlO2 complex polymeric sols for coating was synthesized by mixing aluminum alkoxide polymeric sols with LiNO3 solution. It was found that the LiAlO2 polymeric sol prepared by adding the mixed chelate of acethylacetone and triethanolamine (the mole ratio of AA/TEA = 0.125/0.75) to the 1 mole of the aluminum alkoxide had the excellent stability and coating behavior. The crystalline structure of the dried gel from the ${\gamma}$-LiAlO2 sol was completely transformed into the ${\gamma}$-LiAlO2 at $600^{\circ}C$. The optimum viscosity of the sol for coating the alumina long fibers was 30~40 cP, while it was 12~20 cP in case of the short fiber coating. The ${\gamma}$-LiAlO2 coated alumina fibers without defects fully densified when heat-treated at 120$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.151-158
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• 1999

$\varepsilon$-Caprolactame as organic monomer was intercalated in the interlayer space of montmorillonite and polymerized by polymerization reaction so that the inorganic polymer and organic polymer could be combined each other by chemical bonding. The results of X-ray and IR analysis showed that the polymerization reaction of $\varepsilon$-caprolactame between the interlayer spaces has been performed sucessfully. In order to study polymeric reaction product in detail we have isolated the polymerized material from the interlayer space and analyzed it by X-ray diffractometer and IR-Spectrocopy. The comparison of these results with them of the analyses for thee pure polymer which has been synthesized by polymeric reaction of $\varepsilon$-carolactame without montmorillonite showed that the obtained both polymeric materials are the same compounds.

• Journal of Adhesion and Interface
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• v.3 no.1
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• pp.13-19
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• 2002

We have studied on the surface and adhesion properties for acrylic terpolymers, having both hydrophobic and hydrophilic side chains, synthesized via solution polymerization. In order to develop a waterborne material. we tried to synthesize these terpolymers via emulsion polymerization. The polymeric emulsion synthesized was mainly composed of methyl methacrylate (MMA), methoxy-polyethyleneglycol methacrylate (MPEGMA) having hydrophilic side chains and methoxypolypropyleneglycol methacrylate (MPEGMA) having hydrophobic side chains. The viscosities of this series increased with an increase in the content of the co-monomer such as MPEGMA and (MPEGMA). This behavior resulted in the increase in the diameter and heterogeneity of the emulsion particle via AFM observation. Furthermore. the tensile adhesion strength and 90-degree peel strength of the adhesive of these polymeric emulsions were measured. In the case of polymeric emulsion composed of the same content of both hydrophilic and hydrophobic component, the adhesion property showed the highest value. However, since the adhesion properties as a practical applicable adhesive were poor, some improvements were required. When the composition above was modified with butyl acrylate (BA), the improvement effect on adhesion strength was accepted. In particular, 90-degree peel strength increased up to a maximum of 400% of the original value.

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.487-500
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• 1998

A bird's-eye view on preparation, structure and properties of polymeric complexes in the field of Inorganic-Organic-Hybrids is presented in the view point of solid state and materials chemistry. These materials are useful precursors for preparing nanoparticles and fine grain oxides. Some of them are electroactive and are used as protonic or lithium electrolytes, electrochromic materials or membranes for sensors and actuators. New results on bio-hybrids, a class of material not far from polymeric complexes, are also described.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.631-632
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• 2011

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.121-126
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• 2010

The automotive weather strip has functions of isolating of water, dust, noise and vibration from outside. To achieve good sealing performance, weather strip should be designed to have the high contact force and wide contact area. However, these design causes excessive permanent deformation of weather strip. The causes of permanent deformation is generally explained to be the chemical material detrioration and physical variation and cyclic loading, etc. This paper introduces a numerical method to predict the permanent deformation using the time dependent viscoelastic model which is represented by Prony series in ABAQUS. Uniaxial tension and creep tests were conducted to obtain the material data. And the lab. test for the permanent deformation was accelerated during shorter time, 300 hours. The permanent deformation of weather strip was successfully predicted under the different loading conditions and different section shapes using the suggested numerical process.

• Polymer(Korea)
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• v.30 no.6
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• pp.550-555
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• 2006

The coating material for the ink-jet printing paper tends to be waterbase as the waterbase ink-jet ink is used more widely. Waterbase coating material consists of alumina sol as a pigment, poly(vinyl alcohol) as a main binder and polymeric additive for improving properties. In this study, polymeric auditive was synthesized by combining one or toto monomers among methacrylic acid, acrylic acid and acrylamide to the basic monomers, styrene and n-butylacrylate. The properties of printability such as ink absorption, ink spreading, and optical density, glossiness and water resistance were investigated by changing the kinds of surfactants, the composition of monomers and the structure of polymer particles. Results showed that materials containing anionic surfactant and/or acrylic acid had problems in com-patibility with alumina sol. Also, coating materials containing acrylamide had good printability and lout glossiness while those containing methacrylic acid did not have good printability and high glossiness.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1249-1250
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• 2004

In this paper, we report new technique of preparation of material for flexible displays and E-paper technology. This material represents porous polymeric fiber based on polyacrylonitrile filled by liquid crystal.