• Polymer(Korea)
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• v.36 no.4
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• pp.536-541
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• 2012

The effects of silica content were studied on UV curing characteristics and defect formations in imprinted patterns of hundreads nanometer size for the photo-curable imprinting composites with silica particles. An increase in elasticity and a decrease in shrinkage were observed with an increase in silica content in the imprinting resin which was UV cured at room temperature. However, the patterned nano-pillars were stuck together with neighboring nano-pillars if the amount of silica is more than 7 wt%. This can be ascribed to the increased viscosity of imperfectly cured resin due to the obstruction of the photo-reaction by silica particles. Addition of silica to the imprinting resin is useful in enhancing the strength of the cured resin although it is difficult to get good imprinted patterns for the resin with more than 7 wt% of silica due to the reduction of photo-reaction conversion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.187-187
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• 2009

The PVA(patterned vertical alignment) mode has a excellent dark state at normal direction. but they has a disclination area at divided domain region at voltage on state. so this disclination make a slow response time and decrease transmittance. To overcome this problem, we research about polymer stabilized vertical alignment (PS-VA) method which was using the UV curable reactive mesogen. According to our research, UV exposure condition which was UV dosage condition effected to rising time and decay time and also threshold voltage.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.40-44
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• 2008

The interfacial adhesion energy between resist and a substrate is very important due to resist pull-off problems during separation of mold from a substrate in nanoimprint process. And effect of substrate surface roughness on interfacial adhesion energy is very important. In this paper, we have treated glass wafer surface using $CF_4$ gas for increase surface roughness and it has tested interfacial adhesion properties of UV resin/glass substrate interfaces by 4 point bending test. The interfacial adhesion energies by bare, 30, 60 and 90 sec surface treatments are 0.62, 1.4, 1.36 and 2 $J/m^2$, respectively. The test results showed quantitative comparisons of interfacial fracture energy (G) effect of glass wafer surface roughness.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.91-94
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• 2009

We propose advanced liquid crystal display (LCD) modes through surface modification using UV curable reactive mesogen (RM) mixed with alignment layers. The LC directors on the modified alignment layer are controlled and memorized by the polymerized RMs under an applied voltage. Using the method proposed here, we can improve the response time and viewing angle characteristics through surface controlled patterned vertical alignment (SC-PVA) mode and 8-domains PVA mode, respectively. Also, we found that the method can be applicable to fabricate multi-domain structures using multiple UV exposure as same as conventional UV alignment method.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.34-35
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• 2000

A Y-branch phase modulator made of an electro-optic(EO) polymer has been designed and fabricated. An EO polymer, PMMA-DR1, is used for the core layer, and UV-curable polymers, UV-15 and UV-15 LV, for the cladding layers. The rib type polymeric waveguides are fabricated by the reactive ion etching method and their EO effects are obtained by the poling process. The optical properties of the fabricated phase modulator are as follows: the halfwave voltage, $V_{\pi}$, is 25 V, the insertion loss of TM mode is 13.8 dB, and the intensity modulation is 0.17 % (V).

• Transactions of Materials Processing
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• v.19 no.2
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• pp.73-78
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• 2010

Recently, many researches on the development of super-hydrophobic surface have been concentrated on the fabrication of nano-patterned products. Nano-patterned mold is a key to replicate nano-patterned products by mass production process such as injection molding and UV molding. The present paper proposes the new fabricating method of nano-patterned mold at low cost. The nano-patterned mold was fabricated by electroforming the anodic aluminum oxide membrane filled with UV curable resin in nano-hole by capillary phenomenon. As a result, the final mold with nano-patterns which have the holes with the diameter of 100~200 nm was fabricated. Furthermore, the UV-molded products with clear nano- patterns which have the pillars with the diameter of 100~200nm were achieved.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.1023-1028
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• 2018

Shape memory materials are widely used in high-tech industries. Although shape memory polymers have been developed, they have a disadvantage, only unidirectional resilience. Shape memory polymers with bi-directional recovery resilience have been actively studied. In this study, a bidirectional shape memory polyurethane was synthesized using poly(${\varepsilon}$-caprolactone) diol, methylene dicyclohexyl diisocyanate, and hydroxyethyl acrylate. The first physical curing occurred between hard segments and hydrogen bondings when the solution was dried. The second curing in acrylate groups was performed by UV exposure. A degree of curing was analyzed by infrared spectroscopy. The shape memory properties of 2 step-cured polyurethanes were investigated as a function of UV curing time.

• Polymer(Korea)
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• v.36 no.3
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• pp.315-320
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• 2012

Ultra violet (UV) curable pressure sensitive adhesives (PSA) were prepared by controlling both the structure of acryl copolymer and the functionality and content of multi-functional monomers. Acryl copolymer worked as the base polymer for giving the tackiness. Multi-functional monomers were used to vary the crosslinked structure and the degree of crosslink. Acryl copolymer showed the reduced peel strength after UV curing by decreasing the content of 2-ethylhexyl acrylate in the monomer composition. Both the peel strength of PSA and the content of residue found on silicon wafer decreased after UV curing by increasing the functionality of multi-functional monomers. UV curable PSA containing 20 phr six-functional monomer showed the higher peel strength before UV curing and the lower peel strength and the least residue on silicon wafer after UV curing.

• Fibers and Polymers
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• v.2 no.3
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• pp.141-147
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• 2001

The effect of compositions of isophorone diisocyanate (IPDl)/4.4'-diphenylmethane diisocyalate (MDI) and polypropylene oxide diol (PPG, $M_w$: 3000)/1,4-butane diol (BD) on the properties of UV-cured polyurethane acrylate films based on 2-hydroxyethyl acrylate (HEA) was examined. UV-curable polyurethane acrylates were formulated from the prepolymer. trimethylol propane triacrylate (TMPTA) as a reactive diluent, and 1-hydroxycyclohexyl ketone (Irgacure 184) as a photoinitiator. Dynamic mechanical thermal properties and elastic properties of UV-cured polyurethane acrylates was fecund to depend on the chemical composition of IPDl/MDl and PPG/BD. As the BD content increased, the tensile storage modulus of all series samples increased significantly. The storage modulus increased in the order of samples A (IPDI based samples)> samples B (IPDI/MDl (7/3 molar ratio) based samples) > samples C (IPDI/MDl (5/5 molar ratio) based samples at the same composition. Two distinct louts modulus peaks for all samples are observed owing to the softs segment glass transition temperature ($T_gh$) and hard segment glass transition temperature ($T_gh$). The difference between $T_gh$, and $T_gh$, (Δ$T_g$) increases in the order of A > B > C at the same composition. In cycle test, the initial onset strain (%) was found to decrease with increasing BD content in PPG/BD and with increasing MDI content in IPDI/MDl.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.875-880
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• 2016

In this study, we proposed an effective and simple way to directly generate wrinkle patterns on a curved surface. A curved surface was prepared using a 3D printer and an UV (Ultraviolet)-lighting system was utilized to weakly polymerize the UV-curable thin resin layer coated on the surface, resulting in a gradient of material properties in the layer thickness. Subsequently, a thermal curing process was conducted to generate microscale wrinkles by compressive forces that were generated during complete curing. Wrinkle shapes from 5, 15, 25 sec of UV-light exposure were compared. With increasing UV-exposure, the line-width of wrinkles became thicker due to much higher strength of skin zone. The results indicated that the proposed fabrication process could be utilized for surface modification in diverse research fields.