• Bulletin of the Korean Chemical Society
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• 제22권3호
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• pp.271-275
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• 2001

We investigated H-type molecular aggregation in a simply spin-coated amorphous homopolymer film of polymethacrylate containing push-pull azobenzene moieties. It was found that the aggregate formation was strongly influenced by thermal treatment an d that the aggregate created in the polymer film could be easily disrupted by irradiation of a linearly polarized light. In the first writing cycle of aggregated polymer film, photo-induced birefringence showed a steep increase to the highest value followed by a gradual decrease to the certain asymptotic value under longer irradiation of a linearly polarized light. This unique behavior could be attributed to the cooperative motion and the disruption of the aggregated molecules under continuous irradiation of light.

• 한국정밀공학회지
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• 제29권5호
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• pp.572-577
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• 2012

Recently porous polymer has widely been applied to packaging, heat isolation, and sound absorption in various fields from the electrics to the automobiles industry. A lot of micro porosities inside foamed polymer provide lower heat conduction and lighter weight than non-porous polymer, because they involve gas or air during foaming process. In this paper experimental approaches of the UV laser micro machining behavior for Expanded Polypropylene (EPP) foamed polymer materials, which have different expansion rates, were investigated. From these results, the ablation phenomena were finally observed that the ablation is depended upon stronger photo-chemical than photo-thermal effect. This study will also help us to understand interaction between UV laser beam and porous polymer.

• 폴리머
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• 제31권5호
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• pp.442-446
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• 2007

알칼리 가용성, 광경화형 폴리에스터를 합성하기 위해 플루오렌형 에폭시 아크릴레이트에 다양한 산 2 무 수물을 반응시켰다. LCD (liquid crystal display) 컬러 필터용 블랙매트릭스를 제조하기 위해서 합성된 폴리에스터와 카본블랙 등을 혼합하여 포토레지스트 용액을 조제한 후 리소그래피 공정을 통해 유리 기판 위에 블랙매트릭스패턴을 형성하였다. 합성된 다양한 폴리에스터의 특성과 리소그래피 패턴을 비교 조사하였다.

• Journal of Information Display
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• 제8권1호
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• pp.6-9
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• 2007

Orientational alignment patterns have been proven to be that they are very useful for realizing diverse properties of liquid crystals. Here we produced the patterns combining interfered laser beams. A photo-isomerizable polymer including azo unit, which induces nematic liquid crystal alignment to the polarized laser light, was used as the alignment to layer. Double irradiations into two orthogonal directions brought the orientation patterns similar to the checkerboard. It indicates the possibility of bistability on those patterns.

• Macromolecular Research
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• 제17권11호
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• pp.926-930
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• 2009

A new method for encapsulating nanomaterials within intermediary layer cross-linked (ILCL) polymeric micelles using a bifunctional photo-cross-linking agent was developed. For ILCL polymeric micelles, an amphiphilic triblock copolymer of poly(ethylene glycol)-b-poly(2-hydroxyethyl methacrylate)-b-poly(methyl methacrylate) (PEG-PHEMA-PMMA) was synthesized via consecutive atom transfer radical polymerization (ATRP), Di(4-hydroxyl benzophenone) dodecanedioate (BPD) was used as a bifunctional photo-cross-linking agent. The PMMA-tethered Au nanoparticles and BPD, or pyrene and BPD were encapsulated in the PEG-PHEMA-PMMA micelles, and their intermediary layers were photo-cross-linked by UV irradiation for 1 h. The HEMA units donated labile hydrogens to the excited-state benzophenone groups in BPD, and they were subsequently cross-linked by BPD through radical-radical combination. The spherical structures of the PEG-PHEMA-PMMA micelles containing the Au nanoparticles or pyrene were unaffected by the photo-cross-linking process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.181-184
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• 2000

A new photo-alignment material, copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy) chalcone-chalconemethacryl) was synthesized and the electro-optical (EO) characteristics for the photo-aligned vertically aligned (VA)-LC display (LCD) were investigated. The monodomain alignment of the NLC for the photo-aligned VA-LCD by linearly polarized UV exposure on the photo-dimerized copoly (PM4Ch-ChMA) surfaces was observed. Excellent voltage-transmittance characteristics for the photo-aligned VA-LCD by UV exposure for 1 min. on the copoly (PM4Ch-ChMA) surfaces were achieved. The response time of the photo-aligned VA-LCD by UV exposure on for 1 min. the copoly (PM4Ch-ChMA) surfaces was about 39.3 ms. The response time for the photo-aligned VA-LCD decreased with increasing UV exposure time.

• Transactions on Electrical and Electronic Materials
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• 제1권3호
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• pp.10-13
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• 2000

In this study the new photo-alignment material copoly(PM4Ch-ChMa)(copoly (poly (4-methancryloyloxy)chalcone-cholesteryl methacry late)) was synthesized, Also, the liquid crystal (LC) aligning capabilities and the electro-optical(EO) characteristics for the photo-aligned vertical-aligned(VA)-LC display(LCD) were studied. The monodomain alignment of the NLC for the photo-aligned VA-LCD by linearly polarized UB exposure on the Photo-dimerized copoly(PM4Ch-ChMA) surface was observed,. Excellent Voltage-transmittance characteristics for the VA-LCD photo-aligned by polarized UV exposure on the copoly (PM4Ch-ChMA) surfaces for 1 min was achieved. The response time of the VA-LCD photo-aligned by polarized UV exposure on the copoly (PM4Ch-ChMA) surfaces for 1 min was 39.3 ms, We suggest that the photo-dimerized chacone group increased with increasing UV exposure time, which then contributes to a low response time of the photo-aligned VA-LCD on the copoly (PM4Ch-ChMA) surfaces.

• 한국정밀공학회지
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• 제24권1호
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• pp.71-78
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• 2007

Abrasive jet machining (AJM) has been traditionally used for removing rusts or paints. Nowadays, this is promising technology for micro bulk machining where brittle substrate materials are used. In order to get accurate details, masks such as metal, polymer or elastomer is inevitable. Among them, photo polymer which is sensitive to the light has been attractive for it's high accuracy using photolithography. In this research, SU-8 as a photo polymer is used since it is adequate for making thick mask. So, this paper describes how to make AJM masks using SU-8 with a photolithography process, and investigates the characteristics of SU-8 masks during AJM process. Also, an example of fabrication using AJM was shown.

• 한국응용과학기술학회지
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• 제17권3호
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• pp.192-197
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• 2000

Rosin moeity-containing monomer was prepared by the reaction of abietic acid with 2-hydroxyethyl methacrylate in tetrahydrofuran(THF) using diethyl azodicarboxylate as a catalyst. This new monomer was photo-polymerized to give thin films in the presence of a radical type initiator. The rate of photo-polymerization and amount of cured polymer were determined using the residual yield method. A thermogravimetric analysis of the cured polymer showed that the film was stable up to 170oC, at which point the polymer film has lost 10 wt % of its weight.

• Macromolecular Research
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• 제15권6호
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• pp.560-564
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• 2007

The photostabilization and cure kinetics of UV-curable, optical resins containing various formulations of photostabilizers were investigated to determine the system with the highest cure conversion and durability. Photo-DSC analysis revealed that increasing the concentration of a UV absorber (UVA) decreased both the crosslink density and the cure rate due to competition for the incident photons between the photoinitiator and the UVA, whereas including a hindered amine light stabilizer (HALS) hardly affected either the cure conversion or the cure rate due to its very low absorption of 365 nm. This result was confirmed by FTIR-ATR spectroscopy and UV-visible spectroscopy analyses. QUV ageing experiments showed that the cure conversion and durability were the highest for the UVA/HALS formulation at a ratio of 1 : 2, which is due to their synergistic action.