• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.516-519
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• 2003

We modified the molecular structure of urethane acrylate oligomer by varying raw materials. Also fluorination of the host polymer matrices has been found to influence the morphological and the electrooptical properties of the resulting HPDLC grating. The incorporation of fluorinated monomers in HPDLC formulation enhance the LC phase separation and improved elctro-optical properties.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.82-83
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• 2001

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.218-218
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• 2006

A number of new ideas have been implemented to control the droplet morphology and electrooptic properties of holographic polymer dispersed liquid crystal (HPDLC). Doping of conductive fullerene particles to the conventional HPDLC induced dual effects of reducing both droplet coalescence and operating voltage. Chain transfer agent gave higher gel content with lower crosslink density, less dark reactions and less grating shrinkage with much smooth LC-polymer interfaces. Addition of octanoic acid (OA) to the formulation of HPDLC gave a decrease in droplet size and monotonic increase of the off state diffraction throughout the OA content.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.494-499
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• 1999

We report on the results of holographic transmission grating that can be controlled by the applied AC electric field. We have fabricated a polymer-dispersed liquid crystal material that composed of multifunctional acrylate monomer blended with the liquid crystal mixture E7. To investigate an electro-optic properties of fabricated HPDLC, diffraction efficienties (DE) are measured as a fuction of applied electric field and density of liquid crystal. Maximum DE of about 70% is obtained about 30 wt% of LC concentration at a zero field. We have also shown that optical image was recorded in the tllm, and then the reconstructive image was switchable with the applied electric fields. ields.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.91-95
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• 2001

Reflective holographic polymer dispersed liquid crystal(HPDLC) device has a multilayer structure consisting of alternate layers of polymer and liquid crystal droplets. Periodic modulation of a refractive index reflects light of a specific wavelength in accordance with Braggs law. Samples cured isotropically were illuminated with an Argon-ion lase at 514nm. We optimized the reflcetion efficiency of HPDLC as a function of monomer functionality, LC composition and irradiation intensity. The properties of the HPDLC films were observed by UV-visible spectroscopy. We found that the maximum reflection efficiency depends on the monomer functionality, LC composition, and laser intensity. We expect these films could be used in full-color reflective display by stacking them to obtain a mixture of colors.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1212-1215
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• 2004

Diffraction modes of holographic grating were fabricated with polyurethane acrylates(PUA). Two types of silica (AEROSIL 200 and AEROSIL R812) were added to reduce the shrinkage of polymer matrix. It was founded that shrinkage of PUA composite film was reduced with the addition of silica. HPDLC based PUA/silica composite also showed high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1208-1211
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• 2004

When irradiated with visible light in HPDLC, photoinitiator and coinitiator produce a radical for photopolymerization. According to the kinds of photoinitiator and coinitiator, quantity and rate of produced a radical is different. It is influence on photopolymerization rate relate on diffraction efficiency. Thus, this paper is about the effect of photoinitiator/coinitiator combinations in terms of diffraction efficiency and real-time first order diffraction efficiency.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.154-155
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• 1999

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1216-1219
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• 2004

LC and polymer miscibility in HPDLC has been studied in terms of solubility parameter. It was found that better grating formation and diffraction efficiency were obtained when the difference in solubility parameters between polymer and LC is greater.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.520-523
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• 2003

We used three types of reactive diluents with different chemical structures, N-vinyl-pyrrollidone(NVP), ethyl hexyl acrylate(EHA) and hydroxyehtyl methacrylate(HEMA). It was founded that N-vinylpyrrollidone(NVP) and ethyl hexyl acrylate(EHA) based PUA with low molecular weight polypropylene glycol(PPG) at low oligomer content give high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).