Date
Place
- Room H (Room Hall 1, 1F)
- P1. Poster Session I
- August 20, 2015 (Thursday)
- 14:00 ~ 15:30
- [P1-93]
- 14:00 ~ 15:30
- Title:In-situ Vertical Alignment of Nematic Liquid Crystals Using Photo-Polymerizable Acrylate Mixtures
- Sudarshan Kundu (Chonbuk Nat'l Univ., Korea), Heung-Shik Park, Jae-Jin Lyu (Samsung Display Co., Ltd., Korea), Aboozar Nasrollahi, and Shin-Woong Kang (Chonbuk Nat'l Univ., Korea)
Abstract: In this report, we present anchoring transition of nematic liquid crystal after polymerizing mixture of twoacrylate monomers initially mixed in the nematic host. One polymerizable monomer, reported as PM1 in thisreport has two acrylate groups in one monomer unit. The other polymerizable monomer reported as PM2 in thisreport has one acrylate group in one monomer unit. Both the monomers are commercially available and have beenbought from Sigma Aldrich. PM1 and PM2 have been mixed at 1: 9 weight ratio in a vial. 1.0 wt% of themonomer mixture has been added to a LC mixture with negative dielectric anisotropy. Cells have been fabricatedusing ITO-coated glass plates and 10 ¥ìm-thick tape spacers. Test cells have been filled with the LC mixture,doped monomer mixtures, at a temperature, a few degrees above TNI. One cell has then been examined underpolarized optical microscope (POM). A random planar texture has been observed at room temperature. The filledcell has been heated to the temperature a few degrees above the nematic-isotropic transition temperature (TNI) andthen exposed to UV-light with the intensity of 200 ¥ìW/cm2 for 1 hour. After irradiation of UV, the cell has beencooled under POM. A quick anchoring transition from random planar to homeotropic state has been observed justa few degrees below the TNI. The cell has been washed in pure hexane to remove the LC mixture and then refilledagain with the same LC in its pristine state. No planar texture has been observed after the refill. Hence it has beenrealized that the surface modification was permanent against solvent treatment and was strongly adhered to theITO surface. The cell has then been un-assembled to study the surface morphology. The surface morphology hasbeen performed by using FE-SEM and AFM. Another cell with optimized cell gap for the host LC has beenfabricated and then has been irradiated under UV at isotropic temperature and similar anchoring transition hasbeen observed. The electro-optic characteristics have been measured of the cell with optimized cell gap. Theexperimental details and results will be presented in the meeting.
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