1999 Fiscal Year Final Research Report Summary
Liquid Crystal Alignment Induced by Polyimides Exposed to Linearly Polarized Light
| Project/Area Number |
10555301
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
工業物理化学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IKEDA Tomiki Tokyo Institute of Technology, Research laboratory of Resources Utilization, Professor, 資源化学研究所, 教授 (40143656)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEUCHI Yasumasa JSR Corporation, Senior Technical Advisor, 担当役員付常勤顧問、研究職
KANAZAWA Akihiko Tokyo Institute of Technology, Research laboratory of Resources Utilization, Assistant Professor, 資源化学研究所, 助手 (80272714)
SHIONO Takeshi Tokyo Institute of Technology, Research laboratory of Resources Utilization, Associate Professor, 資源化学研究所, 助教授 (10170846)
MATSUKI Yasuo JSR Corporation, Fine Electronic Research Laboratories, Senior Research Scientist, 精密電子研究所, テーマリーダー研究職
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| Project Period (FY) |
1998 – 1999
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| Keywords | Polyimide / Alignment Layer / Polarized Light / Liquid Crystals / Photoinduced Alignment / Non-Rubbing Alignment / 光駆動 |
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| Research Abstract |
Through this study on photoalignment (non-robbing alignment) technique for liquid crystal (LC) devices, we have revealed that aromatic polyimides (Pis) exposed to linearly polarized UV light (366 nm) show a high alignment efficiency without significant change in the chemical structure of PIs. We extended the PI films as an alignment layer to dynamic control technique of nematic LCs (NICs). The most significant characteristic of this system is to utilize photoinduced Freedericksz transition as a trigger to control alignment of NICs. We realized the optical switching of with the photosensitive PIs containing benzophenone moiety as an alignment film. It became clear that the threshold voltage of Freedericksz transition, at which change in the LC alignment occurs, is quite different between irradiated and unitradiated conditions. It was found that photoirradiation at 366 nm resulted in the immediate change in the transmittance when bias voltage of 4.5 V was applied across the cell. Although the mechanism is not well understood at the present stage, formation of intra- or intermolecular charge transfer complexes in the surface area of PI films by photoirradiation ( i.e., change in the polarity) seems to participate in the phenomenon. In conclusion, we have shown for the first time that the photosensitive PI films enable optical control of Freedericksz transition of NLCs. This phenomenon is useful for development of polarization-controllable materials in which permanent electric polarization is controlled by change in dipolar alignment based on Freedericksz transition.
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