Molecular Theoretical Studies on Surface Tension and Molecular Orientation in Liquid Crystals
| Project/Area Number |
61550012
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | Nagoya University |
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Principal Investigator |
HATSUO KIMURA School of Engineering,Nagoya University,Professor, 工学部, 教授 (60023032)
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| Co-Investigator(Kenkyū-buntansha) |
羽賀 栄次郎 名古屋大学, 工学部, 教授 (40023006)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | Surface tension / Molecular orientation at interface / Molecular theory of liquid crystals / Intermolecular forces / Nematic-isotropic interface / スメクチック液晶 / ネマチック一等方相界面 / 平滑面固体基板壁 / 界面での分子配向 / 分子間引力ポテンシャル / 分子間排除体積効果 / 垂直から斜めへの相転移 / 平行から垂直への相転移 / スメクティック相の分子論的機構 / 液晶の表面張力 / 液晶界面での分子配向 / 液晶の分子論 / 排除体積効果 |
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| Research Abstract |
The surface tensions of the nematic liquid crystal are calculated molecular theoratically in mean field approximation at (a)the free surface, (b)the nematic-isotropic (N-I) interface, and (c)the wall of a hard flat material. The liquid crystal is assumed to be the system of hard rod-like molecules.The results express the surface tensions as functions of the nematic director and the molecular orientational order parameter,and each expression consists of respective contributions from (1) the attractive intermolecular force and (2) the excluded volume effect due to the hard core repulsions. It is found that the excluded volume effect favours the normal alignment of molecules at the free surface, While it favours the planar orientation at the N-I interface and on the hard flat wall.
On the other hand,the attractive force,depending on the coupling constants for each molecule,favours one of the normal,tilted and planar orientations irrespective of the kind of interface. On the basis of the theory, many experiments such as the followings are analysed and consistently explained as interplay of the repulsive and attractive forces. (1) Many kind of nematic molecules orient normally at the free surface and planarly on hard walls, (2) the orientation of MBBA and EBBA molecules at the free surface changes continuously from normal to tilted wten the temperature is decreased, (3) the molecular orientation of 70CB and of mixtures of 8CD and 80CB on hard flat wall changes from planar to normal likely as the first order phase transition with the decrease of temperature.
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Report
(4 results)
Research Products
(26 results)
