| Project/Area Number |
12450133
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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 | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Osaka Sangyo University |
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Principal Investigator |
SUGIMURA Akihiko Osaka Sangyo University, Faculty of Engineering, Professor, 工学部, 教授 (90145813)
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| Co-Investigator(Kenkyū-buntansha) |
NAITO Hiroyoshi Osaka Prefecture University, Faculty of Engineering, Professor, 工学部, 教授 (90172254)
MATSUMOTO Keiji Osaka Sangyo University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40229547)
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| Project Period (FY) |
2000 – 2002
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| Keywords | liquid crystal / deuterium nuclear magnetic resonance spectroscopy / anchoring energy / director distribution / continuum theory / director dynamics / molecular dynamics / surface phenomena |
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| Research Abstract |
Novel deuterium NMR spectroscopy has also been used to investigate the dynamic director alignment process following the application of removal of an electric field in the nematic liquid crystal subject to orthogonal magnetic and pulsed electric fields. The time dependence of the NMR spectra has been measured for a thin nematic film. The director was found to be rotated from being orthogonal to the magnetic field to being parallel to it when the electric field, whose direction was essentially perpendicular to that of the magnetic field, was switched off. The experimental spectra show that the director is uniformly aligned orthogonal to the magnetic field in the initial state and that the director uniformly oriented parallel to this field in the final state. The intermediate states are observed to correspond to a wide director distribution. In the realignment pathway, the directors can rotate equally probably clockwise or counterclockwise and this degeneracy induces a backflow effect. This can be included within the theory by using an effective value of the rotational viscosity which is less than the true value. The time dependence of the director distribution was simulated using the torque balance equation including a time dependent viscosity torque term with an effective rotational viscosity. For the experimental spectra found during the passage of the director from being orthogonal to being parallel to the magnetic field, however, the spectral lines are observed to be broader than those predicted. The domain walls resulting from the degeneracy in the director realignment could cause the failure of the theory to predict the broad director distribution. Although this particular investigation reveals the lack of a good theoretical analysis for the director distribution, deuterium NMR spectroscopy is clearly providing a very valuable technique with which to investigate the director distribution and dynamics in nematic films both dynamic and static.
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