Ferroeloctricity in cholesteric liquid crystals of polypeptide and its helicoidal cavity effect of SHG

多肽胆甾液晶的铁电性及其二次谐波螺旋腔效应

• 批准号: 10450361
• 负责人: WATANABE Junji
• 金额: $ 8.13万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450361/
• 关键词: polypeptide; cholesteric liquid crystal; helical structure; second harmonic generation; ferroelectricity; helicoidal cavity effect; dipole moment; polar structure; らせん分布型キャビティー効果; 強誘電液晶

Relatively strong second harmonic generation (SHG) was observed in the lyotropic cholesteric phase of the poly(γ-benzyl L-glutamate) (PBLG) in benzyl alcohol (BA) with application of an electric field. Using an SHG interferometry technique, we confirmed that the phase of SHG was reversed by reversing the electric field, clearly indicating the switching of nonlinear polarization. By applying a triangular wave voltage, a switching current peak was observed, indicating the existence of spontaneous polarization.SHG was also observed in a cholesteric solid film of PBLG using fundamental light propagating along the helicoidal axis. Relatively strong SH light was observed when the optical pitch in the helicoid was the same as the SH-light wavelength, although, otherwise, the generated SH light was canceled by the helicoid so that the SH intensity was negligibly weak.Based on these experimental results, we safely concluded that the cholesteric phase of the PBLGBA lyotropic system is in fact a ferroelectric cholesteric phase, where a polar plane rotates along the helical axis. This is the first proper ferroelectricity in liquid crystals.

在施加电场的情况下，在苯甲醇（BA）中的聚（γ-L-谷氨酸苄酯）（PBLG）的溶致胆甾相中观察到相对较强的二次谐波产生（SHG）。使用二次谐波干涉技术，我们证实了二次谐波的相位通过反转电场而反转，清楚地表明了非线性偏振的切换。通过施加三角波电压，观察到开关电流峰值，表明自发极化的存在。利用沿螺旋轴传播的基波光，在PBLG的胆甾型固体薄膜中观察到了SHG。当螺旋体中的光节距与SH光波长相同时，观察到相对较强的SH光，尽管否则，产生的SH光被螺旋体抵消，因此SH强度微弱到可以忽略不计。基于这些实验结果，我们有把握地得出结论，PBLGBA溶致体系的胆甾相实际上是铁电胆甾相，其中极面沿着螺旋旋转 轴。这是液晶中第一个固有的铁电性。

项目成果

H. Hakezoe and J. Watanabe: "Ferroelectricity in Liquid Crystals"Mol. Cryst. Liq. Cryst.. 328. 325-372 (1999)

H. Hakezoe 和 J. Watanabe：“液晶中的铁电性”Mol。

J. Watanabe, et. al.: "Polar structure in polypeptide cholesteric liquid crystals evidenced from SHG due to the helicoidal cavity effect"Macromolecules. 31, (19). 5937-5939 (1998)

J.渡边等。

J. Watanabe, et. al.: "Ferroelectricity of lyotropic liquid crystal of poly L-glutamate"Jpn. J. Appl. Phys.. 37. L136-L138 (1998)

J.渡边等。

J.Watanabe 他4名: "Enhancement of second harmonic generation due to the selective reflection of cholesteric liquid crystals"Mol.Cryst.Liq.Cryst.. (in press).

J. Watanabe 和其他 4 人：“由于胆甾型液晶的选择性反射而增强二次谐波的产生”Mol.Cryst.Liq.Cryst..（出版中）。

J.Watanabe 他2名: "Molecular Modeling of Polar Rod Like Molecules"Mol.Cryst.Liq.Cryst.. (in press).

J. Watanabe 和另外 2 人：“极棒状分子的分子建模”Mol.Cryst.Liq.Cryst..（正在出版）。