High Speed Optical switching and Long Memory Life for (Liquid Crystalline Polymer/Liquid Crystal) Compopsite Films

(1)本文研究了侧链上带有弱极性甲氧基端基的侧链嵌段液晶聚合物（嵌段LCP）及其共聚物与每个侧链上带有强极性氰基端基的低分子量嵌段液晶（嵌段LC）复合的诱导近晶复合体系的可逆电光开关特性和非可逆电光开关特性。在侧链中引入弱极性甲氧基端基的液晶共聚物（LCcoP），可以提高二元复合体系在室温下的光开关和可逆光开关的响应速度。由于具有52.5mol%取代的介晶侧链的LCcoP没有表现出中间相特征，因此在本研究中将该LCcoP命名为伪LCcoP。（pseudo LCcoP/PEN-LCs）复合体系在很宽的混合浓度和温度范围内显示出诱导的近晶相。一种响应时间短的可逆电光开关（ ...更多信息 在室温下施加适当的电场，诱导近晶二元复合体系的相变时间可达100 ms。此外，该二元复合系统显示出可逆的和基于介电各向异性的符号反转的电光开关时，与高（10 kHz）和更高（100 kHz）的驱动频率的交流电场的应用。(2)为了改善侧链液晶共聚物（LCcoP）在两种不同频率电场驱动下的可逆电光开关特性，研究了侧链液晶共聚物（LCcoP）中的介晶侧链含量对近晶态（LCcoP/低分子量双相液晶：LCcoLCs）复合体系电光效应的影响.当LCcoP含量低于40wt%时，复合体系的玻璃化转变温度（Tg）和中间相温度范围与LCcoP中的介晶侧链含量无关，分别为约220 K和220- 340 K。在LCcoP分数为30wt%以及其介晶侧链分数为52.5和32.5摩尔%的情况下，二元复合体系在室温下显示出均匀的近晶相。另一方面，具有16.5摩尔%的介晶链侧分数的LCcoP在没有任何LC添加的情况下在任何温度下都不表现出任何介晶特征。因此，在本研究中将这种LCcoP命名为伪LCcoP。然而，（pseudo LCcoP/PEN-LCs）复合体系在混合浓度（35- 85wt%的pseudo LCcoP）和温度（220- 320 K）的宽范围内显示出新型的诱导近晶相。该复合体系具有从透明态到光散射态的快速转变。因此，可以合理地得出结论，具有介晶侧链的最佳取代基分数的LCcoP的应用对于在室温下实现高的电光开关速度（~ 50 ms）以及稳定的记忆效应（~ 100年）是有用的。少

(1) Reversible and bistable electro-optical switching characteristics of induced smectic composite systems compound of a side chain nematic liquid crystalline polymer (nematic LCP) and its copolymer with weak polar methoxy terminal groups in the side chains and low molecular weight nematic liquid crystals (nematic LCs) with each strong polar cyano end have been investigated. The liquid crystalline copolymer (LCcoP) with weak polar methoxy terminal groups in the side chains was used to improve the response speed at room temperature for the bistable and reversible light switching of the binary composite system. Since LCcoP with 52.5 mol% substituted mesogenic side chains did not exhibit mesophase characteristics, this LCcoP was named as pseudo LCcoP in the present study. The (pseudo LCcoP/nematic LCs) composite system showed an induced smectic phase over a wide range of mixing concentration and temperatures. A reversible and bistable electro-optical switching with a short response time ( … More 〜100 ms) was realized for the induced smectic binary composite system upon the application of an appropriate electric field at room temperature. Also, the binary composite system showed a reversible and bistable electro-optical switching based on the sign reversal of the dielectric anisotropy upon the application of ac electric fields with high (〜kHz) and higher (〜100kHz) driving frequencies.(2) The influence of the mesogenic side chain fraction in side chain liquid crystalline copolymer (LCcoP) on electro-optical effects for (LCcoP/low molecular weight nematic liquid crystals : nematic LCs) composite system in a smectic state was studied in order to improve reversible and bistable electro-optical switching characteristics driven by as electro fields with two different frequencies. In the case of LCcoP fraction lower than 40wt% the magnitudes of glass transition temperature (Tg) and the mesophase temperature range for the binary composite systems were independent of the mesogenic side chain fraction in LCcoP, that is 〜220 K and 220-340K, respectively. In the case of the LCcoP fraction of 30wt% and also, its mesogenic side chain fraction of 52.5 and 32.5 mol%, the binary composite systems showed a homogeneous smectic phase at room temperature. On the other hand, the LCcoP with mesogenic chain side fraction of 16.5 mol% did not exhibit any mesomorphic characteristics at any temperature without any addition of LCs. Then, this LCcoP was named as the pseudo LCcoP in this study. However, the (pseudo LCcoP/nematic LCs) composite system showed a novel type of induced smectic phase over a wide range of both mixing concentration (35-85 wt% of the pseudo LCcoP) and temperature (220-320K). This composite system showed a fast switching speed form a transparency state to a light scattering state. Therefore, it was reasonably concluded that the application of LCcoP with the optimum substituent fraction of mesogenic side chain is useful to realize a high electro-optical switching speed (〜50 ms) as well as a stable memory effect (〜years) at room temperatures. Less