Study on Molecular Orientation Effects in Polymer-Liquid Crystal Composite Systems

聚合物-液晶复合材料简称PDLC（聚合物分散液晶）是用各种可紫外光固化的甲基丙烯酸酯预聚物和具有正或负介电各向异性的向列相液晶制备而成的。PDLC电池可以通过电从光散射关闭状态切换到高度透明的打开状态。在具有相反形态的PDLC细胞中观察到记忆效应，即在去除电压后长时间保持透明度。在电场或磁场的作用下，由各向同性相变到向列相可以很容易地产生记忆态。研究了它们的电光和热光学性质。通过扫描电镜对聚乳酸膜的形貌进行了研究，并对聚合和相分离条件对聚乳酸膜形貌和电光性能的影响进行了测量和讨论。在不同的紫外照射条件下制备了PDLC电池，并在进行相分离的同时测量了透射率、电容和电阻。通过对电阻变化的监测，明确了紫外辐照时间与光电性能之间的关系，确定了最佳的制备条件。本文演示了一种新型光学器件，该器件使用正极型和负极型PDLC电池，仅在关闭状态下向电池法线倾斜的方向传输入射光。在较低的驱动电压下获得了高度透明的存储状态。利用激光束对PDLC单元进行了正、负模式的热寻址和局部擦除。热敏打印机头也成功地将热图像写入柔性PDLC薄膜上。讨论并论证了聚合物-液晶复合材料应用于新型热寻址显示器件的可能性。少

Polymer-liquid crystal composite materials abbreviated by PDLC (polymer dispersed liquid crystals) are prepared using various kinds of UV-curable methacrylate prepolymer and nematic liquid crystals with a positive or a negative dielectric anisotropy. The PDLC cells can be switched electrically from a light scattering off state to a highly transparent on state. Memory effects, in which a transparency is preserved for a long time after a voltage is removed, are observed in PDLC cells with a reversed morphology. The memory states can easily created by the phase transitions from an isotropic to a nematic phase with application of an electric or a magnetic field. Their electrooptical and thermo-optical properties are studied.Morphologies of PDLC films are studied by scanning electron microscope photographs of their sections, and the dependence of polymerization and phase separation conditions on the morphology and electrooptical properties are measured and discussed. PDLC cells are prepared … More with various terms of UV irradiation, and the transmittance, capacitance and resistance are measured while the phase separation is advanced. The relationship between the term of UV irradiation and the electrooptical property can be clarified and the optimum condition to prepare them can be attained by monitoring the change of the resistance.A new type of optical device which transmits the incident light only in directions oblique to the normal of the cell in an off-state is demonstrated using both the positive-type and negative-type PDLC cells.Ad highly transparent memory-state was obtained with relatively low driving voltage. Thermal addressing and local erasure in the positive and negative modes were performed using a laser beam on the PDLC cell. A thermal image was also succesfully written by a thermall printer head onto a flexibele PDLC film.The possibility of application of the polymer-liquid crystaal composites to the new type of thermally addressed display device is discussed and demonstraated. Less