Liquid Crystal Polymer Systems For Rewritable Optical Recording

研究了两种光敏液晶系统在可逆光记忆中的应用。(1)在紫外光照射下，掺杂偶氮苯的向列相液晶聚合物的光致相转变为各向同性相，通过在侧链上附着非介生残基，介相的序参量降低，使其光致相转变为各向同性相。向列相的恢复是由蓝光照射引起的，尽管需要一段老化期。(1)用线偏振光照射覆盖光致变色分子层的基板制成的电池，控制向列液晶层的方位排列。基于这一工作原理的光存储器的改写是通过改变光化光的电矢量来实现的。(2)开发了三种以上类型的光定向聚合物薄膜。第一个涉及在聚乙烯醇薄膜上表面选择性地引入偶氮发色团。第二种方法是基于在其侧链中以偶氮苯取代的聚合物薄膜的自旋涂覆。第三种方法是在基板上沉积含有偶氮苯单元的聚酰亚胺的Langmuir-Blodgett薄膜。(3)研究了影响图像光学质量的因素和液晶重定向所需的曝光能量。当温度低于向列/各向同性转变温度（T_<N1>）时，能分辨少量母线和空间的照片相当稳定，在T_<N1>以上加热或用不同偏振平面的偏振光覆盖即可擦除。(4)表面介导的光记录技术具有很高的实际意义，因为它可以在单一光源的可见光照射下进行，而偶氮苯没有明显的光降解。少

Two types of photosensitive liquid crystalline systems were studied to apply to reversible opticak memory.1.Photoinduced phase change of liquid crystal polymers(1) Photoinduced phase change of nematic liquid crystalline polymers into isotropic phase under UV-irradiation for the photoisomerization of doped azobenzenes was considerably enhanced by attaching non-mesogenic residues in the side chains as a result of the reduction of an order parameter of the mesophase. The recovery of the nematic phase was caused by illumination with blue light although an aging period was required.2.Liquid crystal alignment photoregulation mediated by polymer surfaces(1) An azimuthal alignment of nematic liquid crystal layrs was controlled by irradiation of a cell fabricated with substrate plates covered with photochromic molecular layrs with linearly polarized light. Rewriting of an optical memory based on this working principle was realized simply by changing an electric vector of actinic light.(2) Three … More types of photoaligning polymer thin films were developed. The first involves the surface-selective introduction of azo-chromophores on a poly (vinyl alcohol) thin film. The second method is based on spin-coating of a thin film of polymers substituted with azobenzenes in their side chains. The third one consists of the deposition of Langmuir-Blodgett films of a polyimide bearing azobenzene units on a substrate plate.(3) Factors affecting optical quality of photoimages and exposure energy required for liquid crystal reorientation were investigated. Photoimages resolving few mum lines and spaces were quite stable at a temperature below a nematic/isotropic transition temperature (T_<N1>) and erased by heating above T_<N1> or simply by overwriting with polarized actinic light with a different polarization plane.(4) The surface-mediated optical recording is highly of practical significances because they can be operated by irradiation with a single light source emitting visible light which results in no observable photodegradation of azobenzenes. Less