聚合物分散液晶光栅的衍射特性的研究

报道了一种由聚合物分散液晶膜与具有周期性条状电极结构板结合的新型光栅器件，借助于聚合物分散液晶膜的电光特性，这种栅对入射光的散射或衍射取决于对其施加的电压，即它是电场可调的，实验结果显示出当驱动电压超过器件器件阈值电压时，衍射光的强度和衍射斑的可见级次被电场调制，而且它能入射光的线性偏振态变为椭圆偏振态。     

聚合物 分散液晶体系的相分离结构对温度依赖性的研究

在不同温度下采用紫外光引发相分离法制备了聚合物分散液晶样品．用光学显微镜及扫描电镜研究了样品的相分离结构．采用对样品施加电压观察其微结构轮廓，或测量液晶微粒相变点的简单方法研究了聚合温度对相分离结果的影响．结果表明，在一定温度范围内，随着温度的增高，液晶微粒的平均尺寸趋于减小，而且形成的液晶微粒也逐渐变纯．作者给出了这些测试结果并进行了讨论．     

芳香共聚酯B-N多种向列织构的形态研究

从一种聚芳酯B-N得到了丝状(包括细丝和粗丝)、纹影状和大理石纹状等与小分子向列液晶相似的多种织构。由于样品淬火后晶片装饰在织构上而不影响分子取向矢的分布,因而可以用化学刻蚀和电镜技术揭示其向错和取向矢图。电镜和光学显微镜的结果相互补充,表明了细丝和粗丝状织构的分子取向矢分布很不相同,是两种不同的织构,而粗化始于第二熔融降温。在这些向列织构中分别发现了S=±(1/2)和s=+1的向错的例子和平面内微区转向壁的证据。     

Molecular field theory for nematic liquid crystal film with finite layers

The nematic liquid crystal film composed of n molecular layers is studied based upon a spatially anisotropic pair potential, which reproduces approximately the elastic free energy density. On condition that the system has perfect nematic order, as in the Lebwohl—Lasher model, the director in the film is isotropic. The effect of the temperature is investigated by means of molecular field theory. Some new results are obtained. Firstly, symmetry breaking takes place when taking account of the temperature, and the state with the director along the normal of the film has the lowest free energy. Secondly, the N—I phase transition temperature increases as an effect of finite sizes instead of decreasing as in the Lebwohl—Lasher model. Thirdly, the nematic order is induced in the layers near the surface in the isotropic phase.     

Exploration of the sum of flexoelectric coef ficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry,which comprises pyramid,matching fluid,and strongly anchored hybrid aligned nematic liquid crystal(NLC) cell on the internal angle.The calculation is based on the multi layer optical theory and the elastic theory of liquid crystals.For different sums of flexoelectric coefficients e11 and e33,the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients.Consequently,the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.     

侧链胆甾液晶聚合物及弹性体的液晶性能研究

把胆甾液晶单体 4 烯丙氧基苯甲酸胆甾醇酯 (Mch)分别和向列液晶单体 4 烯丙氧基苯甲酰氧基 4′ 甲氧基苯 (Mn) ,向列液晶交联剂 2 叔丁基对苯二酚双 [4 (6 丙烯酰氧基己氧基 )苯甲酸酯 ](Mnc)接枝到聚硅氧烷链上 ,得到系列侧链液晶聚合物Pn 系列和液晶弹性体Pe 系列 .通过热分析、偏光显微分析和X 射线分析等手段分别研究了向列液晶单体和向列液晶交联剂对含同一胆甾液晶基元聚合物的影响 .结果表明 ,向列液晶单体的摩尔百分比在 80 %以下 ,液晶聚合物Pn 系列为胆甾型液晶 ,在研究的范围内 ,液晶弹性体Pe 系列也为胆甾型液晶 ,Pn 系列和Pe 系列都具有较宽的液晶相范围 ,热分解温度均在 2 80℃以上 .     

液晶散射法产生部分相干光实验

 对无阶梯诱导空间非相干技术中前级光源太弱的问题进行了分析,开展了前级部分相干源的研究工作。利用向列液晶的电光特性,选用两种液晶盒作为散射体,完成了液晶散射法产生部分相干源的原理性实验,得出液晶散射光能量透过率、均匀性及相干性与外加电场的关系。实验表明通过改变外加电场,可以提高液晶散射光的强度和均匀性,同时降低其空间相干性。     

Magneto-optical effect of TEB30A liquid crystal doped with thulium oxides

The influences of an external magnetic field on the optical properties of the TEB30A nematic liquid crystal doped with thulium oxides （Gd203, Dy203, Nd203, Y203, and Sm203） are studied. It is shown that a magnetic field applied parallelly to the sample cell surface leads to the rotational orientation of mesogenes. All samples except for the sample doped with Sm203 nanoparticles undergo structural deformations. The behavior of the TEB30A/Sm203 differs from those of the TEB30A liquid crystal doped with other four nanoparticles. The presence of Sm203 nanoparticles in the TEB30A liquid crystal does not cause the structural deformation of the liquid crystal matrix. At the same time, the anchoring type of the liquid crystal molecules on the nanoparticle surface is different. The director n is parallel to the magnetic moment/~ in the TEB30A/Sm203, and inclined to the magnetic moment/~ in the TEB30A/Nd203, and perpendicular to the magnetic moment/~ in each of TEB30A/Gd203, TEB30A/Dy203, and TEB30A/Y203. Besides, the dependence of the structural deformation on the critical magnetic field for the TEB30A is obtained.