可写式胆甾相液晶显示和检测图像用算法的研究

研究了可写式胆甾相液晶显示(ChLCD)以及检测图像用的算法.我们可以用任何一个硬尖状物体(如指尖),直接在ChLCD表面上写入图像.通过测量测试盒(12mm×15mm/1×1)像素的电容,能够检测到F-状态和P-状态.但是测量4.1in ChLCD(241μm × 241μm/320 × 320)的电容时,却未能够检测到F-状态和P-状态,这主要是由于寄生电容的影响.最后,为了检测到ChLCD上的图像,研究了高频率测量方法和算法.     

利用动态反射法对手性液晶Bragg反射的分析

利用动态反射法对手性液晶材料的选择性反射特性进行了分析。根据理论分析结果，利用MATLAB程序计算了手性液晶膜层的反射光谱，得到了反射光谱随手性液晶的螺距和折射率变化的关系；利用动态反射法可以较为方便、快速地对手性液晶膜的Bragg反射特性进行数值求解分析，分析和计算结果可以为反射式液晶显示的设计和计算提供理论参考。由于在数值求解中引入了简化条件，因此该计算方法只能应用于△n值较小的情况，当Δn值较大时，应该用其他求解方法来完成计算分析工作。     

Compatibility–structural color property relationship of binary blends of acetylated hydroxypropyl celluloses with different degrees of acetylation

Polymer blends containing liquid crystalline cellulose derivatives potentially enable the fabrication of optical functional materials because of their unique optical properties, that is, structural color and circular dichroism. However, studies on the effect of the compatibility of the components on the optical properties of such blends are scarce, even though component compatibility is a crucial factor for the physical properties of the polymer blends. In this study, we investigated the effect of the component compatibility on the structural color property of binary blends of acetylated hydroxypropyl celluloses (AHPCs) with different degrees of acetylation (DS_Ac). The spectroscopic analyses of the AHPC blends revealed that the structural color of blends with a small DS_Ac gap between AHPC components systematically changed with the blend composition, whereas the color of blends with a large DS_Ac gap was independent of the composition. Compatibility tests via spin–lattice relaxation time measurements using solid-state nuclear magnetic resonance indicated that the different composition dependence of the color was attributed to the compatibility of the components, which varied according to the DS_Ac gap.     

胆甾相液晶场致织构变化的偏光显微镜观测

介绍胆甾相液晶的织构和显示应用，给出胆甾相液晶几种织构的偏光显微镜图像。该图像对认识胆甾相液晶的各种织构，理解胆甾相液晶在双稳态显示器的应用原理具有一定的意义。     

Studies of the bistable mechanism in electro-thermal switching polymer-stabilized cholesteric texture light shutters

Our research studied the bistable mechanism in electro-thermal switching reverse polymer-stabilized cholesteric texture (ET-RPSCT) light shutters. The bistable mechanism in ET-RPSCT is a result of a polymer distortion effect induced by applying a high-voltage pulse. It was found that long-pitch cholesteric liquid crystals will maintain a focal conic texture by a distorted polymer network which exhibits a translucent state. An annealing treatment method was used to recover cholesteric liquid crystals back to the planar texture through alignment layers. We compared the ET-RPSCT cells in different polymer network structures, which were built from different UV curable diacrylate monomers and concentrations, resulting in different anchoring forces and polymer distortion effects. We found that when the polymer network structure is tight and fiber-like, the long-pitch cholesteric liquid crystals are more stable in the focal conic texture because of polymer distortion, and are resistant to switching states. On the other hand, the long-pitch cholesteric liquid crystals recover to the planar texture easily by thermal switching due to a loose and grain-like polymer network structure. Furthermore, the effects of polymer structure on the electro-optical performance of ET-RPSCT were also investigated.     

Spatial and Orientational Templating of Semiconducting Polymers in a Cholesteric Liquid Crystal

A one‐dimensional pattern‐forming state of a cholesteric liquid crystal (CLC) is used as a template for the self‐organization of ordered, spatially orientated, acetylene‐based semiconducting polymers. The polymers are formed by metathesis reaction with all chemical components contained in an ordinary electro‐optic cell. The polymer morphology consists of parallel ～ 1 μm thick bundles, uniformly spaced at ～ 10 μm over the full macroscopic active area of the cell substrates. The polymer templating can be explained by a model that predicts a corrugation in polymer density determined by the spatially periodic profile of the orientational energy density associated with the pattern‐forming CLC state.     

Defects in liquid crystals (II)

Defects in the disordered (uniaxial) liquid crystals, nematic, smecticA and cholesteric, and the use of topological analysis in classifying them, are discussed. While the latter is very successful in classifying defects in nematics, it fails to do so in the case of smecticA and cholesteric liquid crystals because of geometrical constraints. However, topological arguments have been partially successful in predicting some of the defects in cholesterics. The known features of the isotropic (cubic and amorphous) cholesteric blue phases are summarised and the various theoretical models picturing them as defect lattices, are also discussed briefly.     

Synthesis and characterization of side‐chain cholesteric liquid‐crystalline polymers derived from steroid substituents

A series of new cholesteric liquid‐crystalline polysiloxanes derived from steroid substituents were synthesized. The chemical structures of the monomers or polymers obtained were characterized by FTIR, element analyses, ¹H NMR, and ¹³C NMR. Their mesogenic properties and thermal stability were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. Monomers exhibited typical cholesteric focal‐conic or spiral texture. The polymers P ₁? P ₆ showed cholesteric phase and P ₇ displayed smectic phase. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

含柔性长链的二元胆甾相新型液晶的制备及其性能研究

以胆甾醇和长链二元酸为原料，合成了一种柔性长链的新型小分子二元胆甾相液晶，并对其相转变过程进行了深入分析。红外光谱、核磁共振谱、质谱和元素分析证实了其分子结构，差示扫描热分析（DSC）谱图和偏光显微镜（POM）观察图像等一致表明其相转变过程完全符合胆甾相液晶的特征。说明胆甾相液晶分子的刚性大小与胆甾相液晶的形成没有直接关系，胆甾相液晶基元是其形成有序排列的决定因素。