溶剂的溶胀与乙基氰乙基纤维素胆甾相结构变化

乙基氰乙基纤维素 [(E -CE)C]/聚丙烯酸 [PAA]分子复合物通过用光引发聚合乙基氰乙基纤维素 /丙烯酸胆甾型液晶溶液中的丙烯酸得到。在 (E -CE)C/PAA分子复合物中 ,PAA在水中的溶胀影响到胆甾型液晶相结构。胆甾型液晶相选择性反射光的波长随着PAA的溶胀向长波方向位移。同时还发现 ,在PAA溶胀过程中胆甾型液晶相的螺距增加 ,取向分子层之间的距离减小。     

PDCLC膜光电性能的研究以及柔性液晶盒的制备

用紫外光诱导相分离方法制备了聚合物分散胆甾相液晶（PDCLC）薄膜,研究了固化光强对薄膜形态以及光电性能的影响,同时探讨了不同制备条件下PDCLC膜的相形态变化与光电性能之间的关系。研究表明：固化光强较低时相分离较完全,产生的液晶微滴尺寸较大,相应的光电性能包括反射率、对比度以及响应时间有所改善。采用上述探讨的优化条件,成功地制备了尺寸为7cm2的反射式柔性双稳态液晶盒。     

辊压法制备柔性双稳态液晶显示器件

基于PET塑料薄膜取代硬质玻璃作为基板材料制备柔性液晶盒时,采用传统制备工艺会产生盒厚度不均以及盒中残留气泡等现象,导致柔性液晶器件性能变差。采用辊压工艺可以有效地解决上述问题,文章对其工艺流程进行了详细描述。实验发现,通过在辊压工艺中加热两片基板以降低溶液的黏度,能够有效地避免气泡残留,获得厚度均匀的柔性液晶盒。应用辊压工艺和聚合物分散胆甾相液晶,成功地制备了尺寸为7cm2的反射式柔性双稳态液晶盒。利用正交偏光显微镜观察了聚合物分散液晶的相形态,紫外分光光度计测试了其光电性能:最高反射率为22.8%,对比度为2.259,阈值电压为78V,饱和电压为99V。     

Analysis of Cavity‐Mode Lasing Characteristics from a Resonator with Broadband Cholesteric Liquid‐Crystal Bragg Reflectors

Detailed optical lasing characteristics in liquid crystal (LC) microlasers consisting of multiple polymer cholesteric LC (PCLC) layers are presented as broadband resonators sandwiching a layer of thick gain media, dye‐containing nematic LC (NLC) or isotropic liquid, in between. Multiple lasing emission peaks due to Fabry‐Perot cavity modes are observed for both gain media, and their polarization characteristics investigated. To analyze lasing characteristics, specified eigen modes are defined, the polarization states of which are maintained before and after passing through the broadband resonator, and obtained for the present full system by using the Berreman 4 × 4 matrix method. Using these specified eigen modes, the optical density for each mode is calculated and compared with the experimental results, and shows good agreement. Finally, lasing characteristics between the resonators with NLC and isotropic gain media are compared, and the advantages of adopting dye‐doped NLC gain medium are shown for tunable red, green, blue lasing in a microlaser system with a broadband resonator.     

Nanoscale Organization of a Platinum(II) Acetylide Cholesteric Liquid Crystal Molecular Glass for Photonics Applications

The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans‐Pt(PEt₃)₂(C?C?C₆H₅?C?N)(C?C?C₆H₅?COO?Cholesterol), are described and designated as PE1‐CN‐Chol. Polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray scattering experiments show room temperature glassy/crystalline texture with crystal formation upon heating to 165 °C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1‐CN‐Chol monolayer reveals self‐assembly at the solid?liquid interface with an array of two molecules arranged in pairs, oriented head‐to‐head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials.     

新型胆固醇侧部衍生物的合成研究

对胆固醇的双键进行环氧化,然后分别用4-溴丁酸、5-溴戊酸和6-溴己酸进行开环氧化,将柔性链键接到胆固醇的腰上,再分别与甲基丙烯酸钾进行反应,得到了3个新型的含柔性链腰接胆固醇的甲基丙烯酸酯衍生物单体,从而为合成新型的含胆固醇衍生物的聚合物研究奠定了基础。     

Synthesis,structure, and phase behavior of new chiral liquid‐crystalline polysiloxanes based on mesogenic menthyl monomers

Six new chiral monomers ( M ₁ – M ₆ ), and their corresponding side chain polymers ( P ₁ – P ₆ ) containing menthyl groups were synthesized. The chemical structures of M ₁ – M ₆ were characterized with FTIR and ¹H NMR. The structure–property relationships of the monomers and polymers obtained are discussed. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. Some compounds containing menthyl groups formed mesophase when a flexible spacer was inserted between the mesogenic core and the menthyl groups by reducing the steric hindered effect. The monomers M ₁ , M ₄ , and M ₅ did not reveal mesomorphic properties because of the weaker rigid core or the longer flexible terminal groups, whereas M ₂ , M ₃ , and M ₆ all revealed cholesteric phase. Except P ₄ and P ₅ , the homopolymers P ₁ – P ₃ and P ₆ showed a smectic A phase. In addition, melting, glass transition temperature, or clearing temperature increased, and the mesophase temperature range widened with increasing the rigidity of mesogenic core or decreasing the length of the flexible spacer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

侧链液晶聚硅氧烷的研究进展

侧链液晶聚硅氧烷是一类极具发展前景的新型功能材料,它具有独特的光学、电磁学、黏温特性及较好的机械性能,可用于色谱分离、生物材料、光电信息存贮材料等方面。综述了近年来国内外侧链液晶聚硅氧烷的研究进展,对几种主要类型的侧链液晶聚硅氧烷,即近晶型、向列型、胆甾型以及鱼骨型作了较全面的总结,并对其在色谱分离、生物材料、光电信息存贮材料等方面的应用进行了详细的介绍,最后对其目前的现状作了总结,并对其应用前景进行了展望。     

表面摩擦对反射式胆甾相液晶显示器件对比度的影响

主要通过p态和fc态的反射特征曲线来研究取向层的摩擦强度对胆甾相液晶显示器件对比度的影响。随着摩擦强度的增大,器件的对比度先增大后减小,在摩擦强度为25.26mm时,器件的对比度达最大,约为5.66。结果表明,对取向层进行适当的摩擦处理,可以得到对比度较高的显示器件。