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首页> 外文期刊>Clay science >APPLICATION OF LAYERED INORGANIC MATERIALS IN RECTIFICATION OF ELECTRO-OPTICAL PROPERTIES OF NEMATIC LIQUID CRYSTALS ANDTOLYMER-ENCAPSULATED LIQUID CRYSTALS
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APPLICATION OF LAYERED INORGANIC MATERIALS IN RECTIFICATION OF ELECTRO-OPTICAL PROPERTIES OF NEMATIC LIQUID CRYSTALS ANDTOLYMER-ENCAPSULATED LIQUID CRYSTALS

机译：层状无机材料在整形液态液晶和高分子包封液态液晶电光特性中的应用

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摘要

The electro-optical (EO) properties were measured for cells composed of layered inorganic materials; i.e., either the smectite sodium montmorillonite (MMT) or layered double hydroxides (LDHs), as an additive in the organic nematic liquid crystal (NLC) E7 or blends of E7 and a photoinduced polymer. For a twisted NLC (TNLC) device driven by an applied voltage, the smectite hybridized into the LC was found to suppress the formation of electric bilayers and the field-screening effect, significantly reducing the ion-charge concentration down to as low as ~1% for a TNLC—clay cell containing —0.5 wt% MMT1'2'. Similar results were also observed from the LC-clay nanocomposite confined in a homogeneously-aligned cell3'. On account of the clay platelets and NLC molecules being aligned by the externally applied voltage and the nanoplatelets homogeneously dispersed in the NLC hydrosol, the voltage-transmittance curve of the hybrid cell exhibited increasing contrast ratio of the LC photonic device. Besides, the voltage-capacitance characterization indicated that the layered inorganic clay in E7, depending strongly on the proper charge properties such as charge affinity of the layered materials itself, was able to dramatically decrease the threshold voltage for cells of TNLC-clay composites operated by dc electric field. Consequently, adding an appropriate amount of clay substantially rectified the EO switching properties of a typical low-resistivity NLC in the TNLC-clay hybrid materials system. On the other hand, holographic polymer-dispersed LCs (H-PDLCs) consisting of E7 and layered inorganic materials in photo-polymerized macromolecular matrices were investigated. The H-PDLC were fabricated from a monomer hybrid solution including dipentaerythritol pentaacrylate (SR399), cross-linking iV-vinyl-pyrrollidone (NVP), photo-initiator dye Rose Bengal (RB), co-initiator N-phenylglycine (NPG) and E7 by wave mixing of two coherent argon-ion laser beams at the 514.5 nm line4'5'. Due to the photo-induced polymerization phase separation, the NLC-polymer blends were separated into mesophase and polymer phase and the role of clay as a dopant in the phase separation processes could be established by observing the morphologies of the composite films and the resulting performance of the cells. The effect of MMT doping in the NLC-polymer systems was first revealed by the wide-angle X-ray diffraction pattern, indicating that the liquid-crystalline signal was enhanced by doping various clays at adequate contents. Further evidence was manifested by the increases in both the range of the size distribution and the maximum size of the NLC droplets with increasing clay content up to 3 wt%, as examined with a transmission electron microscope as well as a field-emission scanning electron microscope after the cell substrates were taken apart and E7 droplets was removed from the PDLCs4'6>. We found the PDLC comprising 3 wt% clay with higher cation exchange capacity (168 meq per 100 g of clay in this study) to be dramatic in particular to lower the driving voltage, switching time and threshold voltage simultaneously and to suffer less serious off-axis haze at large angles of incidence in general6'. For H-PDLCs, self-diffraction experiments in the Raman-Nath regime showed that the first-order diffraction efficiency was enhanced in those consisting of pristine MMT nanoparticles and yet depressed by the incorporation of organophilic MMT5'. Holographic nature of the nanocomposites with polymeric matrices was confirmed by optical polarizing microscopy5). Without the use of an applied voltage, the 5-phr-clay-hybridized and 1-phr-LDH-doped nanocomposites yielded the improved first-order diffraction efficiencies of 6 times and 4 times higher than that of the pristine H-PDLC counterpart, respectively5'7'. In contrast, the diffrac- tion efficiency of the phase gratings recorded in the cells of E7 hybridized with 1 wt% MMT clay was found to be only three times higher than that in the pristine cell when a dc electric field of 0.5 V/μm was applied.
机译：测量了由层状无机材料组成的单元的电光（EO）性能；即蒙脱石钠蒙脱土（MMT）或层状双氢氧化物（LDHs），作为有机向列液晶（NLC）E7中的添加剂或E7与光致聚合物的共混物。对于由施加电压驱动的扭曲NLC（TNLC）器件，发现与LC杂化的蒙脱石可抑制双电层的形成和电场屏蔽效应，从而将离子电荷浓度显着降低至低至〜1对于含有-0.5 wt％MMT1'2'的TNLC-粘土电池，其含量为％从限制在均匀排列的单元中的LC粘土纳米复合材料也观察到了相似的结果。由于通过外部施加的电压使粘土血小板和NLC分子对齐，并且纳米薄片均匀分散在NLC水溶胶中，混合电池的电压-透射率曲线显示出LC光子器件的对比度增加。此外，电压电容特性表明，E7中的层状无机粘土强烈地依赖于适当的电荷特性（例如层状材料本身的电荷亲和力），能够显着降低由TNLC-粘土复合材料制成的电池的阈值电压。直流电场。因此，在TNLC-粘土混合材料系统中，添加适量的粘土可显着改善典型的低电阻NLC的EO转换性能。另一方面，研究了由E7和层状无机材料组成的全息聚合物分散LC（H-PDLC）在光聚合大分子基质中的存在。 H-PDLC由单体杂化溶液制成，该溶液包括二季戊四醇五丙烯酸酯（SR399），交联的iV-乙烯基吡咯烷酮（NVP），光引发剂染料Rose Bengal（RB），共引发剂N-苯基甘氨酸（NPG）和通过在514.5 nm线4'5'处将两个相干的氩离子激光束进行波混合来实现E7。由于光诱导的聚合相分离，NLC-聚合物共混物被分离为中间相和聚合物相，通过观察复合膜的形态和所产生的性能，可以确定粘土在相分离过程中作为掺杂剂的作用。的细胞。首先通过广角X射线衍射图揭示了MMT在NLC-聚合物体系中的掺杂效果，表明通过以适当的含量掺杂各种粘土可以增强液晶信号。用透射电子显微镜和场发射扫描电子显微镜检查，随着粘土含量增加至3 wt％，NLC液滴尺寸分布范围和最大尺寸的增加，也进一步证明了这一点。在将细胞底物拆开并从PDLC 4'6>中除去E7液滴之后。我们发现，PDLC包含3 wt％的粘土，具有较高的阳离子交换容量（本研究中每100 g粘土为168 meq），特别是在降低驱动电压，切换时间和阈值电压的同时，降低了严重的关断性。轴通常以大入射角雾度6'。对于H-PDLC，在拉曼-纳特（Raman-Nath）体制中的自衍射实验表明，在由原始MMT纳米颗粒组成的分子中，一级衍射效率得到了提高，但由于掺入亲有机性MMT5'而降低了。纳米复合材料与聚合物基体的全息性质通过光学偏振显微镜得到证实。在不使用施加电压的情况下，掺有5phr粘土和1phr-LDH的纳米复合材料的一阶衍射效率比原始H-PDLC同类产品高出6倍和4倍，分别为5'7'。相反，发现在E7的电池中，与1 wt％的MMT粘土混合时，所记录的相位光栅的衍射效率仅比原始电池中的0.5 V /μm直流电场高3倍。应用。

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  • 来源
    《Clay science》 |2011年第2期|p.67-74|共8页
  • 作者

    Tsung-Yen Tsai; Chun-Yi Lee; Wei Lee;

  • 作者单位

    Department of Chemistry and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan, Republic of China;

    Department of Chemistry and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan, Republic of China;

    Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan, Republic of China;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    layered materials; nematic liquid crystals; tnlc device; h-pdlcs; electro-optical properties.;

    机译：分层材料;向列型液晶;tnlc设备;h-pdlcs;电光特性。;

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