共查询到20条相似文献,搜索用时 125 毫秒
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日本熊本大学工程系的中武裕一朗等研究人员新近研制成具有架桥结构的液晶聚合物网络构成的全息光栅。实现了快速写入、擦除、高密度光学信息记录。研究人员制作了侧链型偶氮苯的液晶聚合物网络。研究了架桥密度和偶氮苯含量对衍射效率的影响。首先在单丙烯酸盐单体 APB6中 ,作为架桥剂掺入了双丙烯酸盐单体A6 PB6 A,作为光响应性分子添加了 DRLac。作为这种混合液晶的聚合引发剂加入了2 mol%的 2 .2 -二甲氧基 -2 -苯基苯乙酮 ,然后在间隙为 5μm的水平取向处理的盒中以向列相状态进行光聚合 (1 1 m W) 3min,制成光响应性液晶网络。并… 相似文献
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正模式聚合物网络稳定的胆甾相液晶显示器的研究 总被引:2,自引:2,他引:0
采用由胆甾相液晶(Δε>0)和在光照条件下可发生交联的双丙烯酸酯类单体组成的混合物,在加电压的状态下用紫外光固化制成的聚合物网络稳定的胆甾相液晶显示器件,可实现零电场的焦锥织构(F态)散射态和加电场的垂直排列(H态)透明态的转变。系统研究了不同的单体含量、手性剂含量、UV光强等对器件电光特性的影响,用SEM研究了聚合后的网络形貌。 相似文献
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利用差示扫描量热仪(DSC)、显微热分析仪和偏光显微镜(POM)对系列侧向氟取代双烷基环己基联苯类液晶的介晶性进行了系统研究。结果表明,所有化合物均有介晶性。在液晶态可观察到部分单体的近晶C相(SC)、近晶B相(SB)、近晶A相(SA)和所有单体向列相的典型织构。与相应的4,4′-双-(烷基环己基)联苯类液晶相比,引入侧向氟取代基以后近晶相温度区间明显减小,向列相温度区间增加。 相似文献
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采用柔性的双官能团聚合物单体二丙烯酸酯NPGDA,将掺杂这种单体含量为2%(质量分数)的铁电液晶在SmA*相下用UV光照,制备了聚合物网络稳定铁电液晶样品。原子力显微镜给出NPGDA在样品中形成了具有各向异性、沿着基板摩擦方向延伸的聚合物网络。利用偏光显微镜和液晶参数综合测试仪对该样品进行观察测试,实验检测结果表明,由于聚合物网络体锚定的引入,使得铁电液晶分子在电场下的运动受到限制,得到了均匀取向的条纹织构,避免了zigzag缺陷,且该器件的电光曲线为“V”字形,从而实现了连续灰度,对比度达到199∶1,饱和电压为6V,上升时间和下降时间分别为494μs和404μs,同时铁电液晶器件的抗震动能力得到了显著提高。 相似文献
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日本熊本大学的中屿洋平等研究人员通过将单丙烯酸盐性和双丙烯酸盐性液晶单体及偶氮苯分子的混合液晶在向列相温度下按单轴取向状态聚合,制作成光响应液晶网络结构,并研究了其光开关行为,基于双折射发生变化的开关响应及下降时间为数微秒到几百微秒,寻求原因,发现在光开关过程中出现很强的架桥密度效应,架桥在一定程度上抑制了分子运动幅度,使开关速度加快,此外,将成分相同的混合液晶做成两样品,一是在向列相状态下进行取向处理,同时进行光聚合;二是处于摩擦处理过的玻璃基板间,使其平行取向,然后光取合,所获得的网络结构进行X光衍射时,发现两样品中都存在近晶相峰,此峰与未经取向处理的聚合效率比,峰高显著增大,由此说明,控制起始分子取向性的环境中聚合,可制作近晶相为主的网状结构。 相似文献
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合成了大螺旋扭曲力的手性化合物4,4′-2(戊基-环己基)苯甲酸异山梨醇酯(ISBB)。对60.0μm厚ISBB/液晶性单体/向列相液晶/光引发剂复合体系的液晶层的上、下表面温度施加不同温度,液晶层中形成了温度梯度。由于高温区域的液晶溶解ISBB的能力强,低温区域的ISBB会向高温区域扩散,从而在液晶薄层中形成了ISBB的浓度梯度与螺距梯度。紫外光聚合复合体系中的光可聚合单体,单体间交联聚合形成网络固定住了液晶层内的螺距梯度,从而制备出反射可见光波段的右旋圆偏振光的宽波反射液晶薄膜。 相似文献
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研制出一种明亮的全色反射型LCD称作IRIS,即反向散射型内反射。IRIS具有2独特的聚合物-液晶混合结构,在这种结构中,定向聚合物微粒弥散在液晶中。通过研究聚合物单体,液晶材料及紫外光聚合过程,这种混合体系能满足有源LCD所需的足够的电阻率,热稳定性和光稳定性。 相似文献
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M. Hckel L. Kador D. Kropp C. Frenz H.‐W. Schmidt 《Advanced functional materials》2005,15(10):1722-1727
Diblock copolymers, consisting of a photoaddressable mesogen‐containing dispersed phase and a polystyrene matrix, have been synthesized and characterized as holographic data storage materials. The photoaddressable phase contains p‐methoxy‐substituted azobenzene side groups and benzoylbiphenyl mesogenic side groups in a statistical distribution. Three‐ring mesogenic groups in combination with photoaddressable azobenzene side groups have been introduced for the first time in block copolymers in order to increase the local refractive‐index difference between illuminated and non‐illuminated volume elements, as well as to improve the stability of the orientation, while, at the same time, decreasing the optical density. To this end, a series of block copolymers with different azobenzene/mesogen ratios have been synthesized. The light‐induced reorientation dynamics of the chromophores and mesogens and the long‐term stability of the orientation have been studied with volume holographic measurements. A remarkable increase in stability of the holographic gratings has been achieved. 相似文献
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《Display Technology, Journal of》2008,4(4):369-376
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S. Abraham S. Paul G. Narayan S.K. Prasad D.S.S. Rao N. Jayaraman S. Das 《Advanced functional materials》2005,15(10)
A chiral liquid‐crystalline phase is reported for the first time in sugar‐based mesogens containing free hydroxyl groups by Jayaraman, Das, and co‐workers. Earlier reports have shown that hydrogen‐bonding networks between hydroxyl groups in mesogenic sugars usually result in the manifestation of achiral smectic and columnar phases. The results reported on p. 1579 indicate that the manifestation of smectic C* phases in sugar‐based bolaamphiphiles depends critically on the length of the methylene spacers and the presence of the azobenzene chromophore. Amphiphilic sugars exhibit both lyotropic and thermotropic liquid‐crystalline behavior. Interestingly, in spite of the abundance of chiral centers in amphiphilic sugars, their liquid‐crystalline phases do not exhibit macroscopic chirality. Herein, we report on the first observation of macroscopic chirality in sugar‐based bolaamphiphiles containing free hydroxyl groups. The manifestation of the chiral smectic C* phase in these bolaamphiphiles has been observed to be critically dependent on the presence of the azobenzene moiety and the suitable length of the methylene spacer. These results imply that by suitable selection of linker groups, mesogenic bolaamphiphiles possessing macroscopic chirality can be designed using a variety of naturally available sugar derivatives. 相似文献
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Eric Głowacki Karen Horovitz Ching W. Tang Kenneth L. Marshall 《Advanced functional materials》2010,20(17):2778-2785
We have fabricated switchable gas permeation membranes in which a photoswitchable low‐molecular‐weight liquid crystalline (LC) material acts as the active element. Liquid crystal mixtures are doped with mesogenic azo dyes and infused into commercially available track‐etched membranes with regular cylindrical pores (0.40 to 10.0 μm). Tunability of mass transfer can be achieved through a combination of (1) LC/mesogenic dye composition, (2) surface‐induced alignment, and (3) reversible photoinduced LC‐isotropic transitions. Photo‐induced isothermal phase changes in the imbibed material afford large and fully reversible changes in the permeability of the membrane to nitrogen. Both the LC and photogenerated isotropic states demonstrate a linear permeability/pressure relationship, but they show significant differences in their permeability coefficients. Liquid crystal compositions can be chosen such that the LC phase is more permeable than the isotropic—or vice versa – and can be further tuned by surface alignment. Permeability switching response times are 5 s, with alternating UV and >420‐nm radiation at an intensity of 2 mW/cm2 being sufficient for complete and reversible switching. Thermal and kinetic properties of the confined LC materials are evaluated and correlated with the observed permeation properties. We demonstrate for the first time reversible permeation control of a membrane with light irradiation. 相似文献
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S. Abraham S. Paul G. Narayan S.K. Prasad D.S.S. Rao N. Jayaraman S. Das 《Advanced functional materials》2005,15(10):1579-1584
Amphiphilic sugars exhibit both lyotropic and thermotropic liquid‐crystalline behavior. Interestingly, in spite of the abundance of chiral centers in amphiphilic sugars, their liquid‐crystalline phases do not exhibit macroscopic chirality. Herein, we report on the first observation of macroscopic chirality in sugar‐based bolaamphiphiles containing free hydroxyl groups. The manifestation of the chiral smectic C* phase in these bolaamphiphiles has been observed to be critically dependent on the presence of the azobenzene moiety and the suitable length of the methylene spacer. These results imply that by suitable selection of linker groups, mesogenic bolaamphiphiles possessing macroscopic chirality can be designed using a variety of naturally available sugar derivatives. 相似文献
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在全息聚合物分散液晶的预聚物体系中添加含氟的单丙烯酸酯单体,制备全息聚合物分散液晶Bragg光栅,通过AFM、He-Ne激光器观察分析,发现甲基丙烯酸十二氟庚酯(Actyflon-G04)的添加不仅改善聚合物基质的形貌,同时也影响光栅的电光特性。实验结果表明,光栅的衍射效率从78%上升到90%,驱动电压V90大幅降低。分析认为,Actyflon-G04的添加降低了聚合物界面的表面张力,影响液晶微滴的分子取向,从而实现了光栅电光特性的改善。 相似文献
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液晶含量对聚合物/液晶复合膜电光特性的影响--从正型向反型显示模式的转变 总被引:3,自引:2,他引:1
预聚物与正性液晶以适量配比合成的聚合物/液晶复合膜通常呈正型显示,即膜在关态时呈散射态,在开态时呈透射态。然而实验发现,用高的液晶配比合成的膜在适度电压驱动下能呈现反型显示,即这种膜在关态时呈透射态,在适度电压作用下呈散射态。在制膜过程中,如能将液晶做沿面取向处理,则膜的反型效应更加明显。用聚合物/液晶复合膜的反型显示机理,可开发出一系列新的光学显示器件。本实验研究了这种反型模式器件的电光特性,并建立相关的结构模型解释了实验结果。 相似文献
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Wenbin Huang Zhihui Diao Yonggang Liu Zenghui Peng Chengliang Yang Ji Ma Li Xuan 《Organic Electronics》2012,13(11):2307-2311
Distributed feedback polymer laser with a grating in the waveguide cladding layer was prepared by holographic polymer dispersed liquid crystals (HPDLCs). The holographic polymerization technique enables one-step formation of an organic grating on top of a homogenous semiconducting polymer poly(2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV) layer. Under optical pumping, a lasing threshold of 21 μJ/cm2 and a bandwidth of 0.7 nm were obtained in a single longitudinal mode operation. Further studies on the effect of the semiconducting polymer thickness show the amount of evanescent wave spread into the grating layer determines the laser performance of the proposed device. 相似文献
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In this report, we show that the microstructures of hydrogen‐bonded side‐chain liquid‐crystalline block copolymers can be rapidly aligned in an alternating current (AC) electric field at temperatures below the order–disorder transition but above the glass transition. The structures and their orientation were measured in real time with synchrotron X‐ray scattering. Incorporation of mesogenic groups with marked dipolar properties is a key element in this process. A mechanism related to the dissociation of hydrogen bonds is proposed to account for the fast orientation switching of the hydrogen‐bonded blends. 相似文献