Photoswitchable Spirobenzopyran‐ Based Photochemically Controlled Photonic Crystals

We have developed a photochemically controlled photonic‐crystal material by covalently attaching spiropyran derivatives to polymerized crystalline colloidal arrays (PCCAs). These PCCAs consist of colloidal particles that self‐assemble into crystalline colloidal arrays (CCAs), which are embedded in crosslinked hydrogels. Photoresponsive PCCAs were made two ways: 1) by functionalizing the hydrogel network with spiropyran derivatives, and 2) by functionalizing the colloidal particles with spiropyran derivatives. These materials can diffract light in the UV, visible, or near‐IR spectral regions. The diffraction of the PCCAs is red‐shifted by exciting the spiropyran with UV light. Alternatively, the diffraction is blue‐shifted by exciting the spiropyran with visible irradiation. Thus, this material acts as a memory storage material where information is recorded by illuminating the PCCA and information is read out by measuring the photonic‐crystal diffraction wavelength. UV excitation forms the open spiropyran form while visible excitation forms the closed spiropyran form. The diffraction shifts result from changes in the free energy of mixing of the PCCA system as the spiropyran is photoexcited to its different stable forms.     

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

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。     

透明液晶显示器色度特性研究

透明显示器适用于建筑物窗户、汽车车窗与商店橱窗等多种应用,除了原有的透明显示功能以外,还具有未来可能作为信息显示器的发展潜力,因而备受市场关注.但是目前厂商开发的重点仅集中在如何提高透明液晶面板的全光透过率,而对其色度特性研究却很少,导致在实际应用上全光透光率高的产品,其背后物品的色彩显示并不准确,应用效果不理想.在本文中,我们采用本公司量产的315UV2A透明液晶面板,对不同颜色光线通过透明显示器时的色度坐标偏移情况进行研究,确定了透明显示器对色度的影响.     

一种新型的聚合物网络胆甾液晶显示器

在胆甾液晶材料中掺入少量的聚丙烯类单体材料制作了一种新型的聚合物网络胆的液晶显示器。相对于传统的ＰＤＬＣ器件，这种新型显示器可以进行反模式显示，零电场时呈透明态，加电场呈散射态．而且还具有非常宽阔的视角特性。文中报道了器件的制作方法以及聚合物网络对器件电光特性的影响，并且对该器件的应用前景作了简要介绍。     

聚合物分散液晶膜的弯曲散射偏光效应

实验制备了聚合物分散液晶(PDLC)电控调光膜样品 。测试结果表明,样品散射雾度90%以上;施加电场透明透光率接近 80%;施加弯曲应力半透明最大透光率30%以上。分析了样品施加应力 后出现的弯 曲散射偏光现象,弯曲应力导致双极构型的双极连线有沿弯曲方向的大致沿面取向,使 得液晶 微滴中液晶分子有沿面大致取向,导致液晶微滴的折射率沿弯曲方向与聚合物折射率差别大 造成光散射,而沿垂直弯曲方向与聚合物折射率相等造成光透射。     

一种用于液晶分子取向排列的紫外光聚合物PV4研究

研究了紫外光聚合物材料ＰＶ４的化学性质;采用偏光显微照相技术,研究厂这种材料膜对液晶ＬＣ－６７１０Ａ的取向能力;用原子力显微镜（ＡＦＭ）,研究了光聚合前后聚合物取向膜微观形貌的变化;测最了这种材料引起的液晶预倾角、单面光控取向层扭曲向列液晶显示器件（ＴＮ－ＬＣＤ）的电光特性和时间响应特性;分析了液晶分子取向排列的机理。     

应变液晶调光显示有机玻璃制品的制备及其应用

为将应变液晶调光显示应用于小尺寸显示领域,特选用比重较小、机械强度较高的有机玻璃材料来制作样品。制作基于应变液晶原理。在样品制备时,采用卡通图案遮挡部分区域,进行初次强光较短时间曝光,得到有卡通图案的制品,遮光处形成透明状态,无遮光部位处于散射状态;撤掉掩膜再进行第二次弱光较长时间曝光,原透明处变弱散射半透明,原散射处充分固化变强散射部位。样品未受外力时,无遮光部分透过率低,遮光部分透过率高,形成显示;对制品施加剪切应力,整个制品变成半透明状态,遮光部分和无遮光部分透过率均较高,显示图案消隐。有机玻璃样品比玻璃样品更适合制造玩具和旅游纪念章、会展吉祥物等小商品,具有广泛的应用前景。     

Electrochromic Polymer‐Dispersed Liquid‐Crystal Film: A New Bifunctional Device

Polymer‐dispersed liquid crystals (PDLCs) are liquid‐crystal dispersions within a polymer matrix. These films can be changed from an opaque to a transparent state by applying a suitable alternating‐current electric field. PDLCs have attracted the interest of researchers for their applications as light shutters, smart windows, and active displays. For such applications, electrochromic devices, which change color as a result of electrochemical reactions, have also become a recent focus of research. Herein, we report our preliminary results on bifunctional devices based on PDLCs that host electrochromic guest molecules. Such devices allow both an independent and fast switching from a scattering opaque state to a transmissive transparent state owing to liquid‐crystal reorientation and a color change from white (pale yellow) to dark blue, due to either oxidation or reduction of the electrochromic molecules.     

光控取向弱锚定表面的液晶分子排列

研究了光敏聚酰亚胺ＰＩ（ＢＴＤＡ－ＴＭＭＤＡ）用于液晶取向时的弱锚定边界特性。实验测得了两基板皆为摩擦取向层扭曲向列液晶显示器件（ＤＲ－ＴＮ－ＬＣＤ）及两基板皆为光控取向层的扭曲向列液晶显示器件（ＤＬＰＰ－ＴＮ－ＬＣＤ）的电光特性和时间响应特性曲线。研究了液晶排列的稳定性,讨论了液晶分子在光控取向弱锚定表面上的排列机理。     

一种光学状态可由电场控制的液晶复合材料的制备与表征

液晶材料对电、热、磁、光等外界物理量的变化具有不同的响应特性,向其中添加具有一定特性的化合物,可以得到具备一定响应特性的液晶复合材料。利用所制备的液晶复合材料对于电场变化具有响应特性的特点,制备出具有信息记录功能的复合材料。合成手性离子液体,按一定配比将其加入手征向列相液晶(N~*-LC)中,得到反射波段可电控的手征向列相液晶/手性离子液体复合材料。实验结果表明:材料初始状态为光透射状态;对材料施加直流电压40V时,样品表现为光散射状态,透过率低于10%;施加高频交流电压40V时,样品表现为半透明镜面反射,反射范围覆盖400～750nm,透射率为45%左右;撤去电场后,可恢复至初始状态,并且每种状态都具有一定的记忆效应。该种液晶复合材料制备简单,无需紫外辐射工艺,且具有电场响应特性,可以通过电场控制在可见光范围内表现出光透射、强烈光散射、半透明镜面反射3种不同状态,具有记忆效应,操作简单方便。     

Graphene Oxide Based Transparent Resins For Accurate 3D Printing of Conductive Materials

Digital Light Processing (DLP) allows the fast realization of 3D objects with high spatial resolution. However, DLP is limited to transparent resins, and therefore not well suited for printing electrically conductive materials. Manufacturing conductive materials will significantly broaden the spectrum of applications of the DLP technology. But conductive metals or carbon-based fillers absorb and scatter light; inhibiting thereby photopolymerization, and lowering resolution. In this study, UV transparent liquid crystal graphene oxide (GO) is used as precursor for generating in situ conductive particles. The GO materials are added to a photopolymerizable resin via an original solvent exchange process. By contrast to earlier contributions, the absence of drying during the all process allows the GO material to be transferred as monolayers to limit UV scattering. The absence of UV scattering and absorption allows for fast and high-resolution 3D printing. The chosen resin sustain high temperature to enable an in situ efficient thermal reduction of GO into reduced graphene oxide (rGO) that is electrically conductive. The rGO particles form percolated networks with conductivities up to 1.2 × 10⁻² S m⁻¹. The present method appears therefore as a way to reconcile the DLP technology with the manufacturing of 3D electrically conductive objects.     

聚合物分散液晶透明投影屏幕成像原理研究

对施加电场时呈透明态(ON态)的聚合物分散液晶(PDLC)膜用作透明投影屏幕的原理给出定性与定量的描述和分析。在PDLC-ON态测试样品的透光率随入射角变化曲线,发现S偏振光透光率不受PDLC膜的影响,P偏振光透光率随入射角变化受PDLC膜的影响衰减严重,发生散射。建立了P偏振光透光率随入射角度变化物理模型,给出了P偏振光的透光率的表达式。模拟计算得出理论曲线,与实验曲线相符合,进而解释了PDLC-ON态作为透明投影屏幕的成像原理。     

Photopatterning Freestanding Chiral Nematic Mesoporous Organosilica Films

Chiral nematic mesoporous organosilica (CNMO) films are functionalized with a mixture of hydrophobic silanes and spiropyran compounds to create freestanding photochromic films that can be used for reversible photo­patterning. The mesoporosity and interconnected pore structure of the films imparted by the cellulose nanocrystal template enables a large cross‐section of the material to be functionalized. Thus, the materials show intense absorption spectra from the tethered spiropyran and rapid color changes when the porous films are irradiated with UV or white light. The spiropyran‐bound CNMO films behave as reversible sensors where metal binding to the spiropyran results in visible color changes detectable by the naked eye. These metals can be removed in the presence of ethanol and white light, regenerating the metal‐free film. The proof‐of‐concept demonstrated in this paper may help to develop new photochromic displays, security features, and patterns.     

液晶微胶囊制备宽波反射凝胶

手征向列相(N*)液晶能够选择性反射入射光,但其反射波宽一般小于150nm。利用负介电各向异性的向列相液晶SLC10V513-200与手性化合物R1011、CB15配制出5种N*液晶,其反射波长能够覆盖整个可见光波段。使用异佛尔酮二异氰酸酯(IPDI)界面聚合法制备出平均粒径为8.0μm的5种N*液晶聚脲微胶囊之后,将相同质量的5种微胶囊混入OP-10与IPDI中制备出微胶囊的凝胶。对80.0μm厚微胶囊凝胶薄膜施加交流电场,使微胶囊中的液晶处于平面织构状态,紫外固化微胶囊中的液晶性单体,固定微胶囊中N*液晶的平面织构,从而制备出可以反射可见光波段的微胶囊凝胶薄膜。     

A liquid-vapor display

A new reflective display principle is described. A roughened glass surface wetted with a transparent volatile liquid of the same refractive index as the glass acts as a transparent medium. The electrical heating, via transparent electrodes, of a thin film of liquid adjacent to the roughened surface transforms the glass into a light scattering surface. The fundamental thermal, electrical, and optical characteristics of the display element are reported. Schemes are described for building simply constructed flat panel arrays of liquid-vapor display elements. Such displays are capable of gray scale, can be designed to have frame-time or permanent memory, and can be matrix addressed by electronic, thermal, or geometric means.     

Electrohydrodynamic NanoDrip Printing of High Aspect Ratio Metal Grid Transparent Electrodes

The transparent conducting electrode is an essential component in many contemporary and future devices, ranging from displays to solar cells. Fabricating transparent electrodes requires a balancing act between sufficient electrical conductivity and high light transmittance, both affected by the involved materials, fabrication methodology, and design. While metal films possess the highest conductivity at room temperature, a decent optical transmittance can only be achieved with ultrathin films. Structuring the metal into optically invisible nanowires has been shown to be promising to complement or even substitute transparent conductive oxides as dominant transparent electrode material. Here the out‐of‐plane fabrication capability of the recently developed method of electrohydrodynamic NanoDrip printing to pattern gold and silver nanogrids with line widths from 80 to 500 nm is demonstrated. This fully additive process enables the printing of high aspect ratio nanowalls and by that significantly improves the electrical performance, while maintaining the optical transmittance at a high level. Metal grid transparent electrodes optimized for low sheet resistances (8 Ω sq^?1 at a relative transmittance of 94%) as well as optimized for high transmittance (97% at a sheet resistance of 20 Ω sq^?1) are reported, which can be tailored on demand for the use in various applications.     

聚合物网络稳定液晶的电光偏振片

采用类似宾主效应法,在１Ｔ高斯的磁场中合成了聚合物网络稳定液晶膜。这种膜在关态呈透明态,且具有取向呈各向异向性。研究表明,在适度电场作用下。这种膜可呈现强的光散射各向异性,即光偏振性。用建立的结构模型分析和讨论了实验的结果。     

Performance characteristics of nematic liquid crystal display devices

Display devices using nematic liquid crystal materials offer advantages over other display media in low-voltage low-power operation, cost of materials and fabrication methods, electrical compatibility with MOS drive circuits, and flexibility of character size and format. This paper describes liquid crystal display devices that utilize dynamic scattering to modify transmitted or reflected light. We have synthesized individual materials that have nematic temperature ranges as large as -15-115°C without super-cooling effects at low temperatures. When these materials are used in transmissive displays having liquid crystal layers 12 µm thick sandwiched between transparent electrodes, contrast ratios of 30:1 to 50:1 are realized at 10-40 V dc or ac with a current density of ∼1-10 µA/cm². Turn-on times are 10-50 ms and turn-off times are 30-100 ms, precise values being dependent on the specific material, temperature, and voltage used. The contrast ratio versus voltage exhibits a threshold so that it may be possible to matrix address liquid crystal display panels. Operating lifetime and display applications are also discussed.     

Reversible Quadruple Switching with Optical,Chiroptical, Helicity,and Macropattern in Self‐Assembled Spiropyran Gels

Enantiomeric glutamate gelators containing a spiropyran moiety are designed and found to self‐assemble into a nanohelix through gelation. Upon alternating UV and visible light irradiation, the spiropyran experiences a reversible change between a blue zwitterionic merocyanine state and a colorless closed ring state spiropyran in supramolecular gels. This photochromic switch causes a series of subsequent changes in the optical, chiroptical, morphological properties from supramolecular to macroscopic levels. While the solution of the gelator molecules does not show any circular dichroism (CD) signal in the region of 250–700 nm due to the fact that the chromophore is far from the chiral center, the gel shows chiroptical signals such as CD and circularly polarized luminescence (CPL) because of the chirality transfer by the self‐assembly. These signals are reversible upon alternating UV/vis irradiation. Therefore, a quadruple optical and chiroptical switch is developed successfully. During such process, the self‐assembled nanostructures from the enantiomeric supramolecular gels also undergo a reversible change between helices and fibers under the alternating UV and visible light trigger. Furthermore, a rewritable material fabricated from their xerogels on a glass is developed. Such rewritable material can be efficiently printed over 30 cycles without significant loss in contrast and resolution using UV and visible light.     

添加剂对高双折射液晶紫外稳定性影响

高双折射液晶在液晶显示中具有重要的应用价值,但是由于分子结构中含有不饱和共轭结构,在紫外下不稳定,本文对高双折射液晶紫外不稳定的问题进行了研究。首先在混晶母体A中分别加入几种不同结构的添加剂三苯氧膦、丙基双环己基甲醛、丙基苯(3,5-2F)溴苯、UV-P,搅拌使其溶解均匀,将液晶灌入TN-7.0-R测试盒,在紫外下曝光后测试混晶的各项参数。实验结果表明:UV-P明显提高了高双折射液晶的抗紫外性能,因为UV-P的紫外吸收光谱带与高双折射液晶母体A的紫外吸收光谱带最接近。