液晶光定向层材料

本文综述了近10年来液晶显示用光定向层材料领域的研究现状和进展情况，主要概述了光降解型、光致异构型、光交联型以及自组装等材料，并对目前报道的液晶光定向机理进行了总结和归纳。     

一种光交联电光聚合物的合成及其外部电光测量

合成了一种新的带有光交联基团的电光聚合物,其高分子基体是双酚A环氧树脂,二阶非线性生色团对硝基苯胺和光交联基团肉桂酰氯都键接在高分子链上.将聚合物溶解后旋涂成膜,对薄膜进行电晕极化.极化的后阶段用紫外光照射,使聚合物体系交联成网络结构,形成生色团取向长时间稳定的聚合物电光薄膜.用这种聚合物电光薄膜构成外部电光调制系统,测量了共面波导上的电信号.     

光栅立体影像的技术进展

人类处于三维世界之中.用我们一双明亮的眼睛能够辨别周围物体所处的相对空间位置,感受这美妙的立体世界.但是,至今广泛采用的照相术,只能记录平面影像,缺乏真实感.立体影像是继平面影像的自然演进.大约30年前,东京大学教授大越孝敬在他1976年的著作《三次元画像工学》里提到"重建空间影像是人类的梦想".其实,这个梦想早已开始,F.E.Ives于1903年已发表利用光栅的立体影像原理.光栅立体影像的应用发展始于1940年,至今已有60多年历史,但一直都未能普及化,一定有其中的原因.     

电子供体影响Cr(VI)光还原速度的ESR/全息法研究

分别用电子自旋共振(ESR)法和全息法研究了六价铬离子Cr(VI)在不同电子供体─-二甲基亚砜(DMSO)和N,N′-二甲基甲酰胺(DMF)──作用下向三价铬离子Cr(Ⅲ)的光转换速度。两种方法得到相同的结论:DMSO和DMF都不同程度地加速了Cr(VI)的光致还原速度,DMSO的效果更加显着。     

Dual Photo‐functionalized Amphiphile for Photo‐reversible Liquid Crystal Alignments

Without the conventional polymer‐based liquid crystal (LC) alignment process, a newly synthesized dual photo‐functionalized amphiphile (abbreviated as ADMA₁) was successfully applied as a robust photo‐reversible LC alignment layer by self‐assembly and photo‐polymerization. The LC alignment layer constructed by directly adding dual photo‐functionalized amphiphiles into LC media significantly cuts the manufacturing cost as well as opens new doors for the fabrication of novel electro‐optical devices.     

光诱导聚合蒙脱土插层纳米复合材料的研究

用两种光聚合法研究了蒙脱土插层复合材料的制备.用小角X光衍射技术对产物内蒙脱土的结构进行表征,结果表明,蒙脱土经改性后能很好地使聚合单体及预聚物插入黏土层内并在光照下"就地”聚合生成光聚合复合材料.对光聚合法制备蒙脱土纳米复合材料的优缺点进行了初步讨论.     

聚酰亚胺类液晶光定向层材料的研究

经含有羟基的二胺单体HAB与二酐单体 4 ,4′ (六氟异丙基 ) 双邻苯二甲酸酐 ( 6FDA)的缩聚反应 ,制备了含有羟基的先驱聚合物PI OH ,通过PI OH上羟基与肉桂酰氯的酯化反应 ,制备了侧链带有肉桂酸酯基团的光敏聚酰亚胺PI CI.用氢核磁共振 ( 1H NMR)分析、傅立叶红外光谱 (FTIR)分析等表征了上述聚合物的结构与感光性能 .用紫外 可见光谱 (UV Vis)等方法研究了PI CI的光交联反应 .聚合物PI CI旋镀膜经线性偏振光聚合技术 (LPP)处理并装配得到的液晶盒可使液晶分子很好地定向沿面排列 .上述实验表明 ,本文所合成的聚酰亚胺定向层材料是一种新的液晶光定向层材料     

Multichromophoric Organic Molecules Encapsulated in Polymer Nanoparticles for Artificial Light Harvesting

We designed a self‐assembled multichromophoric organic molecular arrangement inside polymer nanoparticles for light‐harvesting antenna materials. The self‐assembled molecular arrangement of quaterthiophene molecules was found to be an efficient light‐absorbing antenna material, followed by energy transfer to Nile red (NR) dye molecules, which was confined in polymer nanoparticles. The efficiency of the antenna effect was found to be 3.2 and the effective molar extinction coefficient of acceptor dye molecules was found to be enhanced, which indicates an efficient light‐harvesting system. Based on this energy‐transfer process, tunable photo emission and white light emission has been generated with 14 % quantum yield. Such self‐assembled oligothiophene–NR systems encapsulated in polymer nanoparticles may open up new possibilities for fabrication of artificial light harvesting system.     

共轭聚合物薄膜中光生载流子的产生及输运机制

对共轭聚合物光生载流子的产生机制进行了初步探讨,分析了由最初产生的电子 空穴对经过晶格驰豫之后形成极化子 激子的热离化过程,认为同一链上的激子会迅速复合,只有链间激子对光电流作出贡献.研究了共轭聚合物中载流子的输运机制,导出了共聚物的电导率公式,其计算值与实验结果符合,我们认为是极化子的链间跃迁实现了整个共聚物的电导和光致发光,较好地解释了实验事实.     

Spectral and photophysical properties, photo and heat resistance of dipyrrolylmethene borofluoride complex and its hybrid material with polymethylmethacrylate

A hybrid material based on polymethylmethacrylate with immobilized borofluoride dipyrrolylmethene complex. The inclusion of the chromophore in the polymer environment is shown to result in a reduced polarization due to the weakening of the forces of intermolecular interactions. Study of spectral properties, photo and thermal stability showed that inclusion of the complex in the polymer matrix can significantly increase the photo and thermal stability and mechanical strength of the material while preserving the spectral characteristics inherent to the individual compound.     

A Photo‐annealing Approach for Building Functional Polymer Layers on Paper

A straightforward photo‐annealing approach was developed for building functional polymer layers on paper. Conducting polyaniline with the ability for photothermal conversion can be readily annealed by near‐infrared light. The annealed polymers become both insulating and hydrophobic. Selective photo‐annealing produces a functional layer with patterned conductive arrays. This material exhibits real‐time response to ammonium gas. Complete photo‐annealing preserves the porous structure but changes the wettability of the polyaniline‐nanofiber film.     

Photo‐alignment material with azobenzene‐functionalized polymer linked in film

Application of a new azo‐polymer as a photo‐alignment material for liquid crystals (LCs) was demonstrated. 4‐(Vinyloxyethyloxy)azobenzene (VAZO), which has thermally reactive vinyl ether groups, reacted with the ? OH groups of poly(4‐hydroxystyrene) (PHS) during the baking process. The azo‐attached polymer (PHS‐VAZO) film showed anisotropic spectra after exposure to 365‐nm linear polarized light (LPL) unlike the VAZO‐doped poly(methylmethacrylate) (PMMA) film. The anisotropy of the film was small at high concentration of the azo‐chromophore because of thermal randomization of the polarized state. In the evaluation of photo‐alignment of the LC, the LC hybrid cell using the PHS‐VAZO film achieved high LC alignment. The azo‐attached polymer using the thermal reaction of vinyl ethers is useful for a photo‐alignment material. Copyright © 2002 John Wiley & Sons, Ltd.     

Photo and thermal polymerization sensitized by donor–acceptor interaction. I. N-vinyl-carbazole–acrylonitrile and related systems

Spontaneous photo and thermal polymerization of N-vinylcarbazole (VCZ)–acrylonitrile (AN), VCZ–acetonitrile, AN-N-ethylcarbazole, and AN-ferrocene were studied. These combinations of electron donor with acceptor were thermally rather stable but showed prominent photopolymerizability when the systems were irradiated by near ultraviolet light. The VCZ–AN system showed multireactivity producing VCZ polymer and a copolymer of VCZ with AN. The composition of copolymer was approximately the same as that of polymer produced in radical copolymerization. The effects of additives (DPPH, NH₃, H₂O, air) indicated simultaneous occurrence of cationic and radical polymerization in the AN–VCZ and acetonitrile–VCZ systems. The results were interpreted on the assumption of initial formation of a cation radical–anion radical pair. The ratio of cationic to radical polymerization differed for photo and thermal polymerization. In no case was anionic polymerization detected.     

Palladated halloysite hybridized with photo‐polymerized hydrogel in the presence of cyclodextrin: An efficient catalytic system benefiting from nanoreactor concept

Considering the excellent performance of halloysite as a catalyst support and in an attempt to benefit from the concept of nanoreactors in the catalysis, an innovative catalytic system has been designed, in which acrylamide and bis‐acrylamide were photo‐polymerized in the presence of palladated halloysite. The novel precipitation photo‐polymerization method avoided the formation of an extended polymeric network, but led to the formation of co‐polymer on the halloysite periphery. The co‐polymer exhibited good swellability in aqueous media and formed hydrogel. This hydrophilic environment around catalytic palladated halloysite can be considered as a nanoreactor that can concentrate the substrate and bring them into the vicinity of the palladated halloysite. This catalytic system was used for promoting hydrogenation of hydrophobic nitro arenes in aqueous media. To avoid immiscibility of hydrophobic substrates and hydrophilic nature of the nanoreactor, that emerged from swelling of hydrogel, β‐cyclodextrin (CD) was utilized as phase transfer agent. The results confirmed high catalytic activity of this catalytic system. Even highly hydrophobic substrates could tolerate hydrogenation under this protocol to furnish the corresponding product in high yield. Finally, the contribution of both CD and hydrogel to the catalysis was confirmed. Moreover, studying the recyclability of the catalyst as well as Pd leaching proved the high recyclability of the catalyst and low leaching of Pd nanoparticles.     

Two Colour Photoflow Chemistry for Macromolecular Design

We report a photochemical flow setup that exploits λ‐orthogonal reactions using two different colours of light (λ₁=350 nm and λ₂=410 nm) in sequential on‐line irradiation steps. Critically, both photochemically reactive units (a visible‐light reactive chalcone and a UV‐activated photo‐caged diene) are present in the reaction mixture. We demonstrate the power of two colour photoflow by the wavelength‐selective end group modification of photo‐caged polymer end groups and the subsequent polymer ring closure driven by a [2+2] cycloaddition. Importantly, we evidence that the high energy gate does not induce the visible light reaction of the chalcone, which attests the true λ‐orthogonal nature of the flow reaction system. For the first time, this study opens the realm of photoflow reactions to λ‐orthogonal photochemistry.     

Novel transparent poly(silazane) derived solvent-resistant, bio-compatible microchannels and substrates: application in microsystem technology

In this report we have described fabrication of preceramic polymer-derived transparent, solvent-resistant, thermally stable and bio-compatible microchannels and substrates using soft-lithography methods such as micromolding in capillary (MIMIC) and micromolding. The micromolding technique was preferred in the current work to fabricate channels by thermal and photo crosslinking of a commercially available poly(vinyl silazane) (VL 20, KION Corporation, USA). Both thermal and photo cured preceramic polymer channels were found to possess unique glass-like characteristics, such as transparency and chemical inertness. However, their surfaces were identified to be hydrophobic with a contact angle of 101 degrees . To have an insight on the nature of the surface groups present on the surface of the cured preceramic polymer, ATR-IR was carried out. The hydrophobic nature of the cured polymer was best utilized for direct patterning of protein by nonspecific binding.     

Facile Fabrication of Concentrated Polymer Brushes with Complex Patterning by Photocontrolled Organocatalyzed Living Radical Polymerization

Photocontrolled surface‐initiated reversible complexation mediated polymerization (photo‐SI‐RCMP) was successfully applied to fabricate concentrated polymer brushes with complex patterning structures. Positive‐type patterned polymer brushes were obtained by photo‐SI‐RCMP under visible light (550(±50) nm) using photomasks. A particularly interesting finding was that negative‐type patterned polymer brushes were also obtainable in a facile manner. A nonspecial UV light (250–385 nm) enabled the preparation of pre‐patterned initiator surfaces in a remarkably short time (1 min), leading to negative‐type patterned polymer brushes. Based on this unique selectivity between visible and UV light, the combination of two patterning techniques enabled the preparation of complex patterned brushes, including diblock copolymers, binary polymers, and functional binary polymers, without multistep immobilization of one or more initiators on the surfaces.     

Dye doped polymer films: From supramolecular photochemistry to the molecular computer

A new concept of “molecular computing” based on spectral hole-burning, the interaction of molecular energy levels with an externally applied electric field and the interferometric properties of holography is presented. The molecular processor introduced here relies on the spectroscopic properties of a dye doped polymer film, which simultaneously can be used for image recording and for parallel processing of the stored information.     

KINETICS OF DYNAMIC HOLOGRAM RECORDING IN POLYMER FILMS WITH IMMOBILIZED BACTERIORHODOPSIN

Abstract
Polymer films with immobilized photosensitive membrane protein, bacteriorhodopsin (BR), were prepared and investigated. A sensitive holographic interferometer with phase modulated optical beams was used for investigation of kinetics of dynamic hologram recording in BR polymer films. It was found that phase hologram formation consisted of two quasi-exponential stages demonstrating existence of a diffusive process in obtained films. It was shown that the kinetics of a phase hologram recording by high intensity beams do not correlate with the exponential law. The applicability of BR polymer films as reversible photorefractive materials for dynamic holography and real-time interferometry was discussed.