含手性末端基偶氮聚合物膜的全息光栅研究

偶氮苯侧链型高分子由于其含有偶氮苯基团 ,在光作用下会发生可逆的顺反异构过程 ,具有光致取向特性 ,在光学处理、衍射光学、投影显示、光开关等许多方面具有潜在的应用性[1] .近 1 0多年来国内外学者对此类化合物进行了广泛的研究 ,已有文献报道可利用Ａｒ+激光束在偶氮苯聚合物薄膜上直接“写入”表面凸起光栅 ,并且通过原子力显微镜观测到光栅起伏 .这种光栅很稳定 ,并可以利用光学方法“擦去” .偶氮苯聚合物上述独有的性质引起了许多学者的兴趣[2 ,3] .另一方面 ,由于旋光性聚合物在光学物理性质上的优势 ,我们已将手性基团引入偶氮苯…     

偶氮苯取代吡唑啉衍生物的制备及其电子光谱研究

含有多个生色团化合物的内部较易实现分子内的能量传递、电子转移或电荷分离 ,因此 ,设计制备具有新颖结构的多功能化合物不仅在分子电子学和分子光子学等领域备受关注 ,同时也是模拟研究生物体内生命过程的重要内容 .由于吡唑啉具有较高的荧光量子产率和较好的空穴传输特性 ,在电致发光器件中已有广泛的研究 [1～ 3] ,同时偶氮苯类化合物的光致顺反异构化性质及其在异构化过程中伴随的结构、偶极矩及光学性质的改变 ,使其在光学信息存储、光化学开关和非线性光学等领域中具有极其广阔的应用前景 [4～ 7] .本文设计合成了通过柔性链将偶氮苯…     

含偶氮苯光学活性侧基聚合物研究进展

综述了含偶氮苯光学活性侧基聚合物近年来的发展概况 ,介绍了多种聚合体系的类型。由于偶氮苯光于活性侧基的存在 ,使得这些聚合物具有光致变色性、非线性光学活性、光学各向异性等光学性能 ,在光信息存储材料、非线性光学材料、液晶材料、光电子器件、生物分子活性光调控、纳米技术等诸多领域都有广泛的应用。     

偶氮苯取代吡唑啉衍生物PMMA薄膜的光诱导双折射性质研究

芳香族偶氮化合物的顺反异构化反应长期以来一直受到人们的关注 [1,2 ] .当把偶氮生色团引入到聚合物中时 ,在线性偏振光的激发下 ,偶氮生色团能发生“反 -顺 -反”光异构化循环 ,并且偶氮发色团会沿着偏振光偏振方向的法线重新取向 ,从而导致光致双折射现象的发生 [3 ] .因此 ,这类聚合物在光学存储 [4 ] 、光学开关和全息光栅 [5] 等方面具有重要的应用价值 .为研究偶氮苯的结构对光诱导双折射性质的影响 ,本文制备了偶氮苯取代的三苯基吡唑啉衍生物 ,并把其掺杂入 PMMA中 ,研究了薄膜的偏振光诱导光致双折射性质 ,讨论了温度对其光致双…     

偶氮液晶在光学材料中的应用进展

偶氮液晶是一类分子中含有偶氮苯结构的液晶,其偶氮基团在光照射下,能发生可逆的顺反异构反应。由于偶氮苯的顺式结构不能形成稳定的液晶相,因此,偶氮液晶在具有向列液晶温敏性质的同时,也具有特有的光敏性质,其相变与分子取向能够通过光照进行控制。这种特性使得偶氮液晶在光学功能材料方面具有广泛的应用。本文介绍了偶氮液晶的基本特性,结合作者自身的研究工作阐述了其在光学材料应用方面的研究进展。     

光学活性偶氮苯自组装膜的制备及其蛋白吸附行为

研究了在紫外光作用下, 牛血清白蛋白(BSA)在偶氮苯自组装膜上光控可逆的吸附行为. 首先合成羧基偶氮苯衍生物, 并在金膜表面制备偶氮苯自组装膜, 采用紫外吸收光谱(UV)、原子力显微镜(AFM)观察偶氮苯衍生物的光学顺反异构现象以及偶氮苯自组装膜表面形貌的变化. 同时利用等离子体表面谐振仪(SPR)考察偶氮苯光学异构对牛血清白蛋白(BSA)在自组装膜表面上的吸附行为的影响. 结果表明, BSA在偶氮苯自组装膜表面的吸附作用主要来自于BSA分子与自组装膜之间的静电作用及亲疏水作用. 在紫外光作用下, 偶氮苯自组装膜可以实现光控可逆的牛血清白蛋白分子吸附行为.     

一维链状铜配位聚合物[Cu(bpb)(PPh_3)_2]_n·nClO_4·nCH_2Cl_2·nH_2O的合成、晶体结构与荧光性质研究

<正>因配位聚合物具有丰富的微观空间拓扑结构和优异独特的宏观特性,在催化、光学、材料、信息存储等领域具有广泛的潜在应用前景[1-2]。联吡啶配体及其衍生物是一类具有特殊性质的配体,其多齿的配位点和对大多数金属离子具有较强亲和力的     

甲氧基苯基偶氮衍生物电子结构与二阶NLO性质的HF/FF方法研究

采用量子化学HF方法在6-31G水平上优化6个甲氧基苯基偶氮衍生物分子的几何构型，利用HF／6-31G。方法计算它们的偶极矩、电荷分布、前线分子轨道能级并结合有限场(FF)方法计算二阶非线性光学系数．结果表明，偶氮苯衍生物分子具有很好的共轭性，在给吸电子基团作用下，电荷转移明显，展现示出较强的极性．偶氮苯衍生物分子与苯乙烯、Schiff碱类衍生物相似，也具有很好二阶非线性光学活性，同时六元杂环取代的偶氮苯衍生物分子二阶非线性光学系数比未取代的大，五元杂环取代结果相反．     

偶氮苯作用的核酸开关在生物体内的可逆光调控

随着人们对偶氮苯分子光异构化机理和特性认识的深入,偶氮苯在核酸分子中的引入及其相关过程的可逆调控也受到了大量关注.偶氮苯分子作为光响应元件不仅用于合成智能材料或分子机器,而且正迅速渗透到化学生物学体系的分析和调控.考虑到核酸分子包含的信息多样性,小分子偶氮化合物引入到核酸分子中,可实现开关核酸的结构、RNA沉默、基因表达、适配体识别、酶活性等,也可用作核酸探针了解结构信息和分子之间的作用机理.因而,功能核酸的光可逆调控及其在生物领域中的应用,成为核酸化学领域的热门课题.本文主要阐述了偶氮苯与核酸结合的4种不同方式的设计原理及特点,通过筛选一些有代表性的例子,介绍偶氮苯类光敏分子的光异构化性能及其对核酸结构和功能的可逆调控在生物领域的研究进展,并列举出现阶段可能存在的问题,及对未来的发展前景进行展望.     

偶氮苯超分子聚合物有序多孔膜的制备与定向光调控

两亲性嵌段共聚物聚苯乙烯-b-聚(4-乙烯基吡啶)(PS-b-P4VP)中,吡啶的氮原子能够与4'-碘-4-二甲氨基偶氮苯(IAzo)的碘原子以卤键结合,从而构筑超分子聚合物.通过静态呼吸图法制备了含偶氮苯的PS-b-P4VP超分子聚合物PS-b-P4VP(IAzo)x蜂窝状有序多孔膜,并详细研究了IAzo的含量及光照条件对孔尺寸和形貌的影响.通过红外光谱、扫描电镜等表征手段对PS-b-P4VP(IAzo)x的制备及成膜的表面和断面形貌进行了研究.结果表明,随IAzo含量的增加,超分子聚合物多孔膜的孔径逐渐增大.此外,由于偶氮苯的光致形变特性,在线性偏振光照射下,多孔膜的圆孔可以转变为矩形孔或菱形孔.增加偶氮苯含量,能够加快形变速度.提出了简单新颖的光响应超分子聚合物制备方法,并成功地实现了孔结构的光调控,为可控表面图案的设计和应用提供了新的解决思路.     

聚合物Langmuir—Blodgett膜研究进展

聚合物LB膜可用两种方法制备,一种是两亲单体成膜再进行聚合反应,另一种为直接从两亲聚合物在亚相表面铺展成膜并转移。本文综合聚合物LB膜的研究状况,包括两亲聚合物和非两亲聚合物,对聚合物LB膜的成膜特点,结构和性能作了描述,并简要介绍了聚合物LB膜的应用前景。     

Synthesis and Investigation of Monoesters of Polymaleic Acids with Azo Group

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Photo‐optical properties of polymer composites based on stretched porous polyethylene filled with photoactive cholesteric liquid crystal

A new type of polymer–liquid crystal composite with photovariable dichroism and birefringence is described. Porous stretched polyethylene films were used as polymer matrices. To induce a cholesteric phase in a commercial nematic host, a chiral photochromic dopant based on sorbide and cinnamic acid capable of E–Z isomerization under UV irradiation was used. A merocianine‐type substance was selected as a dichroic dye. Introduction of a dye‐doped cholesteric mixture with a helical pitch higher than ～300 nm to polymer film led to an almost complete transition from a cholesteric to an oriented nematic phase, as well as to an increase in birefringence and the appearance of dichroism. Decrease of the helical pitch by increasing in the chiral dopant concentration in the liquid crystal–polymer composite results in a reduction of the dichroism values. UV irradiation of polymer composite leading to an isomerization of the chiral dopant and helix untwisting induces a noticeable gradual growth of dichroism and birefringence. These new composites can be considered as promising materials for optical applications.     

高分子LB膜

概述了高分子Langmuir-Blogett膜,并依其成膜方式分别介绍了可聚合LB膜、聚合物的LB膜及其它几种LB膜。     

Photo-optical properties of polymer composites based on stretched porous polyethylene filled with photoactive cholesteric liquid crystal

A new type of polymer-liquid crystal composite with photovariable dichroism and birefringence is described. Porous stretched polyethylene films were used as polymer matrices. To induce a cholesteric phase in a commercial nematic host, a chiral photochromic dopant based on sorbide and cinnamic acid capable of E-Z isomerization under UV irradiation was used. A merocianine-type substance was selected as a dichroic dye. Introduction of a dye-doped cholesteric mixture with a helical pitch higher than ∼300 nm to polymer film led to an almost complete transition from a cholesteric to an oriented nematic phase, as well as to an increase in birefringence and the appearance of dichroism. Decrease of the helical pitch by increasing in the chiral dopant concentration in the liquid crystal-polymer composite results in a reduction of the dichroism values. UV irradiation of polymer composite leading to an isomerization of the chiral dopant and helix untwisting induces a noticeable gradual growth of dichroism and birefringence. These new composites can be considered as promising materials for optical applications.     

Orientational phenomena in comb-shaped liquid crystal polymers induced by laser beam irradiation

Action of the laser illumination on optical properties of liquid crystalline (LC) comb-shaped acrylic and methacrylic copolymers containing cyanobiphenyl mesogenic groups and azo dye fragments has been studied. Under an illumination the cis-trans configurational changes of dye fragments take place and reorientation of the side groups towards a direction perpendicular to the electric vector of the actinic light occurs. As a result the photoinduced optical birefringence (δn = 0.05-0.11) appears. The detailed study of dichrotic and optical properties of polymeric films, kinetics and relaxation of δn, as well as mechanism of orientational transformations during a laser illumination are discussed. The induced optical anisotropy of the films can be changed reversibly by rotating the electric vector of the laser beam in respect to the film that may be used in reversible optical data storage.     

Photochemical reaction, acidichromism, and supramolecular nanoarchitectures in the Langmuir-Blodgett films of an amphiphilic styrylquinoxaline derivative

An amphiphilic styrylquinoxaline derivative, 3-(4-(hexadecyloxy)styryl)quinoxalin-2(1H)-one (SQC16), was newly synthesized to investigate their photochemical and gas responsive properties in organized molecular films. It was observed that SQC16 can spread as a monolayer on the subphases with various pH values and be subsequently transferred onto solid substrates. While SQC16 showed predominantly reversible trans-cis photoisomerization in methanol solution, it showed both photoisomerization and photodimerization in Langmuir-Blodgett (LB) films. Photodimerization was only observed in the LB film due to the face-to-face arrangement of the functional headgroup in the LB film, and the process was irreversible. In addition, the LB film showed acidichromism, i.e., when the film was exposed to HCl gas its color changed from yellow to red, and the color could be recovered after exposure to NH(3) gas. The process was reversible and could be repeated many times. An interesting surface morphology of the SQC16 LB film was revealed. It was observed that SQC16 can form nanowire architecture in the transferred one-layer LB film. This morphology can be changed upon photoirradiation or in gas reactions. Through the atomic force microscopy measurements it was suggested that the photodimerization predominantly occurred from the nanowire structures, while during the acidichromism the reaction occurred preferentially in the flat region. X-ray diffraction studies revealed that while layer distance showed a slight change for the LB film during acidichromism and photoreaction, the layer structure of SQC16 LB film was retained.     

Photomodulation of the chiroptical properties of new chiral methacrylic polymers with side chain azobenzene moieties

We have investigated the photoinduced optical properties of a new class of chiral methacrylic polymers characterised by the presence in the side chain of an optically active pyrrolidinyl ring linked to a trans-azoaromatic system. The homopolymers are enantiomerically pure and their strong optical activity indicates that the macromolecules assume, both in solution and in solid thin films, highly homogeneous conformations with a prevailing chirality. As expected, the studied polymers exhibit reversible linear dichroism and birefringence when irradiated with linearly polarised light. By irradiating with circularly polarised light, we have discovered that it is possible to photomodulate the chiroptical properties of the polymer films. After irradiation with L-polarised light, the CD spectra of the films show a net inversion of their relative sign. The effect is reversible and the original shape of the CD spectra can be restored by pumping with R-polarised radiation. This unexpected new phenomenon can be explained in terms of the ability of the L-polarised radiation to invert the prevailing helicity of the polymeric chains. The observed effect seems to open new possibilities for the use of azobenzene-containing materials as chiroptical switches.     

Synthesis of novel hybrid films of a layered silicate and alkylammonium cations on rough polymeric surfaces by Langmuir–Blodgett method

Hybrid films of a layered silicate and an amphiphilic alkylammonium (hexadecyltrimethylammonium) cation have been prepared by Langmuir–Blodgett (LB) method and transferred onto a polyamide surface by dip coating. This is the first time that stable LB hybrid monolayer and multilayer films have been formed on rough polymeric surfaces. The films were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and water contact angle measurements. XRD and FTIR showed that the hybrid multilayer was well-organized and the thickness of one layer was calculated to be 1.6 nm. Furthermore, the layered silicate was determined to be on the substrate side and the amphiphilic molecule layer was exposed to the air side. This provides a novel methodology for the surface modification of polymers.     

Formation of ordered mesoporous films from in situ structure inversion of azo polymer colloidal arrays

This work shows that mesoporous polymeric films with spherical and elliptical pores can be obtained by in situ structure inversion of the azo polymer colloid arrays through selective interaction with solvent. The epoxy-based azo polymer contained both the pseudo-stilbene-type azo chromophores and the hydrophilic carboxyl groups. The colloidal spheres of the azo polymer were prepared by gradual hydrophobic aggregation of the polymeric chains in THF-H2O media, induced by a steady increase in the water content. Ordered 2D arrays of the hexagonally close-packed colloidal spheres were obtained by the vertical deposition method. After the solvent (THF) annealing, the ordered 2D arrays were directly transformed to mesoporous films through the sphere-pore inversion. Under the same condition, the 2D arrays composed of the ellipsoidal colloids, which were obtained by the irradiation of a polarized Ar+ laser beam on the colloidal sphere arrays, could be transformed to films with ordered elliptical pores. To our knowledge, this is the first example to demonstrate that mesoporous structures can be directly formed from the colloidal arrays of a homopolymer through structure inversion. This observation can shed new light on the nature of self-assembly processes and provide a feasible approach to fabricate mesoporous structures without the infiltration-removal step. By exploring the photoresponsive properties of the materials, mesoporous film with special pore structure and properties can be expected.