双光轴偶氦液晶分子光致异构的机理研究

双光轴偶氮液晶（biaxial nematic azo liquid crystal）具有光致异构特性、良好的稳定性和可逆性等优点，可通过结构修饰和外部电场控制进一步提高材料性能，从而降低写入激光波长，提高稳定温度和反应速度，在高密度光学存储材料中具有极大的潜在应用价值。综述了双光轴偶氮液晶分子光致异构机理的近期研究结果，分析了它对偏振光选择吸收时发生顺反循环异构的动力学过程，展示了其实际应用。     

偶氮苯液晶聚合物的研究进展

偶氮苯类化合物由于具有独特的光致顺反异构特性,在液晶材料、光信息存储材料及非线性光学材料等许多领域都具有广泛的应用,因此近年来引起了研究者极大的关注.本文综述了近年来具有液晶性的偶氮苯类化合物的合成进展概况,对此类化合物进行了简单的分类,简要介绍和归纳了各类型化合物简单常用的制备方法,并对此类化合物的合成和研究方向作了展望.     

偶氮苯衍生物光响应机理及性能研究

偶氮苯衍生物既具有偶氮苯基团的光致顺反异构化活性,又具有优异的力学性能和加工性能,在液晶材料、光信息存储材料及非线性光学材料等许多领域都具有广泛的应用,近年来引起了研究工作者极大的关注。文章综述了偶氮苯衍生物的顺反异构机理,总结了偶氮苯衍生物在光学方面的应用及发展状况,最后提出了对其发展前景的展望。     

联萘基手性偶氮分子/液晶复合材料研究进展

基于对偶氮苯所具有的特殊的光致异构化反应机制的研究越来越深入,以偶氮苯衍生物为基础的光控材料引起广泛关注。介绍了联萘基手性偶氮分子的基本性质,综述了联萘基手性偶氮分子在胆甾相液晶反射薄膜、蓝相液晶、光诱导分子开关等方面的应用,并且对联萘基手性偶氮分子/液晶复合材料在光诱导分子开关、选择性反射等领域的发展前景进行了展望。     

含羧基的聚硅氧烷类光致变色液晶的合成及性能研究

首先通过重氮化反应合成了末端为羧基的刚性基元,再经过取代、加成、酯化反应最终合成了偶氮苯类聚硅氧烷液晶.通过UV表明其具有类似小分子的光致变性.并用POM、DSC对其液晶行为进行了表征,结果表明该化合物属于近晶A型液晶,相变区间为164.68℃～251.61℃,液晶范围较宽,有望作为光控开关和新型信息存储材料.     

侧链型偶氮聚合物液晶的光致取向

侧链型偶氮聚合物液晶是一种新型光子材料,在光信息存储和光开关等领域有重要的应用前景,近几年来,这方面的研究工作发展迅速,已成为聚合物液晶领域中新的生长点,文中对偶氮聚合物液晶光致取向各方面的研究成果进行了概要分析,对其研究进展和发展趋向进行了综述。     

偶氮液晶聚合物中基于光致双折射效应的灰阶存储

偶氮液晶聚合物中基于光致双折射效应的灰阶存储     

新型含偶氮苯生色团聚合物的制备和性能

合成了含手性碳原子的新型偶氮苯生色团,通过酰氯化反应制备出含偶氮苯生色团的单体,将所合成的单体与丙烯酸酯类单体进行自由基共聚得到以偶氮苯生色团为侧基的高分子.利用1H NMR、FTIR、UV-Vis吸收光谱,对所合成的单体及聚合物进行了结构表征.研究了所制备的聚合物的全光开关效应.结果表明,在激发光的照射下,通过聚合物中偶氮苯基团的顺-反-顺异构循环在聚合物材料中可形成光致各向异性;在较低驱动光功率(28.1 mW)下这种聚合物具有良好的全光开关效应.     

一种含偶氮苯类星型光致变色液晶材料的研究

利用紫外-可见吸收光谱,研究了一种含4个己氧基偶氮苯液晶基元的星型液晶化合物SiC6在氯仿和四氢呋喃溶液中的摩尔吸光系数、量子产率和反-顺光异构光反应,实验结果表明样品在各溶液的光致变色反应均为一级动力学反应,并求算了光致变色反应的反-顺光异构反应速率常数均为10-1数量级,远远大于偶氮类侧链液晶高分子在相同溶液中的光致变色速率常数.     

具有自发可逆形变特性的液晶弹性体

单畴结构的液晶弹性体具有自发可逆形变特性,是一种新型的智能材料,在传感器、微执行器等领域具有重要的应用价值．分别综述了热致型、光致型自发可逆形变液晶弹性体的研究发展现状,分析和阐述了单畴液晶弹性体自发可逆形变特性的原理,并展望了单畴液晶弹性体在人工肌肉和形状记忆材料方面的应用前景．     

Photorefractivity of Nematic Liquid Crystals

1.TheoryLiquidcrystalsareakindofhighlynonlinearop-ticalmedium.Thephysicsofliquidcrystalsisacom-plexbutfascinatingsubject.Inparticulartheiropti-calpropertieshavebeenthesubjectofilltensivefun-damentalandappliedinvestigationl1].Recently,ori-entationalphotorefractivityofnematicliquidcrystalshasbeenobserved[2~4].Weanalyzedthephenomenonanddevelopedatheoreticalmodelofphotorefractiv-ityinnematicliquidcrystals,andnewexperimelltalresultsareingoodagreementwiththetheory.Twocoherentlinearlypolarizedlasers…     

General Analysis of Linear Nematic Elasticity

The results of a general analysis of linear nematic elasticity on the basis of the five-parameter thermodynamic potential of de Gennes (DG) have been presented. It has been shown that, depending on the similarity of the material parameters to the conditions of marginal (limiting) stability, the DG potential describes the entire diversity of soft, semisoft, and harder behavior of weakly elastic nematic solids. It has been established that an additional soft mode of longitudinal stretching, acting along the director, can also exist alongside the known shear soft modes. A theorem on the special rotational invariance of the stress-tensor components, which is close to the principle of rotational invariance postulated earlier by Olmsted, has been proved. It has been shown that the stress tensor is symmetric if the shear modes are soft. In this case, the reduced DG potential is reduced to a one-parameter nematic potential. If the mode of longitudinal stretching is also soft, this dimensionless parameter contains no additional parameters. Simple shear and simple tension have been considered as an illustration of the theory elaborated.     

Nematic solvation of segmented polymer chains

We examine the effect of polymer chain segmentation on the recently discovered ability of nematic solvents to elongate and align polymer chain solutes. Coordinated single molecule spectroscopy and beads-on-a-chain simulations are used to study the orientational and conformational order of a series of segmented conjugated polymers, dissolved in the nematic liquid crystal 5CB. The order parameters for alignment and elongation are both observed to decrease with increasing segmentation, reflecting an interplay among conformational entropy, solvation anisotropy, and bending energy of the chain.     

Absence of Long-Wavelength Nematic Fluctuations in LiFeAs

We investigated long-wavelength nematic fluctuations in an Fe-based superconductor LiFeAs near q = (0.05, 0, 0) by measuring temperature-dependent renormalization of acoustic phonons through inelastic neutron scattering. We found that the phonons have a conventional behavior, as would be expected in the absence of electronic nematic fluctuations. This observation implies that either electron-phonon coupling is too weak to see any effect or that nematic fluctuations are not present.     

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

Smart adhesives that undergo reversible detachment in response to external stimuli enable a wide range of applications in household products, medical devices, or manufacturing. Here, a new model system for the design of smart soft adhesives that dynamically respond to their environment is presented. By exploiting the effect of dynamic soft elasticity in nematic liquid crystal elastomers (LCE), the temperature‐dependent control of adhesion to a solid glass surface is demonstrated. The adhesion strength of LCE is more than double in the nematic phase, in comparison to the isotropic phase, further increasing at higher detachment rates. The static work of adhesion, related to the interfacial energy of adhesive contact, is shown to change very little within the explored temperature range. Accordingly, the observed enhanced adhesion in the nematic phase is primarily attributable to the increased internal energy dissipation during the detachment process. This adhesion effect is correlated with the inherent bulk dynamic‐mechanical response in the nematic LCE. The reported enhanced dynamic adhesion can lead to the development of a new class of stimuli‐responsive adhesives.