共查询到19条相似文献,搜索用时 168 毫秒
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原子力显微镜观测聚酰亚胺聚合链结构 总被引:1,自引:0,他引:1
应用LB成膜技术,将聚酰胺酸和十六胺在溶剂中混合制成单分子膜,并沉积到新解理的高取向热解石黑衬底上,然后用原子力显微镜(AFM)观测其微结构。观察到聚酰亚胺聚合链分子的在空间排列的各种构象,经定标测定:实验结构参数与用分子动力学在理论上的估算值相吻合,证明了所观测到的AFM图象的真实性。 相似文献
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研究了两亲性卟啉5,10,15,20-四-(4-十六烷基吡啶基)卟啉溴化物在气-液界面上的成膜性能,制备了其LB膜。用扫描隧道显微镜和UV-Vis光谱,荧光光谱,小角X射线衍射等实验方法研究了LB膜的形貌和卟啉大环分子在LB膜中的排列、取向和分子间的相互作用。结果表明,制备的LB膜结构均匀,性能稳定,在LB膜内,脂肪链并不是直立的,卟啉分子大环几乎平躺在基片上。 相似文献
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卟啉LB膜的分子取向,形貌和膜厚度研究 总被引:3,自引:0,他引:3
研究了5,10,15,20-四(对-山嵛酸乙酯-α-氧代苯基)卟啉分子在气液罪肌的成膜性,制备了该化合物的多层LB膜,研究了分子中不同的基团在LB膜中的取向,观测了LB膜的形貌和厚度,利用偏振UV-Vis和偏振FT-IR谱测定了分子内卟啉环和脂链取代基的取向,结果表明卟啉面法线和脂缝线与载片线间的夹角分别为37°和27°,利用TEM观测了LB膜的形貌和厚度,结果表明LB膜表面均匀,单层厚度大约为2 相似文献
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本文以LB膜技术研究了向列相液晶的取向机理。选择了四种不同金属的可溶性酞菁化合物MPc-R4作为取向材料,拉制成LB膜,诱导向列相正性液晶E-7。通过对菁酞LB膜的表征和液晶取向及电光性能的研究,认为液晶的取向是由分子间的相互作用力决定的。 相似文献
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红外透过、反射吸收光谱研究手性液晶(M1)LB膜的结构与取向 总被引:3,自引:1,他引:2
利用FTIR光谱研究了一种手性液晶化合物(M1)LB膜的结构与取向,该化合物可以形成稳定的单层与多层膜。手性分子中,芳香环平面向于垂直基片表面,分子中的烷基链部分则与基底表面法线方向成一定的角度。 相似文献
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研究了两种具有两条脂链的羟基卟啉在气液界面上的成膜性能及其LB膜。UV-Vis光谱表明,两种卟啉在LB膜中的聚集态不同,卟啉环上脂链和羟基呈对称了代时形成J-聚体,呈同侧取代时形成氢键聚集体。利用偏振UV-Vis吸收谱测定了LB膜中卟啉环的取向。结果表明,侧链和羟基的相对位置对环的取向没有影响,但影响膜中平均分子截面积的大小和环间的距离,因而影响膜中分子的聚集态。 相似文献
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利用二(3-叔丁基硅氧基)萘酞菁硅 (SiNc) Langmuir-Blodgett (LB) 膜对丝状液晶的定向进行了研究,发现在不同膜压下沉积的SiNc LB膜具有不同的定向效果.在15mN/m低膜压下沉积的LB膜上丝状液晶主要呈沿膜面水平排列,而30mN/m高膜压下沉积的LB膜则取垂直膜面取向.原子力显微镜(AFM)对相应的LB单层膜和多层膜进行的分子尺度上的形貌研究发现,高膜压条件下SiNc分子以分离的单体或聚集体形式非连续地在基片上呈线性堆积排列,形成一定的分子“纳米线”,并且大环平面垂直于基片
关键词: 相似文献
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为了提高全息聚合物分散液晶光栅的衍射效率并降低其驱动电压,改善光栅的电光特性,研究了表面平行摩擦取向对全息聚合物分散液晶光栅电光特性的影响.理论分析认为,改善相分离结构和降低液晶微滴之间的有序度差异是优化光栅电光特性的根本所在.由于进行表面取向处理后的液晶和单体之间达到扩散匹配,使得相分离的程度大幅提高,在衍射能力增强的同时驱动电压也实现了大幅下降,而且,表面取向作用也使光栅内的液晶分子均匀排列,降低了液晶微滴之间的有序度差异,从而减少了光栅的散射损失.实验结果表明:进行取向处理后的光栅其衍射效率由传统光
关键词:
全息聚合物分散液晶
衍射效率
驱动电压 相似文献
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《Physics letters. A》1999,260(5):417-423
A kind of newly synthesized polyimide (PI) LB films were fabricated to align ferroelectric liquid crystal (FLC). The topologies of PI LB films treated by different imidization processes were investigated by atomic force microscopy (AFM). It is found that the imidization temperature influences the crystalline structure of the LB films and high-temperature imidized LB films can provide the energy barrier for the realization of excellent bistability, while the ultra-thinness of LB films is helpful for the quick response of the FLC cell. 相似文献
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E. M. Aver’yanov 《Optics and Spectroscopy》2001,91(5):711-723
A study is conducted of the static shift and the splitting of the photoluminescence and electroluminescence polarized bands of uniaxial impurity molecules, embedded into uniaxial polymer films with axial or in-plane orientation of the impurity subsystem or into the vitreous phase of a nematic liquid crystal. Dependences of the band shift and the splitting on the type of alignment of impurity molecules, the polarization of transition moments in absorption and emission, and the host-impurity anisotropic interactions of different ranks are established. For both types of host matrices, characteristic features of orientational statistics of impurity molecules at a high degree of orientation ordering are studied. These features are revealed in a qualitative difference between the dependences of positions and splittings of polarized impurity fluorescence bands on the order parameter of the impurity molecules axially ordered in stretched polymer films and relevant dependences in nematic glasses. Specific features of the polarized impurity-related photoluminescence and electroluminescence in the matrices under study, observed experimentally, are interpreted. 相似文献
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The azimuthal anchoring energy of the nematic liquid
crystal 4-pentyl-4'-cyanobiphenil (5CB) on a
poly(tetrafluoroethylene) (teflon, PTFE) film is measured for
the first time. The PTFE film is deposed using the Wittmann and
Smith technique which consists on rubbing a bar of this polymer
against a glass substrate at a controlled temperature and
pressure. Measurements of the azimuthal anchoring energy are
made with a reflectometric technique which provides high
accuracy and sensitivity. The dependence of the azimuthal
anchoring energy on temperature and on the rubbing pressure is
investigated. The extrapolation length remains virtually
constant in the whole temperature range of the nematic phase
except for an increase of 25% close to the clearing temperature.
The azimuthal anchoring energy is somewhat strong and increases
with increasing the deposition pressure of PTFE. The observation
of a relevant pre-transitional anisotropy of the reflection
coefficients in the isotropic phase proves that the surface
interactions favor an excess of orientational order. Ageing of
the anchoring energy and gliding of the easy axis are
experimentally observed. Both these phenomena suggest the
presence of an anisotropic adsorbed layer of nematic molecules
on the PTFE film. 相似文献
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Daoudi A Dubois F Legrand C Laux V Buisine JM 《The European physical journal. E, Soft matter》2003,12(4):573-580
Comparative electro-optical measurements have been made on a ferroelectric liquid crystal (FLC) in surface stabilized geometry and confined to an ellipsoidal cavity within a polymer matrix. The static and dynamic electro-optical characteristics were measured for both systems and show qualitatively similar behaviours. A fast switching and important bistability were observed and characterized as a function of the applied electric field strength. The switching time between the two stable states of the surface stabilized cell was found to be longer than that found for the composite films. We argue that the faster switching dynamic of the FLC in cavities is due to the enhance of the rotational mobility of the molecules, probably (and partly) because of the soft anchoring character of the molecules at the cavity walls. Using a collective switching model in the high field regime, which assume a linear coupling between the spontaneous polarization and the local cavity electric field, we give an estimate of the rotational viscosity of the FLC molecules in the droplets.Received: 5 October 2003, Published online: 5 February 2004PACS:
61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems - 61.30.Hn Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions - 77.80.Fm Switching phenomena 相似文献
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I. Jánossy 《Pramana》2003,61(2):435-445
It is suggested that liquid crystal—polymer interfaces are coupled systems, in which the components mutually influence the
orientational state of each other. The photo-orientation process at liquid crystal-polymer interfaces provides a striking
example of such a coupling. Experiments show that the anisotropic structure generated by polarised light at a polymer surface
is strongly affected by the phase of the liquid crystal covering the polymer. Photo-orientation is significantly more efficient
when the liquid crystal is in the isotropic phase than when it exhibits orientational order. The observations are interpreted
by assuming that in the smectic and nematic phases the liquid crystal stabilises to a large extent polymer chain-segments
aligned parallel to the director, while it blocks the photo-induced formation of chain-segments in the perpendicular direction.
Other situations, in which the coupling between the liquid crystal and the polymer can be important, are also discussed briefly. 相似文献