芳香共聚酯B-N多种向列织构的形态研究

 从一种聚芳酯B-N得到了丝状(包括细丝和粗丝)、纹影状和大理石纹状等与小分子向列液晶相似的多种织构。由于样品淬火后晶片装饰在织构上而不影响分子取向矢的分布,因而可以用化学刻蚀和电镜技术揭示其向错和取向矢图。电镜和光学显微镜的结果相互补充,表明了细丝和粗丝状织构的分子取向矢分布很不相同,是两种不同的织构,而粗化始于第二熔融降温。在这些向列织构中分别发现了S=±(1/2)和s=+1的向错的例子和平面内微区转向壁的证据。     

高分子液晶向列相的向错结构

高分子液晶态向错结构在正交偏振片下呈现出具有不同数目黑刷子的纹影织构，是由于分子指向矢取向排列上的不连续性所引起的一种光学效应。近年来，高分子液晶态向错结构的研究已取得了较大进展，发展和应用片晶装饰、条带织构装饰和表面裂纹装饰等技术可以在电镜和偏光显微镜下直接观察各种向错结构。本文简要介绍高分子液晶态向列相的向错和反转壁结构的几何学、高强度向错以及近年在实验上观察各类型向错形态的研究进展。     

条带织构装饰技术观察含T─型液晶基元的热致性聚芳酯液晶态的向错

采用条带织构装饰新技术研究了含Ｔ─型液晶基元的热致性聚芳酯液晶态的向错形态．经过培养的液晶样品无需剪切，淬火后便可呈现出围绕向错点取向排列的条带织构，而条带织构长轴的垂直方向正代表了液晶基元的指向矢方向，这样，在普通偏光显微镜下就能直接观察到这些条带织构装饰的强度Ｓ＝±１／２和Ｓ＝±１的向错，并观察到Ｓ＝－３／２的高强度向错和闭环状的反转壁．     

条带织构装饰技术观察含T─型液晶基元的热致性聚芳酯液晶态的向错

采用条带织构装饰新技术研究了含Ｔ─型液晶基元的热致性聚芳酯液晶态的向错形态．经过培养的液晶样品无需剪切，淬火后便可呈现出围绕向错点取向排列的条带织构，而条带织构长轴的垂直方向正代表了液晶基元的指向矢方向，这样，在普通偏光显微镜下就能直接观察到这些条带织构装饰的强度Ｓ＝±１／２和Ｓ＝±１的向错，并观察到Ｓ＝－３／２的高强度向错和闭环状的反转壁．     

主链型高分子液晶向列相向错观察的进展

综述了主链型高分子液晶向列相向错在实验观察方面的进展。从纹影织构的观察和展曲、弯曲弹性常数相等条件下的二维曲率弹性理论出发探讨了向错结构的几何特征。简要涉及了弹性常数不相等对向错的影响、向错核心的本质和反转墙的观察;给出了拓扑强度s高达4的高阶向错的实验观察结果;归纳出描绘向错周围指向矢场的主要实验方法:1)片晶装饰;2)条带织构装饰;3)表面微裂纹装饰。本文对上述方法进行了讨论和比较,列举了一些电子显微镜和光学显微镜照像的图例。     

用马赛克形貌装饰法研究碗形分子柱状向列相的向错和分子指向矢分布

选用香兰素为原料,采用传统的三聚成环法,合成了两种碗形CTV系衍生物——CTV-1和CTV-2,前者的外围基团是—OCH3和—OCH2CH3,后者的外围基团是—OCH3和—OCH2COOCH3.两种碗形CTV分子均是热致液晶,呈现向列相典型的粒状织构和单微区的均匀织构,还观察到规则美观的马赛克形貌,每块矩形马赛克的尺寸为数十微米数量级,多次升降温循环能重复出现和消失.发现马赛克形貌实质上是在冻结的向列相织构上结晶化并收缩龟裂而装饰出来的光学图案.通过扫描电镜的研究,观察到马赛克形貌是由片晶组装而成的,每块马赛克就是一块矩形的多层片晶,多层片晶由单层片晶堆积而成.直接观察到片晶的组成单元是直径约1微米的微纤,而微纤应当是束状的碗形分子柱.马赛克形貌装饰在碗形分子柱状向列相上,通过这种新方法观察到s=＋1（δ=0和δ=90°）和s=±1/2多种点向错和Nèel微区壁等周围的分子指向矢分布情况.说明碗形分子柱状向列相与一般向列相有类似的液晶行为,但取向的基本结构单元是碗形分子柱,或者由碗形分子柱组成的束（即微纤）,而不是碗形分子本身.碗形分子柱起了一般向列相中棒状分子的作用,所以本文以一个新名称＂碗形分子柱状向列相＂BCN（Bowlic Columnar Nematic）来表示这种不同常规的向列相.     

用条带织构装饰技术研究液晶全芳共聚酯的取向和非取向膜

用退火使条带织构装饰在全芳共聚酯的取向膜上，在偏光显微镜下同时观察到微纤和条带。微纤分三个层次，即直径分别为数十微米的微纤束、数微米的微纤和０．３微米的亚微纤，退火后三个层次的微纤松弛成不同的形态，微纤束仍笔直沿剪切方向取向，微纤松弛成螺旋形，而亚微纤松弛成波浪形从而观察到条带织构：微纤直径越小越易松弛，另一方面，非取向态织构退火后由亚微纤形成的条带装饰结果直观地揭示了微区内外分子指向矢的分布和它们在边界上的变化。退火时条带织构的形成被解释为分子的弹性回缩力缓慢发生作用使分子松弛所致。     

热致液晶含氯侧基聚芳醚酮的单晶状条带织构

通常主链液晶高分子在受到剪切作用时 ,分子微纤呈周期性锯齿状排列 ,其光学效应表现为在偏光显微镜下可观察到相互平行且与剪切方向垂直的条带织构 [1] .而厚度适中的主链液晶聚合物薄膜经过热处理 ,即使没有受到剪切取向的作用 ,介晶微区的尺寸发展到一定大小时也会形成条带织构 ,即所谓结晶诱导[2 ] 和固化诱导 [3,4 ] 的条带织构 .在所报道的条带织构中 (包括剪切和非剪切 ) ,分子链均平行于膜平面 .本文研究发现 ,热致液晶氯代聚芳醚酮的薄膜样品在其高有序液晶温区经热处理 ,可形成结晶诱导的单晶状条带织构 ,其分子链垂直于膜平面 .…     

软体动物平滑肌保留收缩机制

本文研究了河蚌(Cristaria plicata,Leach)闭壳肌的平滑部分籍乙酰胆碱引起的保留性收缩现象,在电子显微镜下观察了在固定的超薄切片中粗细丝的排列和在游离的粗丝中结构的细节.粗丝呈现大角度的转折,有时几根粗丝互相缠绕.细丝排列不规则,一根细丝可同许多根粗丝相联结.当此平滑肌恢复到松弛状态时,粗、细丝平行排列.我们认为:粗、细丝的杂乱分布并交织成三维网格,是保留性收缩的结构基础,它使粗、细丝不易定向滑动,需要时间恢复有序的排列。     

热轧对涂层导体用镍基带立方织构形成的影响

热机械加工制备的立方织构Ni及其合金带材广泛用于YBCO涂层导体的基带。涂层导体的制备要求基带具有强的立方织构和小的晶界角。通过在冷轧前进行热轧制备了强立方织构的镍基带。用三维取向分布函数（ODF）研究了轧制织构和再结晶织构，通过扫描电镜EBSD的观测，分析了晶粒取向分布和立方织构晶界微取向角分布。结果表明，冷轧前进行热轧有利于形成很强的立方织构和小的晶界微取向角。     

Direct decoration of disclinations by solidification-induced band texture and focal-conic texture for a low molar mass liquid crystal

Two decoration methods, solidification-induced band texture decoration and focal-conic texture decoration, were established to map the director field of disclinations in a low molar mass methacrylate liquid crystal. It was found that when the specimen film is quenched from the nematic melt to room temperature, solidification-induced band texture is observed arrayed along with the schlieren texture, and the orientation of the director field can be displayed. Moreover, when the specimen is cooled from the nematic melt to 63°C and annealed, the focal-conic texture of the smectic A phase is found to grow around the corresponding disclination core with good orientation to reveal the director field. By the two decoration techniques, the director fields of disclinations with strength s = 1/2 and s = ±1 were revealed. Two types of inversion wall, loop-like wall and splay-type wall, were found by both solidification-induced band texture decoration and focal-conic texture decoration.     

Banded texture decoration of disclinations in a main chain thermotropic aromatic copolyester observed by optical microscopy

A new method for the study of texture and director patterns in a main chain thermotropic aromatic copolyester with a flexible spacer is described, whereby the molecular chain or director orientation of the nematic mesophase becomes decorated by the formation of a banded texture during quenching, without being subjected to a shear. The pattern of the decorated banded texture may be observed directly by polarizing optical microscopy, revealing the complete texture of molecular chain orientation across the whole specimen. The molecular director orientation lies perpendicular to the long axis of the bands. Various types of disclination, including an inversion wall, in the nematic mesophase of a thermotropic aromatic copolyester have been observed. This decorating technique is particularly suited for non-crystallizable main chain liquid crystalline polymers, where the lamellar decoration technique fails.     

Direct decoration of disclinations by solidification-induced band texture and focal-conic texture for a low molar mass liquid crystal

Two decoration methods, solidification-induced band texture decoration and focal-conic texture decoration, were established to map the director field of disclinations in a low molar mass methacrylate liquid crystal. It was found that when the specimen film is quenched from the nematic melt to room temperature, solidification-induced band texture is observed arrayed along with the schlieren texture, and the orientation of the director field can be displayed. Moreover, when the specimen is cooled from the nematic melt to 63°C and annealed, the focal-conic texture of the smectic A phase is found to grow around the corresponding disclination core with good orientation to reveal the director field. By the two decoration techniques, the director fields of disclinations with strength s = 1/2 and s = ± 1 were revealed. Two types of inversion wall, loop-like wall and splay-type wall, were found by both solidification-induced band texture decoration and focal-conic texture decoration.     

Direct decoration of disclinations by solidification-induced band texture for a nematic side chain liquid crystalline polymer

For a nematic polymethacrylate side chain liquid crystalline polymer, g 154 N 298 I (°C), the solidification-induced band texture has been observed aligned along the disclination under a polarizing optical microscope, when the specimen was quenched from 280°C to room temperature. The decoration technique of solidification-induced band texture, which is usually reported for main chain liquid crystalline polymers, was then introduced to reveal the director field pattern along a disclination for this side chain liquid crystalline polymer. It was found by infra-red dichroism measurements that the director orientation is parallel with the direction of the band. On this basis, disclinations with strength s=±1/2 and s=±1 were mapped according to the corresponding pattern of solidification-induced band texture. In addition, two types of inversion wall, loop-like and splay-type walls, were also found to be decorated by the solidification-induced band texture.     

片晶装饰技术研究高分子液晶向列相的向错

采用片晶装饰技术和四氧化钉染色技术相结合在透射电镜下研究了热致性高分子液晶的向错结构，在一种热致性聚芳酯的冻结液晶态中观察到了向错强度分别为Ｓ＝±１／２和Ｓ＝±１的两类共六种的向错形态，以及每个向错与其相邻向错之间相互联结和相互作用的状态．     

Disclination and molecular director studies on bowlic columnar nematic phase using mosaic-like morphology decoration method

Two bowlic cyclotriveratrylene CTV-1 and CTV-2, with different peripheral groups of —OCH₃ and —OCH₂CH₃ for CTV-1 and —OCH₃ and —OCH₂COOCH₃ for CTV-2, respectively, were synthesized by typical trimerization via a multistep sequence from vanillin. Both bowlic CTV molecules were thermotropic liquid crystals, and presented typical grainy textures of the nematic phase and homogeneous texture of the single domain nematic phase. It is of interest to observe the regular and beautiful mosaic-like morphologies after cooling from liquid crystalline phases, which appeared and vanished repeatedly in several circles of cooling and heating. The size of each mosaic was several dozens of micron. In nature, the mosaic-like morphologies are the optical pattern of cracks formed by the shrinking, due to the crystallization of frozen texture of nematic phases. By means of scanning electron microscopy, the mosaic-like morphologies were observed to consist of lamellae, and each mosaic is a rectangular multi-layer lamella, which is composed of packed single-layered lamellae. The fibrils in the diameter of about 1 μm were observed, which are the structural units of lamellae and would be the bundles of the bowlic molecular columns. The mosaic-like morphologies decorate the bowlic molecular columnar nematic phase, therefore, a novel mosaic-like morphologies decoration method was applied to reveal the director distribution of several kinds of point disclinations, such as s = +1(δ=0° and δ =90 °) and s = ±1/2, and Nèel domain walls. It was shown that the bowlic molecular columnar nematic phase behaved as normal nematic phases; however, the basic structural units ordered were the bowlic molecular column or the bundles of bowlic molecular column (i.e. fibrils), but not the bowlic molecules themselves. The bowlic molecular columns acted as the rod-like molecules in a normal nematic phase. Therefore, a new term BCN (bowlic columnar nematic phase) is used to describe the anomalous nematic phase in this paper. Supported by the National Natural Science Foundation of China (Grant No. 20774077), the Natural Science Foundation of Fujian, China (Grant Nos. E0510003 & E0710025) and the Project of Science and Technology of Xiamen, China (Grant No. 3502Z20055013)     

Director fields of disclinations in the nematic mesophase decorated by focal‐conic texture for side‐chain liquid crystalline polymers

A new decoration method termed as focal‐conic texture decoration has been established to map the director field of disclinations of nematic mesophases for a side‐chain liquid crystalline polymer (SCLCP) based on its transition from nematic to smectic phase with focal‐conic texture observed under a polarizing optical microscope. FT‐IR microscopy was used to ascertain the relationship between the mesogenic orientation direction and the orientation direction of focal‐conic texture, which exhibits consequently the director field of a disclination.