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采用退偏振光强度法、SALS和POM测定了高分子液晶态有序微区结构随体系温度变化的规律,并用DSC法研究具有不同有序微区结构尺寸的液晶态的结晶过程。结果发现,高分子液晶态有序性或有序微区结构是随着体系退火温度和时间的变化而变化。同时从相应的不同有序性为起始态进行结晶时,其结晶速率明显不同,并讨论了高分子液晶态的结晶机理。 相似文献
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Finkelmann和等人对侧链胆甾型高分子液晶的研究表明,将具有液晶功能的低分子基团,经过一个软段连接到柔性高分子主链上的梳型高分子在一定的温度下可以形成液晶态,调节侧链高分子液晶的分子结构、软段长度,可以改变其相态转变温度及微区形态。前已报导具有不同侧链结构的聚甲基丙烯酸胆甾醇酯共聚物的合成、相态转变及光学性质,本文通过对聚甲基丙烯酸胆甾醇乙烯酯共聚物(PMACE)的液晶态及结晶态的微细结构及相态转变与胆甾侧链含量关系的研究,给出了液晶态的形成条件及结构特征。 相似文献
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分子链构象变化对高分子液晶相行为的影响 总被引:4,自引:0,他引:4
聚肽高分子溶解在含有机酸的有机溶剂中可以在室温条件下形成液晶.随着温度的下降,体系中的酸分子会引起聚肽分子链发生由刚性螺旋结构向柔性无规线团结构的构象转变.这种转变将导致一个由液晶态向非液晶态的相变.在Flory格子理论和Zimm Bragg理论的基础上,作者已提出了有关这一现象的理论解释,并通过引入一个与温度有关的库恩链长径比xk,使理论进一步完善,更切实际地解释聚肽液晶的相行为.此外,还讨论了不同分子刚柔性,不同高分子 溶剂作用系数χ对液晶相行为的影响,以及研究了聚肽液晶的有序参数. 相似文献
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一系列含T-型二维液晶基元的液晶高分子配体的合成 总被引:2,自引:0,他引:2
以4,4′ (α,ω 亚烷基二酰氧)二苯甲酰氯和2,4 二羟基 4′ 烷氧基偶氮苯为单体,通过溶液聚合,合成了一系列新的含T 型二维液晶基元的液晶高分子配体.单体的结构通过元素分析、IR、1H NMR和MS等方法确证.高分子配体通过GPC、DSC、TG、WAXD和偏光显微镜等方法测试表征,发现所有的高分子配体加热至各自的熔点以上都能形成液晶态,在液晶态可以观察到向列型的丝状织构和纹影织构.它们的熔点(Tm)和液晶态的清亮点(Ti)随分子中末端烷氧基增大和柔性间隔段长度增加呈规律性变化.特别值得一提的是,发现末端不含取代基的高分子配体也能产生液晶态,这对该类高分子液晶态生成的机制与液晶态的织构提供了一个新的研究课题[1]. 相似文献
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本文用界面缩聚法合成聚对氧化偶氧苯酚酯系列热致性液晶高分子。并用DSC,X-光衍射和偏光显微镜对其结构和液晶相进行了表征与研究。观察液晶态织态结构,计算液晶态时分子链间距,并观察聚合物取向液晶态的结晶结构。 相似文献
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近晶C(Sc)相串型液晶高分子的合成与表征 总被引:1,自引:0,他引:1
以2,5 二(对烷氧基苯甲酰氧基) 对苯二酚和不同结构的脂族二酰氯为单体,采用低温溶液缩聚的方法,合成了一系列新的液晶基元垂直于分子主链的Sc相串型液晶高分子.单体的结构通过元素分析、IR、1H NMR和MS等方法确证.聚合物通过GPC、DSC、TG、WAXD和偏光显微镜等方法测试表征.研究发现,所有的聚合物加热至各自的熔点以上都能形成液晶态,在液晶态可以观察到纹影或焦锥织构.通过变温X 射线衍射证明它们为Sc相.所有聚合物的熔点(Tm)和液晶态的清亮点(T1)随分子中末端烷氧基增大和柔性间隔段长度增加逐渐降低,液晶态温度范围变窄. 相似文献
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热致型光敏液晶高分子在液晶场中光交联反应的研究 总被引:1,自引:0,他引:1
研究了具有肉桂酸酯侧链基的热致型液晶高分子的光交联行为.结果表明,在20min紫外光照射的条件下,形成液晶相的液晶高分子膜的光交联凝胶百分率要明显高于尚未形成液晶相的同种高分子膜.对形成液晶相的高分子膜,在环境温度低于液晶各向同性温度T时,温度对光交联凝胶百分率的影响甚微.这表明,由于液晶高分子中致介单元的聚集和有序排列形成的微区结构也影响了大分子链侧基肉桂酸酯的聚集状态.从而使其光化学性质发生变化. 相似文献
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本文用热台偏光显微镜和透射电子显微镜研究了聚对苯甲酰胺(PBA)/H_2SO_4液晶态生长球晶的形态结构和结晶机理。结果表明,PBA/H_2SO_4向列型液晶相具有过冷状态,可达30—40℃左右,并可生长球晶结构,一般直径可达5毫米左右。20Wt%溶液在不同的过冷态结晶时,可以生成三种形态的球晶结构,这是由于构成球晶的基本结构单元——有序微区结构在不同过冷条件下堆砌排列的规整程度不同的缘故。球晶的形态结构只与过冷程度有关,而与溶液的浓度无关。同时还研究了变温和剪切应力下结晶的球晶形态。 相似文献
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采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子.聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性.随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。 相似文献
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Michael A. Yandrasits Jianhua Chen Fred E. Arnold Stephen Z. D. Cheng Virgil Percec 《先进技术聚合物》1994,5(12):775-784
A series of thermotropic polyethers synthesized from 1-(4-hydroxyphenyl) - 2 - (2 - methyl - 4 - hydroxyphenyl) - ethane and α,ω-dibromo-n-alkanes with odd numbers of methylene units (MBPE-n = odd) shows monotropic mesophase behavior. In isothermal differential scanning calorimetry (DSC) experiments, two—sometimes even three—exothermic transition processes can be observed when the crystallization temperature is below the mesophase transition temperature, while only one exothermic process is present above the mesophase transition temperature. The melting behavior of the crystals grown from the mesophase and from the isotropic melt states is different. The crystals grown from the mesophase state exhibit a larger overall heat of transition and a higher transition temperature compared with those grown from the isotropic melt. This may be attributed to the molecular interfacial connections between the crystal and amorphous regions when MBPEs crystallize from the mesophase state. The difference in morphology between the crystals grown from the different states has also been studied with polarized light microscopy (PLM) and transmission electronic microscopy (TEM). The structures of the crystals grown from the different states are, however, the same, as evidenced through wide-angle X-ray diffraction (WAXD) measurements. From the banded morphology of MBPE samples observed from PLM, the defect textures observed through TEM and the results of WAXD experiments, this mesophase can be identified as a nematic liquid crystal state. 相似文献
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Bao-jing Luo Hong-fei Li Wen-yang Zhang Cheng-bo Zhou Jing-qing Li Cong-hua Lu Xue-hao He 《高分子科学》2017,35(5)
The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5(iPP/TMB-5) were investigated by synchrotron radiation wide angel X-ray diffraction(SR-WAXD), differential scanning calorimeter(DSC) and polarized light microscope(PLM). It was found that α-crystallization lagged behind β-crystallization at normal temperatures, but the discrepancy reduced with increasing temperature. TMB-5 could not induce β-iPP when the nucleation agent is wrapped up with α-crystal that crystallized at high temperatures. The polymorphic composition of iPP/TMB-5 was susceptible to the introductory moment of shear. New crystallization process of β-nucleated iPP was proposed to understand the experimental phenomena which could not be explained by those reported in the literature. It was supposed that polymer crystallization initiated from mesophase, and the formations of iPP crystals involved the organization of helical conformation ordering within mesophase. It was proposed that the iPP melt contained mesophases with stereocomplex-type ordering of right-handed and left-handed helical chains which could be disturbed by shear or TMB-5, leading to different polymorphic structures. 相似文献
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The domain microstructure and the nematic LC mesophase in a series of side-chain liquid crystalline/isotropic (LC/I) diblock copolymers with systematically varied block volume fractions were studied in a broad temperature range (25–170 °C) by DSC, polarized microscopy, and wide and small angle X-ray scattering. At all temperatures the block copolymers are microphase separated. The PSLC block copolymers exhibit order at two length-scales: on one hand, a nematic LC mesophase with characteristic length-scale of 0.43 nm (intermesogen distance); on the other hand, lamellar, hexagonal or cubic domain microstructures with characteristic length-scales of 27–44 nm (lattice parameter). The LC block was either located in the matrix or confined inside the microdomains. The thermotropic behavior is characterized by the sequence g/~35 °C/n/~115 °C/i and is not affected by the domain microstructure and/or dimensions. Analysis of the lamellar dimensions showed that the LC chain is stretched. With increasing temperature, a thermal expansion of both blocks takes place followed by a retraction of the LC chain above TNI. The phase diagram is asymmetric and does not alter above TNI. No order-to-order transitions triggered by the nematic-isotropic transition are observed. It was shown that domain microstructures of low interfacial curvature (lamellar and hexagonal) are energetically favored over the geometrically expected ones of high interfacial curvature (micellar cubic) due to the presence of nematic LC mesophase in the matrix or in the microdomains. By comparison to theory a Kuhn segment length of the LC block bLC=0.86 nm was derived from the location of the lamellar/hexagonal phase boundaries.This paper is dedicated to Prof. Fischer on the occasion of his 75th birthday. 相似文献