【作者】 钟克利；

【导师】 金龙一；

【作者基本信息】 延边大学 ， 有机化学， 2011， 博士

【摘要】 本论文设计合成了刚棒嵌段含蒽的n型,含联苯的线型,含芘的V型三个系列的刚棒-线团液晶低聚物,研究这些分子在固态、液晶态和溶液中自组装的行为,通过改变柔性链的形状、体积、横截面积以及刚棒的形状等因素,探讨结构上微小变化对自组装结构产生的影响,从而找出分子结构或形状与自组装聚集体结构之间的内在规律。对于刚棒嵌段含蒽的n型刚棒-线团液晶低聚物,合成了四类由n型刚棒、烷基链和聚环氧乙烷链组成的n型分子,从改变刚棒中心疏水烷基链长度,改变刚棒末端烷氧基链长度,改变刚棒末端烷氧基链横截面积以及柔性链全是烷基时等四个方面对n型刚棒-线团液晶低聚物自组装结构的影响进行了研究。研究表明：(1)随着刚棒中心疏水链长度的增加,这些分子在液晶相的自组装结构从六方柱状转变到矩形柱状结构,在水中可以形成直径依次增大的纳米纤维结构；(2)改变刚棒末端烷氧基链长度,随着烷氧基链长度的增加,先形成倾斜柱状结构,然后转变成各向同性的液体；(3)改变烷氧基链的横截面积,随着横截面积的增大,分子室温下不能自组装,在水溶液中形成直径减小的棒状胶束,而且容易聚集；(4)柔性链是十八烷基的n型分子在固态形成层状结构,没有形成液晶相。对于刚棒嵌段含联苯的线型刚棒-线团液晶低聚物,合成了两类由多个联苯作为刚棒、聚环氧乙烷或聚环氧丙烷作为柔性链的线型分子,探讨了刚棒中心侧链长度对分子自组装结构产生的影响,以及刚棒中心是活性基团的自组装性质。研究表明：(1)刚棒嵌段中心引入较长的侧链将会破坏刚棒之间的π-π堆积作用力,从而使分子的自组装结构向无序化转变；(2)刚棒中心连有乙烯基的分子,在液晶相自组装后经过光照交联聚合,所得到的聚合物能保持液晶相的结构,即使温度降到室温也不再变化。对于刚棒嵌段含芘的V型刚棒-线团液晶低聚物,合成了一类以芘为刚棒中心,柔性链体积分数相同,横截面积不同的分子,探讨了刚棒形状(V型和线型)以及柔性链横截面积对分子自组装产生的影响。研究发现横截面积大的树枝链明显破坏刚棒的自组装,刚棒是线型的分子在液晶相都易形成向列相,而Ⅴ型分子则不易形成液晶相。更多还原

【Abstract】 In this thesis, three series of rod-coil liquid crystalline oligomers are synthesized, which are the n-type with anthracene in the rod block, the linear-type with biphenyl in the rod block and the v-type with pyrene in the rod block. And their self-assembly behaviors are studied at solid, liquid crystalline state as well as in solution. The effect on self-assembled structures by the minor changes in the structures of these molecules is discussed by changing such factors as the shape, the volume and the cross-sectional area of the flexible chains and the shape of the rod so as to find out the inherent laws between the molecular structure or shape and self-assembled aggregate structure.Four categories of n-shaped molecules consisting of n-typed rod blcok, alkyl chains and polyethylene oxide (PEO) chains are synthesized in the study of the n-typed rod-coil liquid crystal oligomers with anthracene in the rod block. We summarize the influence on the self-assembly structures of the n-shaped rod-coil liquid crystal oligomers by changing the length of hydrophobic alkyl chains in the center of the rod; changing the length of the alkoxyl chains at the end of the rod; changing the cross sectional areas of the alkoxyl chains at the end of the rod and the flexible alkyl chain. The research indicates that the self-assembly structures of these molecules transform from hexagonal column to rectangle column in liquid crystalline phase and form diameters increasing nanofiber structures in aqueous solution with the increase of the length of hydrophobic alkyl chains in the center of the rod. For molecules of alkoxyl chains at the end of the rod, with the increasing of the length of alkoxyl chains, an oblique columnar structure comes into being and then transfers into isotropic liquid. While changing the cross sectional areas of alkoxyl chains, with the increasing of the cross sectional areas, the molecules cannot form self-assembly at room temperature but forming rod-like micelle in aqueous solution. The n-shaped molecules containing octadecyl flexible chains self-assemble into layer structures in solid state, and have no liquid crystalline phase.Two categories of linear-typed molecules with several biphenyls as rod and with polyethylene oxide (PEO) or polypropylene oxide(PPO) as flexible chains are synthesized in the study of the linear-typed rod-coil liquid crystal oligomers with terphenyl in the rod block. we discuss the influence of the length of lateral chain in the center of the rod on molecular self-assembly structure as well as the self-assembly property of the molecule with an active group in the center of the rod. The results indicates that the introduction of longer lateral chain in the center of the rod building blocks will destroy the interaction ofπ-πstacking, thus makes the self-assembly structure of the molecules transform into disordered arrangement. The molecule with vinyl group in the center of the rod is performed by photo-polymerization in liquid crystalline phase. The resulting polymer can retain the nano-structure of the liquid crystalline phase, even though the temperature descends to room temperature.A series of molecules based on pyrene unit in the center of the rod, with the same volume fraction of the flexible chains and different cross sectional areas are synthesized in the study of the v-typed rod-coil liquid crystal oligomers. The influences on molecular self-assembly by the shapes of the rod (v-type and linear type) and the cross sectional areas of the flexible chains are discussed. The results imply that the dendritic chain with larger cross sectional area evidently destroys the self-assembly of rod building block. The molecules with line type rod prefer to form nematic phase in liquid crystalline phase, while the v-shaped molecules cannot form liquid crystalline phase.更多还原