【作者】 刘佳；

【导师】 张宝砚；

【作者基本信息】 东北大学 ， 高分子化学与物理， 2020， 硕士

【摘要】 三种以呋喃环为端基的新型液晶单体在该论文中被首次合成和研究并进行了相应的表征,同时利用呋喃环结构中的共轭双键,将聚合物与石墨烯通过发生Diels-Alder反应(DA反应),以共价键形式连接。在本论文中,报道了新型液晶单体及聚合物的合成,并将液晶聚合物通过DA反应有效的功能化石墨烯,运用多种手段对单体、聚合物和复合物的性能进行了研究。文章主要由两部分内容构成,第一部分:设计并合成了三种新型端基为呋喃环结构的液晶单体,并将其中两种单体Mb和Mc分别与烯丙氧基苯甲酸胆甾醇酯M1进行聚合,以含有7个H的聚甲基含氢硅氧烷为主链骨架,制备了两系列的侧链液晶聚合物。第二部分:由于聚合物侧链的呋喃环结构中含有共轭双键,具备与还原氧化石墨烯(RGO)进行DA反应的能力,以形成六元环的形式与石墨烯表面和边缘等处进行键接,制备聚合物-石墨烯复合材料。通过傅里叶红外(FT-IR)和核磁(1H-NMR)等表征手段确定了新型液晶单体的分子结构;通过差示扫描量热仪(DSC)确定了液晶单体及聚合物的熔点、玻璃化温度和清亮点等热力学信息;通过偏光显微镜(POM)观察了液晶单体及聚合物的织构特征并确定其相态类型;通过XRD测试得到的衍射峰,进一步确定液晶聚合物的相态和石墨烯的结构信息;利用拉曼光谱表征氧化石墨烯(GO)及RGO的制备程度并确认DA反应是否发生;利用热重分析仪(TGA)确定聚合物和复合物材料的热分解温度,以此分析各物质的热稳定性。实验结果表明,三种新型液晶单体的结构符合分子设计,并且三种单体均具有较宽的液晶相范围和较高的纯度;偏光显微镜下,三种单体和两系列聚合物均呈现了彩色的液晶织构,其中单体Mb、Md为向列相液晶,Mc为近晶相液晶,聚合物均为近晶相液晶;对石墨烯相关材料的表征主要是采用拉曼光谱,通过D峰与G峰的相对强度,可以了解石墨烯中碳原子的杂化情况,为DA反应的原料做准备。结合拉曼光谱和WAXD测试结果,综合分析表明:GO和RGO均成功制备,并且也确认了聚合物与石墨烯DA反应的发生;TGA测试结果表明聚合物及复合物热分解温度较高,均在320℃以上,具有较好的热稳定性,并且复合物的热分解温度随着体系中石墨烯含量的增多而升高。更多还原

【Abstract】 In this paper,three novel liquid crystal monomers with furan ring as the end group were synthesized and characterized for the first time.At the same time,the polymer and graphene were linked in the form of covalent bond through Diels Alder reaction(DA reaction)using conjugated double bond in furan ring structure.In this paper,the synthesis of new liquid crystal monomers and polymers is reported,and the properties of monomers,polymers and composites are studied by various means.This paper consists of two parts.The first part:three new liquid crystal monomers with furan ring structure were designed and synthesized.Two of them,Mb and Mc,were polymerized with cholesteryl allyloxybenzoate M1 respectively.Two series of side chain liquid crystal polymers were prepared with polymethylhydrosiloxane containing 7 H as the main chain skeleton.The second part:due to the conjugated double bond in the furan ring structure of polymer side chain,it has the ability of DA reaction with reduced graphene oxide(RGO),and bond with the surface and edge of graphene in the form of six membered ring to prepare polymer graphene composite.The molecular structure of the new liquid crystal monomer was determined by FT-IR and 1H-NMR,and the thermodynamic information such as melting point,glass transition temperature and clear point were determined by DSC.The texture characteristics of liquid crystal monomer and polymer were observed by polarized light microscope(POM),and the phase type was determined.The molecular layer spacing was calculated by the diffraction peak obtained by XRD,the phase state of liquid crystal polymer and the structure information of graphene were further determined.The degree of preparation of graphene oxide(GO)and RGO was characterized by Raman spectroscopy,and the DA reaction was confirmed.The thermal decomposition temperature of polymer and composite materials was determined by TGA to analyze the thermal stability of each material.The experimental results show that the structures of the three new liquid crystal monomers are in accordance with the molecular design,and the three monomers have a wide range of liquid crystal phases and high purity.Under POM,three kinds of monomers and two series of polymers show colorful liquid crystal textures,in which the monomers Mb and Md are nematic liquid crystal,Mc is sematic liquid crystal,and the polymers are sematic liquid crystal.The characterization of graphene related materials is mainly based on the Raman spectrum.Through the relative strength of D peak and G peak,we can understand the hybridization of carbon atoms in graphene and prepare for the raw materials of DA reaction.Combined with the results of Raman spectrum and WAXD test,the results show that:GO and RGO are successfully prepared,and the reaction between the polymer and graphene DA is confirmed.TGA test results show that the thermal decomposition temperature of polymer and composite is higher than 320℃,which has good thermal stability,and the thermal decomposition temperature of composite increases with the increase of graphene content in the system.更多还原