Synthesis and Characterization of Liquid Crystal Polymer Ligand Containing T-type Two-Dimensional Liquid Crystal Element (II)

Synthesis and Characterization of Liquid Crystal Polymer Ligand Containing t-type Two-Dimensional Liquid Crystal Molecules (rbookmark0 Zhang Shuyuan, Zhang Zheng, Deng Gang, Zheng Shijun, Li Zifa Zhou Qifengbookmark1 (School of Chemistry and Chemical Engineering, Zhengzhou University, Zhengzhou 450052, Henan Province, China) Department of Molecular Science and Engineering, Beijing 100871, China) 4-Dihydroxy-44-g-oxyazobenzene was used as a monomer. A new class of liquid crystalline macromolecules with T-type bimeric mesogenic motifs was synthesized by solution polycondensation. Their liquid crystal behavior was characterized by DSC polarized light microscopy and X-ray diffraction. It was found that the macromolecule ligands are nematic thermotropic liquid crystal polymers, and the melting point (T) of the liquid crystalline polymer ligands is wide in the liquid crystal temperature range and The clear point (T,) of the liquid crystal state is designed to change with the increase of terminal alkoxyl groups in the molecule and to synthesize a new type of liquid crystal polymer, which has become one of the most interesting topics in polymer liquid crystals in recent years. The introduction of two-dimensional structure of liquid crystal motifs into polymer chains and synthesis of liquid crystal polymers containing two-dimensional liquid crystal motifs is a new direction of research. There have been several reports on the research work in this area. There are few studies on liquid crystal macromolecules containing two-dimensional liquid crystal motifs of coordinating atoms. The author designed and synthesized liquid crystal polymer ligands containing T-type two-dimensional liquid crystal motifs. One is that molecules contain coordinating atoms. It forms liquid crystal complexes with metals. Second, it has a stretched chain structure similar to that of rodlike liquid crystal polymers and the intermolecular interaction force is expected to be strengthened. (This work will be reported in another article.) It is of great interest to understand the relationship between the structure and properties of liquid crystal polymers and the effect of metal ions on the performance of liquid crystals. MAX-3B X-ray diffractometer, Cu target, operating voltage 40kV, operating current 30mA, scan rate 5/min, scanning range 5~ GPCWaters201 type instrument, standard sample PS; Leitz hot stage polarizing microscope 1. As can be seen in Fig.1, there is a melting peak from the solid state into the liquid crystal state during heating, and there is no liquid crystal state except 4A. Enter the clear peaks of the isotropic state.

The result of the hot stage polarizing microscope and DSC measurement is consistent.

The birefringence of the sample at room temperature is weaker, indicating that the ligand has a certain degree of crystallinity. As the temperature rises, the sample melts and enters the liquid crystal state. Birefringence increases gradually, showing a nematic pattern of filaments and schlieren. Fig.2 4A and 4E liquid crystal image. During the observation, it was also found that there was no change in the liquid crystal texture to weak decomposition of the sample, indicating that they had only one liquid crystal phase state; the viscosity of the different samples after entering the liquid crystal state was different, and the terminal alkoxy group increased with the molecule. The apparent increase in fluidity reflects the influence of the size of the terminal groups on the ease of movement of the liquid crystal macromolecule ligands. It is particularly worth mentioning that the presence of 4A with no substituent at the end can also generate a liquid crystal state, which generates liquid crystal states. The mechanism and liquid crystal texture provide a new research topic. The WAXD mortar of the ligand shows that the ligands of different substituents have poor crystallinity, and the crystallinity of 4C and 4E is better, and 4B and 4D times at room temperature. The degree of crystallinity is different. Fig. 4E powder 4A-4E heated to the liquid crystal state, constant temperature 10min, WAXD curve measured at room temperature in the ice salt product can be seen from the figure, WAXD curve measured after quenching 4A, peak package center The location is about square 20, which is consistent with the general freeze-nematic liquid crystal polymer characteristics