| Polymer Network Liquid Crystal (PNLC) composite is a new functional material which has wide application and research value in the display. PNLC has a lot of advantages such as high brightness, large area, high information capacity, no polarization films, wide viewing angle, low threshold voltage and high response speed, etc. Based on the literatures, the chemical structure of the cross-linking monomer has important impact on the electrical-optical properties of PNLC. Whereas the monomers reported are compesed of acrylic as the end group. Here in, a novel monomer with vinyl as the end group was designed and synthesized, which was expected to improve the electrical-optical properties of PNLC.The main contents are as follows:1. A novel liquid crystal monomer with vinyl end groups,4-(4-vinyl phenyl) benzoic acid-(4-vinyl) phenyl ester, was synthesized via eight steps with the GC purity of99.6%and the total yield of5-9%. The structure was confirmed by1H-NMR, GC-MS and IR. The thermal properties of the target monomer was measured by POM and DSC. The results showed that, the target monomer was nematic liquid crystal, which was beneficial to improve the compatibility with the liquid crystal mixfure in PNLC application.2. The preparation methods and the synthesis conditions of some intermediates were improved and optimized.4-Acetyl-4’-formylbiphenyl was prepared by Grignard reaction with the advantages of less adverse reactions and high yield compared with Suzuki coupling reaction. Reaction conditions of oxidation of acetyl aromatic aldehydes with KMnO4under the anhydrous system were optimized by single-factor method. Under the best condition, the yield of4-(4-acetyl-phenyl) benzoic acid could be improved from75%to95%with the selectivity of100%. The best esterification condition was obtained by L9(34) orthogonal experiment with temperature of5℃, solvent of chloroform, the raw material of DCC and DMAP with the molar ratio of1:0.5:0.05and the reaction time of10h. |
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