| Active Matrix Liquid Crystal Display is a well-known term for TFT-LCD (Thin Film Transistor-LCD). With the advent of the portable notebook computer, the Active Matrix Liquid Crystal Display has become the most prominent display mode and the materials requirements for liquid crystals has changed dramatically. Fluorine-containing liquid crystals influence material properties and allow these to be tuned to achieve the desired outcome. In this dissertation, we designed and synthetized three kinds of novel fluorinated liquid crystal compounds with CF2O structure. Their liquid crystalline(LC) phase behavior was investigated thoroughly. Opto-electrical properties of monomers were also studied. The main results are as follows.1. Through 14 steps chemical reactions, three kinds of fluorinated liquid crystal compounds containing 1,2,3,4-Tetrahydro-naphthalene were synthesized and characterized. The chemical structures of the monemers were confirmed by FTIR,1H NMR and GC-MS. In the process of preparation of intermediate 4b and 4c, the optimal experimental conditions of Weinreb amide were investigated. The experiment demonstrated that the suitable operation conditions are toluene and pyridine as the reaction solvent with the 1:1.2 mole ratio of acyl chloride, N,O-dimethylhydroxylamine hydrochloride for 0.5h at 65～75 ℃. The yield can be up to 90%.2. The phase transition behavior was studied by polarized optical microscope and DSC. The experiment demonstrated that compound 12c has a monotropic nematic phase on cooling and compound 12a and 12b have no liquid crystal phase. The phase transition temperature is lower when the alkyl chains of compounds become longer. Through studying the opto-electrical properties, we found that the addition of novel compounds in the liquid crystal mixture were stable against UV irradiation and had low threshold voltage. Besides, the respond time was about 20ms. As a result, these novel compounds are potential materials used for TFT-LCD. |
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