| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 97 === Three series of liquid crystals were synthesized in this study. In the first part of this study, a rectangular liquid crystal, compound 8, with two ethynyl groups and two oxymethylene groups used to link to phenyl groups and biphenyl groups with the central phenyl core respectively exhibits smetic phases. This UV-curable liquid crystal has potential application in optical compensation film. In the second part of this study, we aim to synthesize two series of negative liquid crystals with either 4-(alkylbiphenylethynyl)-2,3-difluoro-1-alkoxybenzene (compound 14a-14f) or 4-(alkylbiphenylethynyl)-2,3-difluoro-1-n-hexylbenzene (compound 19a-19b) mesogenic core. All these two series of liquid crystals show s nematic phase. The melting points of compound 14a-14f are in the range of 86.8 to 119.5 ℃ while their isotropic temperatures are in the range from 179.6 to 215.4 ℃. Their mesogenic temperature ranges cover from 78 to 110 degrees. The milting points of compound 19a and 19b are 43.9 ℃ and 74.8 ℃ respectively while their clearing temperatures are 92 ℃ and 112 ℃. Their mesogenic temperature ranges cover from 36 to 57 degrees. They are suitable for formulating eutectic mixture and for the applications in PDLC, reflective liquid crystal display, and IR modulator.
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