Bis (p-Substitutedphenyl) terephthalates의 Nematic Group Efficiency Order에 대한 연구

The Study on Nematic Group Efficiency Order of Bis (p-Substitutedphenyl) terephthalates.

New compounds were synthesized and their thermal and liquid crystal properties were studied by the differential scanning calorimetry(DSC) and on a hot-stage of a polarizing microscope. The terminal substituent groups of the compound were varied : X = -H, -F, -Cl, -Br, -I, -NO2 , -CF3, -OC2H5 , -OC4H9 , -CN and –C6H5. The compounds of X = -C1，-OC2H5 , -OC4H9 . -CN, and -C6H5 were enantiotropically nematic. The compound of X = -Br and –NO2 were monotropically nematic. In contrast, the com pounds of X = -H, ~F, -I and -CF3 were not liquid crystals. The nematic group efficiency order of these compounds was in the order of -C6H5 〉 ~CN > -OC2H5 〉 -Br > -OC4H9 > -NO2 > -Cl.