SYNTHESIS AND LIQUID-CRYSTALLINE PROPERTIES OF THERMOTROPIC COPOLYCARBONATES

Copolycarbonates with flexible spacers have been prepared by melt cond ensation of 4,4'-bis[(2-hydroxyethyl)oxy]biphenyl, 1,5-bis[(2-hydroxye thyl)oxy]naphthalene and penta-respectively octamethylene diphenyl dic arbonate in varying concentrations. These random copolycarbonates show liquid crystalline behavior, with the formation of a nematic phase ov er a temperature range of maximum 22 degrees C respectively 47 degrees C, this for at least 75 mol-% of biphenyl units. Incorporation of 1,5 -bis[(6-hydroxyhexyl)oxy]naphchalene does not lead to liquid crystalli nity. Copolymers with 2,6-bis[(6-hydroxyhexyl)oxy]naphthalene and 4,4' -bis[(6-hydroxyhexyl)oxy]biphenyl show mesomorphic behavior, with the formation of a mesophase with a maximum width of 20 degrees C, for inc orporation up to 75 mol-% of either of the mesogenic units. Copolycarb onates which contain only biphenyl mesogenic units and which differ in the length of the flexible spacers were also obtained; they behave li quid crystalline over the entire composition range with maximum 34 deg rees C for the nematic phase region.