Macromolecular chemistry and physics vol:197 issue:2 pages:443-466
Copolycarbonates with flexible spacers have been prepared by melt condensation of 4,4'-bis[(2-hydroxyethyl)oxy]biphenyl, 1,5-bis[(2-hydroxyethyl)oxy]naphthalene and penta-respectively octamethylene diphenyl dicarbonate in varying concentrations. These random copolycarbonates show liquid crystalline behavior, with the formation of a nematic phase over 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 crystallinity. 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 incorporation up to 75 mol-% of either of the mesogenic units. Copolycarbonates which contain only biphenyl mesogenic units and which differ in the length of the flexible spacers were also obtained; they behave liquid crystalline over the entire composition range with maximum 34 degrees C for the nematic phase region.