SYNTHESIS AND LIQUID-CRYSTALLINE PROPERTIES OF THERMOTROPIC HOMOPOLYCARBONATES

Six series of polycarbonates with flexible spacers have been prepared by melt condensation of aromatic diols such as 4,4'-bis[(2-hydroxyethyl)oxy]biphenyl, 4,4'-bis [(6-hydroxyhexyl)oxy]biphenyl, 1,5-bis[(2-hydroxyethyl)oxy]naphthalene, 1,5-bis[(6-hydroxyhexyl)oxy]naphthalene, 2,6-bis[2-hydroxyethyl)oxy]naphthalene, 2,6-bis[(6-hydroxyhexyl)oxy]naphthalene, 4,4'-bis[(6-hydroxyhexyl)oxy]stilbene, 3,3'-dimethyl-4,4'-bis[(2-hydroxyethyl)oxy]stilbene, 3,3'-dimethyl-4,4'-bis [(6-hydroxyhexyl)oxy]stilbene, 4,4'-bis[(2-hydroxyethyl)oxy]-alpha-methylstilbene and 4,4'-bis[(6-hydroxyhexyl)oxy]-alpha-methylstilbene with several alkylene diphenyl dicarbonates. Polycarbonates with biphenyl and stilbene mesogenic groups show liquid-crystalline behavior with the formation of a nematic phase over a temperature range of 46 degrees C and 21 degrees C, respectively. Amorphous polycarbonates were obtained when 1,5-naphthalene or alpha-methylstilbene groups are incorporated. Polymers with 2,6-naphthalene and 3,3'-dimethylstilbene groups show mesophase formation up to a certain spacer length, a transition range of 15 degrees C and 28 degrees C, respectively, being observed.