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]‐α‐methylstilbene and 4,4′‐bis[(6‐hydroxyhexyl)oxy]‐α‐methylstilbene For systematic IUPAC nomenclature see Experimental part. 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°C and 21°C, respectively. Amorphous polycarbonates were obtained when 1,5‐naphthalene or α‐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°C and 28°C, respectively, being observed.