| Abstract: | Mesomorphic copolymers were synthesized by incorporating varying ratios of azelaic acid and (+)-3-methyl adipic acid into copolyesters based upon 4,4′-dihydroxybiphenyl. Introduction of the phenylene (+)-3-methyl adipate unit broadens the temperature range of the nematic phase of the azelate homopolymer and, at the same time, produces a chiral nematic (cholesteric) mesophase which exhibits various iridescent colors. Circular dichroism measurements were used to determine the pitch of the cholesteric liquid crystals. The pitch decreased gradually with increasing temperature, and the inverse pitch increased in direct proportion to the molar content of the units containing (+)-3-methyl adipate. The twisted cholesteric structure could be conserved by quenching to produce films with various colors at room temperature. Annealing these films at a temperature immediately below that of the crystal–mesophase transition improved the regularity of the cholesteric structure. |
