Thermotropic liquid-crystalline main-chain polyesters containing cyclooctylene units, 6. Cholesteric copolymers

A series of chiral nematic copolymers were prepared based on the new mesogenic unit cis-1,5-cyclooctylene bis(p-hydroxybenzoate) (COHB). The copolymers were prepared by linking COHB coupled with (+)-3-methyladipic acid to COHB units combined with terephthalic acid and its bromo and nitro derivatives. A biphasic region was observed in most of the samples which made phase diagrams more difficult to establish. Mesophase stability could normally be sustained up to 50 mol-% content of the methyladipic acid group in the copolymer. They were also sensitive to both temperature changes and shearing forces.