LIQUID-CRYSTALLINE OF POLYESTERS AND POLYCARBONATES HAVING 4,4'-DIHYDROXYAZO- OR 4,4'-DIHYDROXYAZOXY-BENZENE AS A MESOGENIC UNIT

Semi-flexible polyesters made of 4,4 prime -dioxyazo - or 4,4 prime -dioxyazoxy-benzene mesogenic unit with alpha , omega -alkanedioyl spacer readily form a liquid crystalline phase, in contrast to the polyesters of 4,4 prime -dioylazo- or 4,4 prime -dioylazoxy-benzene with alpha , omega -alkanedioxy spacer. Reverse order of the ester-linkage between mesogenic unit and spacer affects the formation of liquid crystalline phase in a striking manner. The introduction of chiral unit into the alkyl spacer gives a cholesteric phase, and the cholesteric pitch varies with the composition of spacer group. Compared with the polyesters having alkyl spacer, polycarbonates containing oxyethylene sequences in the spacer group have an extremely low transition temperature to the nematic state. This would originate from the flexibility of oxyethylene unit.