| 摘要 |
<p>Liq. crystal mixts. having a DF discotic mesophase comprise at least two hexa-substd. triphenylene derivs. of formula (I) (where R is R'O, R', R'COO, R'-Ar-COO or R'O-Ar-COO; R' is 4-21C alkyl; Ar is p-phenylene). Mixts. of (I) form a DF (thread-like) mesophase at lower temps. than the individual cpds. They can be used in electro-optic display devices based on change in birefringence, change in optical rotation or dynamic scattering of light. Specified mixts. comprise (I; R is octanoyloxy) and either (I; R is p-octylbenzoyloxy) or (I; R is p-nonylbenzoyloxy). In display devices based on change in birefringence, the walls of the electro-optic cells are coated with parallel-oriented SiO2 layers which align the optical axes of the mols. of (I) parallel to each other and to the walls. In devices based on change in optical rotation, the SiO2 layers are oriented at right angles to each other, so that the mols. of (I) are aligned in a helical arrangement. In devices based on dynamic scattering, the walls of the cells are coated with mellitic acid, hexahydroxybenzene or hexahydroxytriphenylene, pref. by immersion in an aq. alcoholic soln. of these cpds.</p> |
