| 摘要 |
The first object of the invention is to provide a liquid crystal compound that is stable to heat, light and so on, and has a large optical anisotropy, a large dielectric anisotropy and a low melting point. The second object is to provide a liquid crystal medium that is stable to heat, light and so on, has a broad temperature range of a liquid crystal phase, a large optical anisotropy and a large dielectric anisotropy, and exhibits an optically isotropic liquid crystal phase. The third object is to provide a variety of optical elements containing the liquid crystal medium, which can be used in a broad temperature range and has a short response time, a high contrast and a low driving voltage. A liquid crystal compound with branched alkyl or branched alkenyl as represented by formula (1), a liquid crystal medium (a liquid crystal composition or a polymer/liquid crystal composite material) containing the liquid crystal compound, and an optical element containing the liquid crystal medium are described.
In formula (1), R 1 is branched alkyl of C 3-20 or branched alkenyl of C 3-20 . The ring A 1 , A 2 , A 3 , A 4 or A 5 is 1,4-phenylene or 1,3-dioxane-2,5-diyl, for example. Z 1 , Z 2 , Z 3 and Z 4 are independently a single bond or C 1-4 alkylene, for example. Y 1 is fluorine, for example, m, n and p are independently 0 or 1, and 1‰¤m+n+p‰¤3. |
