| 摘要 |
A liquid crystal medium based on a mixture of polar compounds contains an at least bifluorinated tris or tetra-phenylene compound A liquid crystal medium based on a mixture of polar compounds contains an at least bifluorinated tris or tetra-phenylene compound of formula (I) R11>, R12>H or up to 15C alkyl or alkenyl optionally substituted once by CN or CF3 or at least once by halogen, the alkyl or alkenyl groups optionally having one or more CH2 group replaced by -O-, -S-, 1,3-cyclobutylene, -CF2O-, -Ctriple boundC-, -OC-O- or -O-CO- with the O atoms not directly linked to each other; ring A : the following optionally halogen-substituted groups : (a) 1,4-cyclohexenylene or 1,4-cyclohexylene optionally with 1 or 2 non-adjacent CH2 groups replaced by -O- or -S-; (b) 1,4-phenylene with 1 or 2 CH groups optionally replaced by N; or (c) piperidin-1,4-diyl, 1,4-bicyclo[2.2.2]-octylene, a naphthylene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl or fluorene-2,7-diyl; and L1>-L6>H or F with at least 2 of L1>-L6> being F. [Image] |
