Liquid-crystalline medium

A liquid-crystalline medium, which comprises:

• one or more compounds of the formula I
• one or more compounds of the formula II
• wherein
• R1 and R2 are each, independently of one another, alkyl having from 1 to 12 carbon atoms, in which one or two non-adjacent CH2 groups are optionally replaced by —O—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, and
• and one or more polymerizable compounds selected from those of the formula I*
• P1-Sp1-X1-A1-(Z1-A2)n-R I*
• in which
• R is H, F, Cl, CN, SCN, SF5H, NO2, straight-chain or branched alkyl having from 1 to 12 carbon atoms, in which one or two non-adjacent CH2 groups are optionally replaced by —O—, —S—, —CO—, —OCO—, —COO—, —O—COO—, —S—CO—, —CO—S—, —CH═CH— or —C≡C— in such a way that O and/or S atoms are not linked directly to one another, or R is —X2-Sp2-P2,
• P1 and P2 are each, independently of one another, acrylate, methacrylate or epoxy,
• Sp1 and Sp2 are each, independently of one another, a spacer group or a single bond,
• X1 and X2 are each, independently of one another, —O—, —S—, —OCH2—, —CH2O—, —CO—, —COO—, —OCO—, —OCO—O—, —CO—NR0—, —NR0—CO—, —OCH2—, —CH2O—, —SCH2—, —CH2S—, —CH═CH—COO—, —OOC—CH═CH— or a single bond.
• A1 and A2 are each, independently of one another, 1,4-phenylene, in which one or more CH groups are optionally replaced by N;
• 1,4-cyclohexylene, in which one or more non-adjacent CH2 groups are optionally replaced by O and/or S;
• 1,4-cyclohexenylene;
• 1,4-bicyclo[2.2.2]octylene;
• piperidine-1,4-diyl;
• naphthalene-2,6-diyl;
• decahydronaphthalene-2,6-diyl;
• 1,2,3,4-tetrahydronaphthalene-2,6-diyl;
• or indane-2,5-diyl;
• where all these groups may be unsubstituted or monosubstituted or polysubstituted by L,
• L is F, Cl, CN or alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having from 1 to 7 carbon atoms, in which one or more H atoms are optionally replaced by F or Cl,
• Z1 is —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —OCH2—, —CH2O—, —SCH2—, —CH2S—, —CF2O—, —OCF2—, —CF2S—, —SCF2—, —CH2CH2—, —CF2CH2—, —CH2CF2—, —CF2CF2—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR0R00 or a single bond,
• R0 and R00 are each, independently of one another, H or alkyl having from 1 to 4 carbon atoms, and
• n is 0, 1 or 2.