Polymer comprising cyclohexylene groups and its use in films with negative optical dispersion

Compounds of formula I

• wherein
• k is, in each occurrence independently of one another, 0 or 1, with k in at least one repeating unit being 1,
• m is, in each occurrence independently of one another, 0 or 1,
• n is an integer >1,
• R1, R2 are independently of each other straight-chain, branched or cyclic alkylene with 1 to 20, which is unsubstituted, mono- or polysubstituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR0—, —SiR0R00—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —SO2—, —CO—NR0—, —NR0—CO—, —NR0—CO—NR00—, —CY1═CY2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, or a single bond,
• Y1, Y2 are independently of each other H, F, Cl, CN or R0,
• R0, R00 are independently of each other H or alkyl with 1 to 12 C-atoms,
• X1, X2 are independently of each other a linkage group selected from the group consisting of —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—NR0—, —NR0—CO—, —NR0—CO—NR0—, —OCH2—, —CH2O—, —SCH2—, —CH2S—, —CF2O—, —OCF2—, —CF2S—, —SCF2—, —CH2CH2—, —(CH2)n1—, —(CF2)n1—, —CF2CH2—, —CH2CF2—, —CF2CF2—, —CH═CH—, —CY1═CY2—, —CH═N—, —N═CH—, —N═N—, —CH═CR0—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CR0R00— and a single bond,
• n1 is 1, 2, 3, 4, 5 or 6,
• B1, B2 are independently of each other a bivalent group having high polarisability selected from the group consisting of —C≡C—, —CY1═CY2—, optionally substituted aromatic or heteroaromatic groups, and combinations of the aforementioned,
• U1, U2 are independently of each other H or a monovalent group of formula II, wherein the asterisk denotes the linkage to the adjacent group B1 or B2, respectively
• R3, R4 are independently of each other straight-chain, branched or cyclic alkyl with 1 to 20, which is unsubstituted, mono- or polysubstituted by F, Cl, Br, I or CN, and wherein one or more non-adjacent CH2 groups are optionally replaced, in each case independently from one another, by —O—, —S—, —NH—, —NR0—, —SiR0R00—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —SO2—, —CO—NR0—, —NR0—CO—, —NR0—CO—NR00—, —CY1═CY2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, or a single bond,
• X3, X4 independently of each other have one of the meanings of X1,
• Z1 has in each occurrence independently of one another one of the meanings of X1,
• o is 0, 1, 2, 3, 4 or 5,
• G has one of the meanings of R1 or is a bivalent group of formula III
• —X5-A1-(Z2-A2)p-X6— III
• X5, X6 independently of each other have one of the meanings of X1,
• A1, A2 are independently of each other a carbocylic, heterocyclic, aromatic or heteroaromatic group, which is optionally substituted,
• Z2 has in each occurrence independently of one another one of the meanings of X1, and
• p is 0, 1, 2 or 3.