Polymer containing aldehyde groups, reaction and crosslinking of this polymer, crosslinked polymer, and electroluminescent device comprising this polymer

1. A process for the preparation of a crosslinked polymer which comprises the following steps:

(a) providing a polymer which comprises at least one structural unit of the following formula (I):

wherein at least one representative from Ar and Ar′ contains an aldehyde group,

where the symbols and indices used have the following meanings:

Ar and Ar′ represent, independently of one another, a substituted or unsubstituted, mono- or polycyclic, aromatic or heteroaromatic ring system;

X represents a covalent single bond or a straight-chain, branched or cyclic C 1-10 -alkylene, C 1-10 -alkenylene or C 1-10 -alkynylene group, in which one or more H atoms is optionally replaced by F and in which one or more CH 2 groups is optionally replaced by O, NH or S; and

n is 1, 2, 3 or 4; and

the dashed lines represent bonds to the next structural unit of the polymer;

(b) conversion of the aldehyde groups into vinyl groups or alkenyl groups; and

(c) crosslinking of the polymer.

2. The process according to claim 1 , wherein Ar′ is a substituted or unsubstituted unit selected from the group consisting of the following:

phenylene, biphenylene, triphenylene, 1,1′:3′,1″-terphenyl-2′-ylene, naphthylene, anthracene, binaphthylene, phenanthrene, dihydrophenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzo[a]pyrene, fluorene, indene, indenofluorene, spirobifluorene, pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene and benzothiadiazothiophene.

3. The process according to claim 1 , wherein the structural unit of the formula (I) is a structural unit of the following formula (II):

wherein at least one Ar of the units Ar 1 to Ar 6 contains an aldehyde group,

where the symbols and indices used have the following meanings:

Ar 1 to Ar 6 are identical or different and represent, independently of one another, a substituted or unsubstituted, mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 25 ring atoms;

m is 0 or 1;

n is 0, 1 or 2;

the dashed lines represent bonds to the next structural unit of the polymer;

with the proviso that, if n=1, the two N atoms bond to different C atoms of the same aromatic ring system.

4. The process according to claim 3 , wherein Ar in the formula (I) or Ar 1 , Ar 2 , Ar 4 and Ar 5 in the formula (II) is (are) a substituted or unsubstituted unit selected from the group consisting of the following: 4,5-dihydropyrene, 4,5,9,10-tetrahydrofluorene, 9,9′-spirobifluorene, fluorene, phenanthrene, 9,10-dihydrophenanthrene, 5,7-dihydrodibenzoxepine, cis-indenofluorene, trans-indenofluorene, phenylene, thiophene, benzanthracene, carbazole, benzimidazole, oxepine and triazine.

5. The process according to claim 3 , wherein the polymer comprises a further structural unit which is different from the structural unit of the formula (I) and/or (II).

6. The according to claim 5 , wherein the further structural unit is a structural unit of the formula (I) and/or (II) which does not contain an aldehyde group.

7. The process according to claim 3 , wherein Ar′ in formula (I) or Ar 3 and/or Ar 6 in formula (II) contains an aldehyde group.

8. The process according to claim 3 , wherein the structural unit of the formula (II) is selected from the following structural units: