Monomers and their use for the production of a laser-optical recording element which can be repeatedly erased and recorded on

Claim 1

A polymer I (a) having chiral mesogenic pendant side groups (b) exhibiting ferroelectric smectic liquid crystalline behavior and (c) comprising monomer units which are derived from monomers of the structure I ##STR128## where R is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety, C is an optically active chiral molecular moiety and B is a mesogenic molecular moiety which consists of three or more aromatic nuclei bonded linearly or virtually linearly to one another and which is selected from the group consisting of i) moieties B which contain one or more naphth-2,6-ylene groups, ii) moieties B of the formula III ##STR129## where B 2 is a p-phenylene or a biphenyl-4,4'-diyl group Y is an ether, methylene ether (--CH 2 --O-- or --O--CH 2 --), ester ##STR130## or thioester group ##STR131## or a carbon-carbon single bond and m and n are each 0 or an integer ≧1; iii) moieties B of the formula IV ##STR132## where m and n and Y have the abovementioned meanings and B 3 is selected from the group consisting of the p-phenylene, the biphenyl-4,4'-diyl group and the group III-1 ##STR133## where Y has the abovementioned meanings; and iv) moieties B, selected from the group consisting of the groups X-1 to X-7 ##STR134## where Y has the abovementioned meanings and the groups X-1 to X-7 are bonded via the ether group to moiety A, with the proviso that the moiety C of the molecule is exclusively selected from the group consisting of the pinan-3-yl, the camphan-2-yl and the p-menthan-3-yl group and the group of the formula VII ##STR135## where R 3 is methyl or trifluoromethyl, x and r independently of one another are each 0 or 1 and s is an integer from 1 to 3, the group of the formula VIII ##STR136## where s has the abovementioned meaning, and the group of the formula IX ##STR137## where t, u and v independently of one another are each an integer of from 1 to 10 and t and u independently of one another may furthermore be 0, and y is 0 or 1, whenever one of the said groups X-1 to X-7 is selected for moiety B of the molecule.