Basf Aktiengesellschaft

Kark-Heinz Etzbach

Gerhard Wagenblast

Volker Bach

Axel Paul

Wolfgang Brox

Novel laser-optical recording elements which can be repeatedly erased and recorded on contain recording layers (a) which exhibit enantiotropic, ferroelectric smectic liquid crystalline (S.sub.C*) behavior, so that they can be switched back and forth between two thermodynamically stable, optically distinguishable ferroelectric smectic liquid crystlaline S.sub.C* order states on exposure to a laser beam of sufficient luminous power, by applying an external electric field. The recording layers (a) themselves consist mainly or exclusively of novel polymers P having chiral mesogenic side groups. The novel polymers P are prepared using the novel monomers of the general formula I ##STR1## where R is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety, and C is an optically active chiral molecular moiety and B is a mesogenic molecular moiety composed of at least three aromatic nuclei which are bonded linearly or virtually linearly to one another, or they are prepared using the novel monomers I which contain specially selected molecular moieties B in a novel combination with selected molecular moieties C.

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Frankenthal, Germany

Kark-Heinz Etzbach