Synthesis and phase behaviour of new carbazole containing liquid crystal side chain polysiloxanes

A series of chiral mesogenic side chain polymers containing a carbazole unit have been synthesized and investigated with regard to their liquid crystal (1c) phase behaviour. The carbazole units are linked either via the 2-position with a 1-oxycarbonyl-4-alkoxylphenyl moiety (end-on) or via the 9-position with an alkyl chain (side-on) to polymethylsiloxane. Only end-on polymers with long spacers or a ratio bigger one of spacer length and the free lateral alkyl chain length exhibit stable or metastable smectic phases. The side-on polymers are only isotropic or crystalline.