Liquid crystalline oligomers with a central core unit containing urethane groups

Here, we show a generic approach to synthesis of oligomers which include modelling LC main chain polymers, LC side chain polymers or LC dendrimers. Four new families of LC oligomers derived from 1,6-hexamethylene diisocyanate and their di- or trimers (uretdione, biuret or isocyanurate) and ω-hydroxyalkylated cyanobiphenyls were prepared. Their mesomorphic and optical properties were investigated by differential scanning calorimetry and polarised optical microscopy. Mesomorphic properties were crucially impacted by the structure of the central core spacer (urethane, uretdione, biuret or isocyanurate). Stabilisation of the LC state of synthesised oligomers was attributed to the H-bonding interactions confirmed by FTIR spectra.