Synthesis and liquid crystalline behavior of three-arm urethane derivatives bearing protruded alkyoxylbiphenyls

Here, we describe an approach to synthesis of three-arm urethane derivatives bearing alkyloxybiphenyl units. Four new families of oligomers derived from 1,6-hexamethylene diisocyanate and their di- or trimers (uretdione, biuret or isocyanurate) and ω-hydroxyalkylated biphenyls were prepared. Their mesomorphic and optical properties were investigated by differential scanning calorimetry and POM. Mesomorphic properties were substantially impacted by the structure of the central core spacer (urethane, uretdione, biuret, or isocyanurate). The synthesized compounds shown the rich smectic polymorphism form from one to three different smectic phase. Stabilization of the LC state of synthesized oligomers was attributed to the H-bonding interactions confirmed by FT-IR spectra. The part of H-bonded urethane units is maximal for compounds with star-shaped central core.