Liquid crystalline cyclic oligosiloxanes with polar end groups

The series of cyclic oligosiloxanes having different attached mesogenic rigid cores and the polar end groups have been reported. The novel oligomers exhibit smectic A and E phases. The effects of the various central linking units and end terminal groups on mesomorphic properties are discussed. Mesophases were characterised by differential scanning calorimetry, polarizing optical microscope and X-ray diffraction.