NOVEL FERROELECTRIC AND ELECTROCLINIC ORGANOSILOXANE LIQUID-CRYSTALS

A new series of organosiloxane ferroelectric liquid crystalline materi als have been synthesized, and their mesomorphic and physical properti es have been characterized. The new series contains a siloxy chain att ached to the hydrocarbon chain at the nonchiral end of the molecule. A ll materials show a very low melting point (<5 degrees C) and exhibit chiral smectic A (SmA) and chiral smectic C (SmC) mesophases. The cha nges in the siloxy chain length strongly affect the mesomorphic behavi or and electrooptic properties of these materials. Increasing the numb er of siloxy units in the chain increases the temperature range of the SmA phase, with a concomitment decrease in the SmA-SmC transition te mperature. The electroclinic effect in the smectic A phase is characte rized by a large electroclinic coefficient (similar to 4 degrees V-1 m u m(-1) at T-T-Ac = 2 degrees C) and low switching time (<40 mu s) One of the materials shows one of the highest value of spontaneous polari zation P-s ever reported in the SmC phase for similar siloxane materi als with P-s = 342 nC cm(-2) at 25 degrees C.