New low molar mass organosiloxanes with unusual ferroelectric properties

A new low molar mass chiral organosiloxane mesogen and its racemic analogue have been synthesized and their mesomorphic and ferroelectric properties investigated. The chiral derivative, denoted A∗B, exhibits one tilted enantiotropic ferroelectric smectic C mesophase over a broad temperature range, with very high tilt angles and moderate spontaneous polarization (36° and 19 nC cm−2 at 20°C). The achiral siloxane derivative, denoted A∗B, exhibits one broad enantiotropic smectic C phase. Preliminary electro-optic measurements indicate that the spontaneous polarization is weakly dependent on temperature between 10°C and 50°C, the latter being the S∗c to isotropic phase transition. The tilt angle and layer spacing are temperature independent, and current response times of less than 200 μs were measured at 25°C for fields of 10 V μ−1. These results are discussed in comparison with those for side chain polymer liquid crystal structures and other low molar mass ferroelectric materials.