FIELD-DEPENDENT SWITCHING ANGLE OF A COLUMNAR PYRENE

The switching behaviour of 1,3,6,8-tetrakis-((S)-2-(heptyloxy)propanoyloxy)pyrene was studied near room temperature in a monotropic columnar phase. The switching angle (optical tilt angle) increases linearly with the applied electric field from 0 degrees to c. +/- 10 degrees at +/- 0.35 degrees/(V mu m(-1)), then rapidly increases to its upper limit of 22 degrees. The electric polarization is roughly proportional to the switching angle with a maximum value of 110 nC cm(-2) at high field strengths. At field strengths up to 10 V mu m(-1), a voltage and temperature independent 0 to 90 per cent switching time of c. 650 mu s was measured. The observations are explained in terms of deformation and unwinding of an intracolumnar helix.