FIELD-DEPENDENT SWITCHING ANGLE OF A COLUMNAR PYRENE

The switching behaviour of 6,8-tetrakis-((S)-2-(heptyloxy)propanoyloxy )pyrene was studied near room temperature in a monotropic columnar pha se. The switching angle (optical tilt angle) increases linearly with t he 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 st rengths. At field strengths up to 10 V mu m(-1), a voltage and tempera ture independent 0 to 90 per cent switching time of c. 650 mu s was me asured. The observations are explained in terms of deformation and unw inding of an intracolumnar helix.