SURFACE INTERACTIONS AND APPLIED-FIELD EFFECTS IN CHOLESTERIC HELICOIDAL AND BLUE PHASES

The electric-field dependence of the correlation region induced by a surface potential in cholesteric liquid-crystal phases is considered theoretically. Based upon arguments given for the helicoidal and cubic blue phases I and II, it is argued that recent experimental results on blue phase III rule out a cubic or icosahedral structure for this state but are consistent with one composed of cylindrical elements, in each of which the order is characterized by a curling or double-twist configuration. In the bulk, these flexible cylinders interlace and form a three-dimensional mesh. Near a boundary, however, they lie preferentially in the bounding plane as a consequence of the surface potential.