CONTINUOUS ANCHORING TRANSITION IN LIQUID-CRYSTALS

THE search for new ways of aligning liquid crystals1 is motivated by their potential for optical and optoelectronic device applications. Rubbing of surfaces coated with an 'aligning agent' can induce an orientational preference in adjacent liquid-crystal films. Most of these surface preparations produce strong anchoring, in which the alignment remains pinned to the surface-induced orientation. But it is expected that for weak interactions with the surface, anchoring transitions may be possible in which the liquid-crystal orientation can be changed continuously, as a function of temperature for example2. Here we show that an anchoring transition can be observed for liquid crystals in contact with fluoropolymers as aligning agents. We find that the phenomenon might be general, and suggest that it provides the possibility of controlling precisely the angle of liquid-crystal alignment, and a method of producing weak anchoring.