HIGH MEMORY EFFECTS IN POLYMER-DISPERSED CHIRAL LIQUID-CRYSTALS WITH NEGATIVE DIELECTRIC ANISOTROPY

A cholesteric liquid crystal with negative dielectric anisotropy and w ith a visible wavelength selective reflection presents high memory eff ects when encapsulated in a polymer film. Three states at least are ac cessible within the same film: a reflecting state, a memory state, and a refreshed state. The last two states are stable over months. When t he samples were annealed, the memory state was no longer stable. By co mparing samples as they were annealed we tried to understand how the m emory effect was removed. (C) 1996 American Institute of Physics.