High memory effects in polymer dispersed chiral liquid crystals with negative dielectric anisotropy

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