ANNEALING AND MEMORY EFFECTS IN POLYMER-DISPERSED CHIRAL LIQUID-CRYSTALS

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: reflecting state, memory state, and ref reshed state. The last two states are stable over months. When the sam ple is annealed, the sample goes through an irreversible transformatio n, after which the memory state is no longer accessible. Through the d ata collected as the samples were progressively annealed it was guesse d how annealing changes the properties of the film, and which phenomen a are responsible for such changes. (C) 1996 American Institute of Phy sics.