2-STAGE SWITCHING BEHAVIOR OF POLYMER STABILIZED CHOLESTERIC TEXTURES

The electro-optical behavior of polymer stabilized cholesteric texture cells has been investigated for three different polymers. The switchi ng process was studied with respect to the electric field dependence o f the diffuse reflectivity, diffuse transmittance, and the dynamics of the reorientation process. For certain polymer concentrations, a two- stage reorientation process was observed. This behavior is consistent with the cholesteric liquid crystal being divided between two distinct environments. In the first, the liquid crystal is strongly dominated by the polymer network, while in the second a bulklike behavior, compa rable to the unstabilized cholesteric material, is observed. Scanning electron micrographs of the polymer networks further support this mode l. Measurements of the diffuse scattering indicate that the polymer in fluenced regions contribute largely to the observed back scattering, w hereas the bulklike material contributes primarily to forward scatteri ng. (C) 1997 American Institute of Physics.