Liquid Crystal - Polymer Composite Systems

Liquid Crystal Layers Confined Between Polymer Walls

The array of thin liquid crystal layers between polymer walls possess advanced electro-optics characteristics in comparison to other heterogeneous LC materials (Figures 1a and 1b). The orientation of liquid crystal inside each layer can be controlled using appropriate monomer material or reactive liquid crystal monomer mixed with based liquid crystal. This orientation can differ from one layer to the other by application of different electric field to striped and/or inter-digital electrodes in the process of polymer walls formation. The distance between the walls determines the electro-optical response of the cell (Figure 2).

Figure1 a. Homogeneously oriented layers of LC (6 mm) confined between polymer walls (3 mm).
Figure 1 b. Homogeneously oriented layers of LC (12 mm) confined between polymer walls (6 mm).

Figure 2. Dependence of the relaxation time in 20 mm cells on the distance between polymer walls.

Polymer Dispersed Liquid Crystals (Fast Switching Birefrigent Plate)

To prevent the formation of large droplets during the time of monomer polymerization we used a low frequency electric filed to create a turbulence motion in the solution. As a result we obtained a high-speed birefringent PDLC plate (see figure 1).

Figure 1. PDLC. Dynamics of electro-optical response.

The characteristics of PDLC are determined by the temperature of polymerization, which establish the rate of phase separation. Indeed this phase separation rate defines the droplet morphology: size, shape and density (Figure 2).

Figure 2.