Working modes of scattering PSLCs

Polymer networks formed in liquid crystals are anisotropic and affect the orientation of liquid crystals. They tend to align the liquid crystal in the direction of the fibrils. They are used to stabilize desired liquid crystal configurations and to control the electro-optical properties of liquid crystal devices. Polymer networks have been used to improve the performance, such as drive voltage and response times, of conventional liquid crystal devices such as TN and IPS displays. 

In order to scatter visible light strongly, the focal conic domain size has to be around the wavelength of the light. The main factors affecting the domain size are the pitch, polymer concentration, and curing UV intensity. The drive voltage is mainly determined by the pitch and the dielectric anisotropy of the liquid crystal. Faster response can be achieved with shorter-pitch CLCs. There is a hysteresis in the transition between the focal conic texture and the homeotropic texture, which also exists in pure CLCs. 

PSCT reverse-mode light shutter - This is also made from a mixtore of cholesteric liquid crystal (Ae 0) and a small amount of monomer. The pitch of the liquid crystal is a few microns (-3-15 pm). The mixture is placed into a cell with homogeneous alignment layers. The mixture is in the planar texture at zero field because of the alignment layers. The monomers are polymerized in the planar textore. The polymer network formed is parallel to the cell surface [43,53,54]. 

---