Research On The Influence And Distortion Of Polymer Network On Electro-optical Properties Of Liquid Crystal Shutters

Liquid crystal displays have been applied widely in daily display for the dynamic image, the large-information capacity and the portability. But most displays need the polarizers which increase the loss of background light and decrease the viewing angle. The helical structure of cholesteric liquid crystals and guest-host mode can eliminate the dependence of polarizers. The polymer networks are introduced into cholesteric liquid crystal display to fasten the respond speed. Polymer-stabilized cholesteric texture (PSCT), as new technology of cholesteric liquid crystal displays, has obtained greatly development in displaying field due to several advantages such as low driving voltage, low power consumption, wide viewing angle.This paper has investigates the effect of Maxwell-Wagner-Sillars (MWS) polarization on PSCTs at normal mode. In the process of the preparation at normal mode, the applied electric-field induces the MWS polarization, resulting in the monomer with polar groups aggregated on the electrode surface. So a polymer layer formatted lowers the density of polymer networks and affects devices’ properties. Then the PSCTs doped with dichroic dye have been researched which can be applied for the color filter controlled by electric field. The dichroic dye with anisotropic absorbing effect has the maximum and minimum value of absorption at the planar and homeotropic texture, respectively. PSCTs not need polarizers because the absorption isn’t influenced by the direction of polarized light. Under the anchoring effect of polymer networks, PSCTs can fast respond between planar state and homeotropic state. Under the co-effect of three kind dyes, PSCTs doped by dye have ability to filter the visual light, and a colorful display gained consisted of the different emergent light.In addition, we also study the distortion of PSCTs at reverse-mode in the process switching between the planar state and homeotropic state, and analyze the factors such as the monomer structure, the morphology of polymer networks and the motion of liquid crystals. The results suggest that the interaction between liquid crystals and polymer networks induces the permanent distortion or elastic deformation. They can result in the liquid crystals that are stabilized in the focal conic texture, or remained in the homeotropic state. So the PSCTs cannot complete entire switching process.