Studies On Properties Of Functional Liquid Crystals Films Preparation Based On Electro-optical Properties Of Liquid Crystals With Negative Dielectric Anisotropy

Polymer dispersed liquid crystal (PDLC) films are technologically important class of materials that find numerous applications as larger area flat displays, electrically switchable optical devices. switchable privacy windows and so on. In the normal-mode operation, they are in an opaque state (off-state) and can be turned into a transparent state (on-state) by controlling the liquid crystal (LC) molecule orientation by means of a suitable voltage. PDLC films were in a transparent state needing continuous power supply, so it is more practical and environmental protection to design energy saving mode LCD photoelectric device in today’s energy shortage.In this paper the thin films which can potentially function as the novel electrically switchable shutters were fabricated based on the commercially available liquid crystal media with negative dielectric anisotropy, and their microstructures and dynamic light scattering properties were investigated in detail by the in-suit formation of polymer networks. This paper proposes a methodology to prepare PDLC films working in the reverse-mode operation, where the ion-doped LCs with negative dielectric anisotropy (△ε) was locked by polymer walls. By using a novel polymer network and an ion-doped cholesteric liquid crystal (ChLC) with negative dielectric anisotropy. we successfully fabricated the bistable PDLC thin film by the optically-induced polymerization of acrylate monomers followed by the thermally curing of epoxy groups. It is successfully to solve the mechanical stability of the LC devices. The main research contents are as follows:(1) The microstructures and dynamic light scattering properties of ion-doped LC with negative dielectric anisotropy were investigated in detail by the in-suit formation of polymer networks. It was found that LCs/polymer composites can be used for fundamental insights of the LCs molecular movement during dynamic scattering and the factors which determine the microstructure and light scattering properties based on polymer-stabilized cholesteric textures.(2) This paper proposes a methodology to prepare PDLC films working in the reverse-mode operation, where the ion-doped nematic liquid crystals (NLCs) with negative dielectric anisotropy (△ε) was locked by polymer walls. The effect of the cylindrical holes with different diameters of photo masks and LC △ε on the electro-optical properties and transmittance wavelength range of 400-3000 nm light of samples were investigated using UV-VIS-NIR spectrophotometers. It was found that it exhibited very good electro-optical characteristics, high contrast ratio, and excellent infrared energy-efficient (5.4%) of films used as switchable low-e windows.(3) Reverse-mode PDLC films were prepared by secondary polymerization of the ion-doped ChLC with negative dielectric anisotropy (△ε) was locked by polymer walls. The effects of the cylindrical holes with different diameters of photo masks and the monomer content on the electro-optical properties of samples were investigated. It was found that Secondary polymerization monomer can be formed in the polymer wall micro structure effective three-dimensional network which can stabilize the cholesteric texture by polymer networks. The polymer morphology ensures memory effects of the orientational order present, and optimized the electro-optical properties of PDLC films.(4) Bistable PDLC films were prepared by first photo-curing through the acrylate groups, and then thermally curing the epoxy groups. It was found with proper polymer network, the devices can be switched between a transparent state and an opaque state by voltage pulses. No voltage has to be applied to sustain the states. The principal electro-optical properties depend on the morphology of the dispersed network, which in turn depends on the polymerization conditions. The concentration of the thermal polymer has a crucial influence on the electro-optical performance.