Effects of silica nanoparticles on electro-optical properties of polymer-stabilized liquid crystals.

We control the pretilt angle of liquid crystals (LCs) by simultaneously doping silica nanoparticles (SNs) and reactive monomers into the LC cell. Application of AC high voltage (ACHV) to the cell compels the lifting force and the facilitation of polar groups to move the SNs and monomers toward the substrate surface. Polymer networks and SNs are stabilized at the substrate surface after UV exposure, sustaining the LCs at high pretilt angles. The deposited SNs on the substrate surface increases the anchoring energy of the substrate; the dispersed SNs in the cell decrease the relaxation constant of LCs. Therefore, the response time of the high-pretilted-polymer-stabilized LC cell is decreased. The method enables the control of the LC pretilt angle over a broad range. The slow response time of the polymer-stabilized LC cell from high monomer dose can also be prevented following the addition of SNs.