Preparation and Electro-optic Characteristics of Reverse-mode Polymer Stabilized Liquid Crystal Film

A novel reverse mode polymer stabilized liquid crystal(PSLC)electro-optic film—parallel reverse mode PSLC film was prepared by UV induced phase separation method.Polymer was synthesized from acrylate monomer 4′-(4-cyanophenyl)phenyloxybutyl methacrylate(CPMA).This film con- tained two glass substrates coated with parallel alignment layers instead of vertical alignment layers and positive nematic liquid crystal 5CB instead of chlosterical liquid crystal or negative liquid crystal, which were used in traditional reverse mode PSLC film.With the increase of applied electric field,the transmittance of reverse mode film decreased gradually.POM images demonstrated that CPMA con- tained polar rigid group and flexible chain could orient with LC molecules under the influence of the PI layer in the process of polymerization.The orientation of LC molecules made the film high transparent without the electric field.Although PCPMA,PAN and PMMA had the similar refractive indexes,in the same polymerization condition,film made from CPMA had much higher transmittance(82.3%) than two latter(23.3% and 18.9%).By application of a suitable electric field,this CPMA film can be switched from a transparent state to an opaque state due to mismatch between the refractive index of LC paralleled to the substrates because of the restriction of polymer network and that paralleled to the electric field.The concentration of monomer molecules and UV exposure time were important pa- rameters which influenced the electro-optical properties of film.The ratio of mass fraction between LC and monomer 6:1 was the best ratio for reverse mode PSLC,and the drive voltage was lower than 2.3 V·μm~(-1).