Electro-optical and morphological properties of ultraviolet- and electron beam-cured monomer/liquid crystal mixtures

摘要

Polymer Dispersed Liquid Crystal(PDLC)films are obtained by phase separation induced by Ultraviolet(UV)and Electron Beam(EB)curing techniques. A binary system composed of a monomeric diacrylate and the nematic liquid crystal E7 was employed as initial reactive blend prior to the polymerization/cross-linking processes. The analysis of the electro-optical responses of the obtained PDLC films show certain advantages of EB-cured systems, forexample lower threshold and saturation voltages. Sample morphologies obtained from scanning electron microscopy observations showed a narrow size distribution of ellipsoidal-type LC droplets for EB-cured samples thus explaining the sharp increase of transmission values as a function of voltage. The slow increase of the transmission with voltage for UV-cured samples can be understood by the large size distribution of irregularly shaped droplets.