LAUSR

ABSTRACT The polymer dispersed liquid crystal films doped with the low concentration γ-Fe2O3 nanoparticles coated with oleic acid were inverstigatited. The experimental results showed that the doped and un-doped polymer dispersed liquid crystal films were the similar surface morphologies, however their evolving curves of the capacitance with the applied voltage were different, as well as the transmission rate. The interpretations based on these differences were proposed, i.e. those came from the adsorbed free ions by the γ-Fe2O3 nanoparticles, instead of the electromagnetic properties of the γ-Fe2O3 nanoparticles. The effect of the free ions is equivalent to the negative dielectric constant and refractive index. Furthermore, the reduction of the free ion concentration due to the absorption in the doped polymer dispersed liquid crystal films can decrease the negative dielectric constant and refractive index, i.e. the effective dielectric constant and refractive index were increased. As a result, the contrast ratio increased significantly, and the driving and threshold voltages decreased distinctly. These results may be useful for electro-optics devices. GRAPHICAL ABSTRACT