Dolgov L. Electrooptics and structural peculiarities of the system "liquid crystal-nanoparticles-polymer

This thesis deals with structural peculiarities and electro-optical characteristics of the composites "liquid crystal-nanoparticles-polymer", which are formed during the phase separation of the polymer. The investigated composites can be divided into two groups, according to two limit cases of polymer phase morphology. The first group relates to the polymer stabilized filled nematics with the small amount of polymer. It was shown that in such composites along with the light scattering on the orientational defects of liquid crystal, the essential scattering due to the difference between refractive indices of the liquid crystal and nanoparticle's material occurred. This affects on the electro-optical contrast and angular dependence of transmittance. The second group includes the polymer dispersed liquid crystals filled with nanoparticles. It was determined that in the process of the photoinduced phase separation and formation of the capsulated liquid crystal, nanoparticles were mainly involved in the polymer phase. At the same time both the degree of optical inhomogeneity in polymer matrix and its effective refractive index were changed, that influenced on the difference between the refractive indices of liquid crystal and polymer that is on the electrically controlled part of the light scattering in the system. By means of optimization of material's refractive index, size and concentration of nanoparticles the on-state transmittance of the composite layers was flattened, what is important for the display applications of such systems. The necessity of careful selection and testing of the component's compatibility to prevent the chemical reactions between them is pointed in the work.