Mykytyuk Z. Structure and electro-optic properties of induced cholesteric liquid crystals

Object of study: Supermolecular structure and creation mechanism of supermolecular утворень in nematic matrixes and induced cholesterics on its base, and electrooptic effects in such systems. Aim of study: Regularities definition of induced cholesteric structure creation and its correlation with electrootic properties. Methods of study and equipment: small-angle X-ray scattering, small-angle light scattering, infrared spectroscopy, molecular computer simulation of investigated substrates, obtained electrooptic characteristics analyze, small-angle X-ray camera, differential scanning colorimeter, specterphotometr. Theoretical and practical results, novelty: The features of mesogeneous molecules structural organization is fixed for the induced cholesteric liquid crystals on the basis of nematic matrices, which are characterized by a straight cybotaxic structure. The process of light scattering is investigated for an induced cholesteric sample under the action of electric field, which occurs on focal-conicdomains and phase diffraction gratings created by helix structures. It is shown, that under the field action in process of texture transition the polydispersic focal-conic texture arises. It is shown, that induced cholesteric structural regularity growth is accompanied by a decreasing of critical fields of forward and inverse cholesteric-nematic transitions mainly due to induced helix pitch increasing. Increasing of the intensity of fluctuating layered structure period and correlation length in induced cholesterics testify of structural regularity degree growth. The growth of matrix's translational regularity leads to a decreasing of cholesteric molecules' twisting ability. It is shown, that induced cholesteric structural regularity growth is accompanied by a decreasing of critical fields of forward and inverse cholesteric-nematic transitions mainly due to induced helix pitch increasing. It is shown, that a field hysteresis loop relative value, which is a qualitative characteristic of optical transmittance, is defined by elasticity constants ratio K22/K33 in the case of weak anchoring with the limiting surface or by d/P0 ratio in the case of strong anchoring conditions at the limiting surfaces. Field of application: