birefringence of nematic liquid crystal layers

The main refractive indices and the birefringence of MBBA and PPMAEBOBA10-2 g/cm3 in TCM nematic liquid crystals at room temperature were determined by interferometric means for some visible monochromatic radiations in the absence and in the presence of external electrostatic or alternate electric fields of different frequencies. This study revealed the increase in the degree of order with the magnitude of the electrostatic field acting on the MBBA thin layer at room temperature. The increase in the frequency of the external alternate electric field decreases the order degree of PPAMAECOBA in TCM lyotropic liquid crystal, showing that the dipolar collective interactions of the side chains of polymer are responsible for the liquid crystal nature of this mixture