Peculiarities of thermo-morphologic and thermotropic transformations of heterophase regions: nematic <-> isotropic phase transition in 4-n-Alkyl-4 '-cyanobiphenyl mesogens

Abstract

Important peculiarity of phase transitions in liquid crystalline materials is availability of the heterophase regions, in which low temperature and high temperature phases simultaneously take place. In this work, peculiarities of the the thermo-morphologic and thermotropic transformations of the heterophase regions of phase transitions between nematic mesophase and isotropic liquid vs. boundary conditions have been investigated. 4-n-alkyl-4'-cyanobiphenyl liquid crystals with different length of the alkyl chain were objects of our investigations. Effect of thickness of liquid crystalline layer in the sandwich-cells on the thermo-morphologic and thermotropic properties of liquid crystals under investigations has been observed. Temperature and linear widths of the heterophase regions of phase transitions were determined with high accuracy. Change of the temperature and linear widths of the heterophase regions as function of thickness of liquid crystalline layer was found.