FTIR of liquid crystals. Organization and phase transitions in binary mixtures of nonylcyanobiphenyl and phenyl-cyclohexanecarboxylate

Abstract

Abstract The FTIR spectra of the isotropic and mesomorphic N, SAd , SA1 , SB and SG phases of 4-n-nonyl-4′-cyanobiphenyl (9CB), 4-n-pentylphenyl-trans-4′-n-pentylcyclohexane-1-carboxylate (5H5) and their binary mixtures have been recorded and analysed. Changes in absorbance related to spontaneous reorientation of the molecules at the phase transitions have been observed and assigned to the orientation of the transition dipoles of typical vibrations. The results are discussed in terms of the phase diagram obtained by D.S.C. and by optical microscopy.