Abstracto

Optical and thermal studies on lyotropic nematic phase inmixture of non-mesogenic compounds

T.N.Govindaiah

We report the results of our studies on the optical and thermal properties of two non-mesogenic compounds, namely, N-Cetyl-N,N,N, trimethyl ammonium bromide (CTAB) and glacial acetic acid (GAA). The mixture exhibits very interesting schilieren texture of lyotropic nematic phase, smectic A (SmA), and SmE phases for all concentrations of CTAB sequentially when the specimen is cooled from its isotropic phase. The order parameter (S) of the lyotropic nematic phase is estimated with the help of temperature dependence of optical anisotropy from the measured refractive index and density data. The temperature variation of order parameter of the experimental curve is very well fitted with theMayer–Saupe theoretical curve. The formation of above phases has been confirmed by optical, X-ray and differential scanning calorimetry studies.