Mesomorphic behaviour of lamellar smectic phases in the binary mixture of non-mesogenic compounds

The binary mixture of two non-mesogenic compounds viz., Sodium Oleate (NaOl) and Ethylene glycol (EG) exhibits a very interesting liquid crystalline smectic phases at large range of concentration and temperatures. The mixture with lower concentration of Naol exhibits an Iso - Sm A - Sm D - Sm B - Sm E - Cry., sequentially when the specimen is cooled from its isotropic phase. The phase transition temperature for different concentrations of these mixtures was determined using Polarizing microscope along with hot stage. The different phases of these mixtures are identified using X-ray and microscope techniques. The temperature variation of the optical anisotropy is discussed. Helfrich potential and elastic modulus is estimated in the smectic phase using Helfrich model