ISSN: 2320-5407 Int. J. Adv. Res. 4(11), 425-431 425 Journal Homepage: - www.journalijar.com Article DOI: 10.21474/IJAR01/2100 DOI URL: http://dx.doi.org/10.21474/IJAR01/2100 RESEARCH ARTICLE STUDIES ON MOLECULAR INTERACTIONS OF LIQUID CRYSTALLINE MATERIALS USING THERMODYNAMIC AND ULTRASONIC TECHNIQUE. * T. N. Govindaiah 1 , B. N. Ramakrishna 2 and M. Basavanna 3 . 1. Research Centre, Post-Graduate Department of Physics, Government College (Autonomous), Mandya-571401, India. 2. Department of Physics, Government College for Women, Mandya-571401, India. 3. Post-Graduate Department of Computer Science, Government College (Autonomous), Mandya-571401, India. …………………………………………………………………………………………………….... Manuscript Info Abstract ……………………. ……………………………………………………………… Manuscript History Received: 24 September 2016 Final Accepted: 26 October 2016 Published: November 2016 Key words:- Optical studies: density and ultrasonic measurements: Adiabatic compressibility: Thermodynamical studies: We report the results of our studies on optical and thermal properties of ternary mixture of compounds, viz., laurylpyridinium chloride (LPC), cholesteryl nonanoate (CN) and orthophosphoric acid (H 3 PO 4 ). These mixture exhibits a very interesting cholesteric and induced reentrant smectic-A phases for different concentrations of CN sequentially when the specimen is cooled from its isotropic phase. The temperature variations of optical-density and ultrasonic measurements have been discussed. Thermodynamical response of birefringence has also been discussed to understand: the phase stability, chemical structure and molecular dynamics of the multi-component system of liquid crystalline materials. Copy Right, IJAR, 2016,. All rights reserved. …………………………………………………………………………………………………….... Introduction:- Generally the matter exists in three states, viz., solid, liquid and gas. Certain organic compounds show intermediate phases between crystalline solids and isotropic liquids, which are thermodynamically stable. These phases exhibit rheological behavior similar to the liquids but have anisotropic properties of crystalline solids and hence they are termed as liquid crystal phases [1-3]. Liquid crystals have been extensively investigated due to increasing importance in science and technological applications [4-7]. In the present investigation, we have shown the existence of induced reentrant smectic and cholesteric phases respectively at different concentrations in the multi-components, namely, cholesteryl nonanoate (CN), laurylpyridinium chloride (LPC) and Orthophosphoric acid (H 3 PO 4 ). These phases have been characterized by using optical anisotropic techniques for different concentrations and at different temperatures. In light of the above investigations, an attempt has been made to understand the coupling between aggregated structure and mesophase order [8]. Experimental Studies:- In the present study, we use the multi-component materials, namely, laurylpyridinium chloride (LPC), cholesteryl nonanoate (CN) and orthophosphoric acid (H 3 PO 4 ). Mixtures of different concentrations of CN in LPC+H 3 PO 4 were prepared and were mixed thoroughly and they were kept in desiccators for 6 hours. The samples were subjected to several cycles of heating, stirring and centrifuging to ensure homogeneity. Phase transition temperatures of these Corresponding Author:- T. N. Govindaiah. Address:- Research Centre, Post-Graduate Department of Physics, Government College (Autonomous), Mandya-571401, India.