![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The existence of pre-transitional surface ordering and disordering at the liquid crystal-isotropic liquid interface has been established from the surface tension measurements. A spinning-drop technique has been used for this study. Measurements were carried out in the smectic A(SA), nematic (N) and isotropic (I) phases of the liquid crystals and reproducible results were obtained. The results suggest that the equilibrium value of γ changes discontinuously in the N and SA phases. The slope dγ/dT is positive for both the isotropic phase just above T NI as well as for the nematic phase just below it. Similar positive slope has been obtained in the vicinity of T AN. A positive value of dγ/dt implies excess surface order than that of the bulk interior. From the density measurements it has been observed that there is a correlation between the anomalies in the temperature dependence of surface tension and density in the isotropic phase.