Surface Tension of Binary Systems: Role of Polarity

The effect of polar and dispersive components on the spreading of a liquid on a solid substrate has long been established through numerous experimental as well as theoretical studies. This study demonstrates similar hypothesis for liquid-fluid interface verifying that the polar and dispersive components of the liquid and the vapor phases strongly effect the equilibrium surface tension of a binary system. In the case of volatile binary systems, the high mass flux across the liquid-vapor interface gives rise to substantial inaccuracies in surface tension measurements. We have developed a standard protocol for a wide range of liquid-vapor combinations, i.e., polar-polar, polar-nonpolar and nonpolar-nonpolar, which ensures accurate measurement of the surface tension. In doing so, we observed that the surface tension varies only if the molecular weight of vapor phase is lower than the liquid phase, which is not the case with a combination where the vapor phase is molecularly heavier.