The effect of solvent surface tension on surface freezing in n-alkane solutions

Surface freezing was investigated in solutions of the n-alkane docosane, as a function of concentration, using solvents of both higher and lower surface tension (γ). The solvents of higher γ enhance the thermodynamic stability and thus the temperature range of the surface crystalline phase (ΔT), while lower γ decreases ΔT. This directional dependence is consistent with the theoretical explanation of surface freezing in alkanes being driven by the entropy of ordering competing with the relatively low solid-vapor and solid-liquid interfacial tensions of the ordered CH3- surfaces, compared to the higher liquid-vapor surface tensions.