Untypical surface properties of aqueous solutions of 1,5-pentanediol

The surface tensions σ of aqueous solutions of 1,5-pentanediol were measured in the temperature range between 278 and 338 K using Wilhelmy plate method. They exhibit, in a wide range of concentrations, the S-shaped temperature dependencies with a region of positive dσ/dT, never reported before. The results were interpreted in terms of specific interactions of molecules adsorbed at the interface. Increasing surface concentration of diol molecules forming an interface causes their rearrangement, which microscopic structure strongly depends on temperature, most possibly agglomeration or formation of micelles.