Thermodynamic study on phase transition at the water/undecyl alcohol interface

Abstract

The interfacial tension of the water/undecyl alcohol (UNA) system was measured as a function of pressure at various temperatures. The interfacial tension vs pressure and temperature curves were found to have a break point. It was shown that the volume, entropy, and energy of interface formation evaluated have negative values and change discontinuously at the pressure and temperature of the break point. The equations describing the phase transition at the interface of a binary two-phase system were developed and applied to the present system.It was proved thermodynamically that the phase transition takes place at the break point. Further, it was suggested that the transition was the one between expanded and condensed states of the interface.

Dihedral Angle of Lens and Interfacial Tension of Air/Long Chain Alcohol/Water Systems

“…This trend is in striking contrast to the one observed for hydrocarbon/water interfaces and has been discussed in terms of the interaction between hydroxide group and water molecules and the orientation of alcohol molecules enforced at the interface due to their amphiphilicity. 20,21 It is also seen that the C 10 OH system exhibits a higher interfacial tension at a higher temperature and a lower one at a lower temperature than the C 8 OH system. This may be explained as follows: the interaction between hydroxide group and water becomes gradually weak with increasing temperature and hence the transfer of molecules to the O/W interface at a higher temperature is not so energetically favorable compared with that at a lower temperature.…”

“…We have shown previously that the O/W interfacial films of the longer chain alcohol such as 1-undecanol and 1-dodecanol exhibit the phase transition between the expanded and condensed states. 20,21 The dihedral angle and the three kinds of interfacial tension of these systems have been measured recently: the preliminary results demonstrate the phase transition of interfacial film, the nonwetting oil lens, and the intruding of the water phase. The complete sets of the experimental data and the close examination of the phenomena will be published in our forthcoming paper.…”

Dihedral Angle of Lens and Interfacial Tension of Air/Long Chain Alcohol/Water Systems. 2

“…First the intruding may occur more probably, because it is expected that the values of γ AO and γ AW + γ OW approach each other with increasing hydrocarbon chain length of the alcohol, judging from our previous results given in ref , where γ AO , γ AW , and γ OW denote the interfacial tensions of the air/alcohol (A/O), air/water (A/W), and alcohol/water (O/W) interfaces, respectively. Second, it has been proved that the 1-undecanol/water and 1-dodecanol/water interfacial films exhibit the phase transition between the expanded and condensed states. , The interfacial tension and dihedral angle were measured as a function of temperature. Then the states and phase transition of the interfacial films, the wetting behavior, the intruding phenomenon, and the mutual relation among them are discussed thoroughly.…”

Solid–Liquid Phase Transition in the Octadecanoic Acid Film Adsorbed on the Toluene–Water Interface

“…6. The thermodynamic properties of the soluble adsorbed film, which is considered to be a monolayer in a first approximation (Gibbs monolayer), are described by parameters (p, T, c) [2,[36][37][38]. In the interface plane, this film can be both isotropic and anisotropic despite the isotropy of the bulk phases [39].…”