Fluorinated chains at interfaces: Surface tension of fluorinated alcohols and their mixtures with hydrogenated alcohols

The ability of fluorinated liquids to dissolve large quantities of respiratory gases, allied to their biocompatibility and chemical inertness and has triggered their potential use in biomedical and therapeutic applications... [ view full abstract ]

The ability of fluorinated liquids to dissolve large quantities of respiratory gases, allied to their biocompatibility and chemical inertness and has triggered their potential use in biomedical and therapeutic applications such as perfluorocarbons-in-water emulsions for in vivo oxygen delivery (blood substitutes) and reverse water-in-PFC emulsions for pulmonary drug delivery in liquid ventilation.

The use of these micro-heterogeneous systems in biomedical applications implies being able to control, thus understand, the stability of the emulsions. The knowledge of the surface and interfacial tension in presence of effective co-surfactants is obviously of utmost importance to control the stability and performance of both water-in-FC and in FC-in-water emulsions.

This work focuses on the study of interfacial properties of co-surfactants used to stabilize PFC/water emulsions. The interfacial properties of fluorinated alcohols and their mixtures with the corresponding hydrogenated alcohols have been investigated in this work and used as model systems to understand the fundamental principles underlying their role as emulsion stabilizers.

The surface tension of the pure fluorinated alcohols was measured as a function of temperature. The surface tension of the mixtures was also measured as a function of composition at 293.15K. Interestingly, all mixtures display aneotropes, i.e., minima in the surface tension vs composition curve, which is a rather unusual behavior. Within a range of compositions, the surface tension of the mixture is lower than that corresponding to the surface being completely covered by the component with the lower surface tension. Molecular dynamics simulations were performed to model and interpret the experimental results.