Surface properties ofperfluorodecalin–containing liquid/liquid systems: The influence of Pluronic F-68 dissolved in the aqueous phase

Abstract

Perfluorodecalin (PFD) is extensively applied as liquid carrier of gaseous metabolites in systems for in vitro cultures of various types of cells. The influence of Pluronic F-68 on modification of the surface properties of few liquid/liquid system containing PFD was discussed. Static surface and interfacial tensions (σ) of water/PFD, culture medium/PFD, as well as air/water (referentially) two-phases systems with the aqueous phase contained nonionic 3-block copolymer Pluronic F-68, were measured by the du Noüy ring method at 25 °C and 37 °C. Values of critical micelle concentration (CMC) for Pluronic F-68 dissolved in water/PFD and air/water systems were similar at constant temperature. Smaller value of maximum surface excess (Γ∞) and higher value of minimum surface area per adsorbed molecule (Amin) were obtained for water/PFD, than for water/air system. Increase of temperature from 25 °C to 37 °C resulted in significant decrease of CMC, decrease of Γ∞ and increase of Amin. Calculated value of the standard Gibbs free energy of micellization was negative and became more negative for higher temperature, what indicated that micelles were formed spontaneously and the tendency for micelle formation increased with temperature increase. The Frumkin model fits well the experimentally obtained values of σ, what has been proved by the coefficient of determination equaled to 0.994–0.996.