Fluorinated microemulsions: A study of the phase behavior and structure

Fluorinated surfactants have been studied for their peculiar property to fo rm micellar aggregates in water and oils (hydrocarbons or fluorocarbons) an d to produce stable microemulsions. Because of their capacity to dissolve l arge amounts of gases (such as oxygen and carbon dioxide) and for their cha racteristic physicochemical properties, fluorocarbons have been tested for specific medical purposes and their microemulsions are among the most promi sing candidates for the production of suitable blood substitutes and other biocompatible fluids. We have synthesized a new partially fluorinated nonio nic surfactant, namely, F(CF2)(7)-CO-(OCH2CH2)(7.2)-OCH3 (I), that forms st able microemulsions with water and perfluorocarbons such as perfluorooctane (PFO). In this paper we describe for the first time the phase behaviors of perfluorooctanoic acid (PFOA) in water/PFH and in water/PFO, and that of e ater I in water/PFO. Small-angle neutron-scattering (SANS) experiments prov ide a detailed description of the microstructure of the H2O/PFO/PFOA ternar y system.