SURFACE CHEMISTRY OF FLUOROCHEMICALS

Abstract

Abstract : With the advent of the highly fluorinated organic compounds, it has been possible to prepare surfaces having extremely low free surface energies, much lower than had previously been possible with hydrocarbon derivatives. Because of their low surface energies, fluorinated solids have the most nonwettable and nonadhesive surfaces known. It has been proved that only the outermost molecules of the surface of a solid need be highly fluorinated in order to achieve such low surface energies. In fact the most nonwetting surfaces studied to date were those covered with an adsorbed monolayer of closely packed perfluoro acids, with the perfluoromethyl (-CF3) groups outermost. It has likewise been found that surface-active agents containing perfluorocarbon terminal groups will lower the surface tension of water far below the values obtainable with hydrocarbon-type wetting agents. Certain fluorinated hydrocarbon derivatives have also been synthesized that show very high surface activity in a wide variety of organic liquids, the extent of surface activity being dependent upon the organophilic-organophobic balance in the fluorine-containing amphipathic molecule.