Perfluorocarbon (PFC), is a chemical that is used mainly for liquid ventilation. This chemical was developed in the 1940's under the Manhattan project. It is derived from hydrocarbons by replacing all the hydrogen atoms with fluorine atoms.
The perfluorocarbon liquids are clear, colorless, odorless, nonconducting, nonflammable and have a density which is about twice the density of water. The ability to carry respiratory gases, namely oxygen and carbon dioxide is what makes their use in liquid ventilation possible. With the carbon-fluorine (C-F) chemical bond being the strongest single bond encountered in organic chemistry, liquid PFCs are uniquely characterized by very high intramolecular bonding and very low intermolecular force.
Perflurocarbons are used in paints in order to allow them to spread easier (a direct result of the intramolecular characteristics). PFCs are also being used as fabric protectants in textile manufacturing and in medicine as blood substitutes and radiological imaging agents.
Perflurocarbons as gases, are greenhouse gases, that are covered by the Kyoto Protocol. Although total emissions are relatively small, PFCs are extremely potent greenhouse gases with a 100 years global warming potential of between 6500 and 9200.
sources:
http://classes.kumc.edu/cahe/respcared/liquidventilation/wikeper.html
http://glossary.eea.eu.int/EEAGlossary/P/perfluorocarbon
http://www.techtrans.temple.edu/ips/175TS.htm