Fluorosurfactants, or fluorinated surfactants, are synthetic organofluorine

Organofluorine

Organofluorine compounds are organic chemical compounds that contain carbon and fluorine bonded in the polarized and remarkably strong carbon–fluorine bond. Organofluorine compounds are diverse, they can be fluorocarbons, perfluorinated, or biologically synthesized mono-fluorinated compounds, among...

 chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

s that have multiple fluorine

Fluorine

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s. They can be polyfluorinated or fluorocarbon

Fluorocarbon

Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...

-based (perfluorinated

Perfluorinated compounds

A perfluorinated compound is an organofluorine compound with all hydrogens replaced by fluorine on a carbon chain—but the molecule also contains at least one different atom or functional group. Thus, PFCs have properties similar to fluorocarbons as they are fluorocarbon derivatives...

). As surfactants, they are more effective at lowering the surface tension

Surface tension

Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...

 of water than comparable hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 surfactants. They have a fluorinated "tail" and a hydrophilic "head." Some fluorosurfactants, such as PFOS, are detected in humans and wildlife.

Physical and chemical properties

Fluorosurfactants can lower the surface tension of water down to a value half of what is attainable by using hydrocarbon surfactants. This ability is due to the lipophobic nature of fluorocarbons, as fluorosurfactants tend to concentrate at the liquid-air interface. They are not as susceptible to the London dispersion force

London dispersion force

London dispersion forces is a type of force acting between atoms and molecules. They are part of the van der Waals forces...

, a factor contributing to lipophilicity, because the electronegativity

Electronegativity

Electronegativity, symbol χ , is a chemical property that describes the tendency of an atom or a functional group to attract electrons towards itself. An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus...

 of fluorine

Fluorine

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 reduces the polarizability

Polarizability

Polarizability is the measure of the change in a molecule's electron distribution in response to an applied electric field, which can also be induced by electric interactions with solvents or ionic reagents. It is a property of matter...

 of the surfactants' fluorinated molecular surface. Therefore, the attractive interactions resulting from the "fleeting dipoles" are reduced, in comparison to hydrocarbon surfactants. Fluorosurfactants are more stable and fit for harsh conditions than hydrocarbon surfactants because of the stability of the carbon–fluorine bond

Carbon–fluorine bond

The carbon–fluorine bond is a bond between carbon and fluorine that is a component of all organofluorine compounds. It is the strongest single bond in organic chemistry—and relatively short—due to its partial ionic character. The bond also strengthens and shortens as more fluorines are...

. Likewise, perfluorinated surfactants persist in the environment for that reason.

Economic role

Fluorosurfactants play a key economic role for companies such as DuPont

DuPont

E. I. du Pont de Nemours and Company , commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont was the world's third largest chemical company based on market capitalization and ninth based on revenue in 2009...

, 3M

3M

3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....

, and W. L. Gore & Associates (makers of Gore-Tex

Gore-Tex

Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W. L. Gore and Associates. It was co-invented by Wilbert L. Gore, Rowena Taylor, and Gore's son, Robert W. Gore. Robert Gore was granted on April 27, 1976, for a porous form of polytetrafluoroethylene with a...

 fabrics and other products) because they are used in emulsion polymerization

Emulsion polymerization

Emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomer, and surfactant. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer are emulsified in a continuous phase of water...

 to produce fluoropolymer

Fluoropolymer

A fluoropolymer is a fluorocarbon based polymer with multiple strong carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases.-History:Fluoropolymers were accidentally discovered in 1938 by Dr. Roy J...

s. Also, fluorosurfactants have two main markets: a $1 billion dollar annual market for inclusion into stain repellents, and a $100 million dollar annual market for inclusion into polishes, paints, and coatings. However, DuPont has had legal liabilities over the fluorosurfactant C8

Perfluorooctanoic acid

Perfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent...

/PFOA due to contamination of a population.

Health and environmental concerns

Some fluorosurfactants have caught the attention of regulatory agencies because of their persistence, toxicity, and widespread occurrence in the blood of general populations and wildlife, such as perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid

Perfluorooctanoic acid

Perfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent...

 (PFOA), and perfluorononanoic acid

Perfluorononanoic acid

Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also an environmental contaminant found in people and wildlife along with PFOS and PFOA.-Chemistry and properties:...

 (PFNA). As studies give evidence that longer fluorosurfactants are more bioaccumulative and toxic, some companies are marketing shorter fluorosurfactants. For example, 3M is marketing two fluorosurfactants based upon the 4 carbon perfluorobutanesulfonic acid

Perfluorobutanesulfonic acid

Perfluorobutanesulfonic acid is a chemical compound with a four carbon fluorocarbon chain and a sulfonic acid functional group. As an anion it functions as a stable fluorosurfactant because of the strength of carbon–fluorine bonds....

.