Common Uses of Fluorochemicals
Perhaps the best-known use of fluorochemicals is seen in the addition of fluoride to drinking water, to help prevent tooth decay. Compounds such as sodium fluoride, and sodium monofluorophosphate also added to toothpastes to achieve a similar effect.
In the form of hydrofluoric acid, fluorine has been used to etch glass for several centuries. In fact, the earliest known use of hydrofluoric acid for this purposes dates back to approximately 1670. One notable modern use of hydrofluoric acid in this way is in the etching of glass lightbulbs.
Fluorochemicals are also notorious for their use in a wide variety of compounds known as chlorofluorocarbons, or CFCs. For example, dichlorodifluoromethane was once commonly used as a refrigerant in aerosol spray cans, refrigerators, and air conditioning units. However, as the damage CFCs caused to the Earth's ozone layer became more widely understood, the use of these chemicals has largely been phased out.
Fluorocarbons
The replacement of hydrocarbons with fluorocarbons has led to a variety of different applications. Fluorocarbon based chemicals have been used as anesthetics, refrigerants, propellants, solvents, lubricants, and in water and stain-repellent products.
Freon (which contains chlorine in addition to fluorine) has been used widely as refrigerants and propellants. However, the stable bonds that form between carbon and fluorine mean these compounds break down in the environment very slowly, and the addition of chlorine to fluorocarbons make these compounds destructive to the Earth's ozone layer. Concerns about long-term pollution have led to the discontinuation of the use of chlorofluorocarbons. Hydrofluorocarbons are used today and are non-reactive with the ozone layer.
Fluorocarbons were once widely used as industrial solvents. Due to ozone depletion concerns, some have been phased out; however fluorocarbons are still used for precision cleaning, particulate removal, as carrier fluids, and for other industrial applications.
Highly fluorinated fluorocarbon based chemicals are hydrophobic, which allows for excellent water-resistance and stain-repellant properties. Many stain-repellant products once contained chlorofluorocarbons. However, as with many other uses of these compounds, environmental concerns have led to many such products being phased out in favor of new formulas that contain non-reactive fluorocarbons rather than chlorofluorocarbons.
The stability and low flammability of some fluorocarbons, such as Teflon, make them highly popular for a wide variety of uses. Perhaps the best known use of Teflon is in the manufacture of non-stick Teflon-coated cookware. The very low friction of this substance, as well as its chemical and thermal stability, makes it useful in any number of moving parts such as bearings, gaskets, and gears. Interestingly, Teflon is such a low-friction compound that it is the only known surface to which a Gecko cannot stick!
Other Uses for Fluorochemicals
Fluorinated compounds are showing considerable promise in the pharmaceutical industry in a wide variety of applications. Fluorochemicals have been tested for antibacterial and antibiotic efficacy, as well as for use as anesthetics, protease inhibitors, and anticancer agents. In the latter case, elemental fluorine reacts with uracil (a molecule involved in DNA replication) to produce a new molecule called 5-fluorouracil, which is toxic to cancer cells.
In the agricultural industry, fluorinated compounds are used in insecticides, herbicides, and fungicides. In these types of applications the use of fluorine shows considerable promise. Fluorinated compounds have been shown to be more potent than their non-fluorinated counterparts. This increased potency allows for lower application rates than have previously been used.
Fluorine and fluorinated compounds can also be added to dyes. Increased chemical stability of fluorinated compounds improves the fixation yield of dyes, and also increases resistance to color degradation caused by light.
The addition of fluorine to compounds used in liquid crystal displays has been found to improve several of the chemical properties important for these types of applications. Adding fluorine improves viscosity, miscibility (the ability of the liquid to form a homogenous solution), and chemical stability of these compounds.
Fluorine is also added to compounds called photoresists. These are light-sensitive materials used for several industrial applications, including in photoengraving and photolithography, which are used to form patterned coatings on surfaces.
