Teflon

Teflon is a synthetic fluoropolymer of tetrafluoroethylene, widely known for its exceptional chemical resistance, high-temperature stability, and extremely low coefficient of friction. It is a brand name owned by Chemours, a company spun off from DuPont, which first discovered the polymer. The material's unique properties, including non-reactivity and non-stick characteristics, have made it ubiquitous in industrial applications and consumer goods, most famously in cookware.

Chemical composition and properties

The chemical basis for the material is polytetrafluoroethylene (PTFE), a long-chain polymer consisting entirely of carbon and fluorine atoms. This molecular structure, with strong carbon–fluorine bonds, grants it remarkable inertness, making it resistant to attack by most chemicals, including strong acids like aqua regia and bases. It exhibits excellent thermal stability, maintaining its properties across a wide temperature range from cryogenic levels up to approximately 260°C (500°F). Its most noted characteristic is an extremely low surface energy, resulting in superb non-stick and hydrophobic properties, and it is also an excellent electrical insulator used in printed circuit board manufacturing.

Discovery and history

The polymer was discovered accidentally in 1938 by Roy J. Plunkett, a chemist working for Kinetic Chemicals, a joint venture between DuPont and General Motors. While researching new refrigerants, Plunkett found a white, waxy solid had polymerized inside a pressurized cylinder of tetrafluoroethylene gas. Recognizing its potential, DuPont patented the substance in 1941 and registered the Teflon trademark in 1945. Its first significant application was in the Manhattan Project, where it was used to coat valves and seals handling corrosive uranium hexafluoride. Commercial sales began after World War II, with its use in cookware pioneered by French engineer Marc Grégoire in the 1950s.

Production and manufacturing

Industrial production primarily involves the free-radical polymerization of tetrafluoroethylene (TFE) under pressure, often using initiators like ammonium persulfate. The process must be carefully controlled due to TFE's tendency to explosively decompose. The resulting polymer is processed into usable forms through techniques like paste extrusion for making wire insulation or skiving (shaving) blocks of the resin to produce thin tapes and sheets. For coating applications, such as on aluminum cookware, the resin is often dispersed in a liquid medium and applied as a primer and topcoat, then sintered at high temperature to form a continuous film.

Applications and uses

Its applications are vast and diverse due to its unique combination of properties. In the consumer realm, it is best known as a non-stick coating for frying pans, baking sheets, and irons. Industrially, it is used for seals, gaskets, and liners in chemical processing equipment, and as a dielectric in coaxial cable and computer chip manufacturing. The aerospace industry utilizes it in aircraft wiring, while the medical field employs it in implants like vascular grafts. It is also the key material in Gore-Tex fabrics and used as a thread sealant tape, commonly called plumber's tape.

Health and environmental concerns

Health concerns primarily focus on perfluorooctanoic acid (PFOA), a processing aid historically used in its manufacture. PFOA is a persistent organic pollutant and has been linked to certain health risks, including some cancers, in studies by agencies like the United States Environmental Protection Agency. Under pressure, DuPont and other manufacturers phased out PFOA use by 2015 under the PFOA Stewardship Program. When overheated above 260°C (500°F), PTFE coatings can decompose and release fumes that may cause polymer fume fever, a temporary flu-like condition in humans, and can be lethal to pet birds like parakeets.

Branding and related products

Teflon is a flagship brand of Chemours. The company has expanded the brand to include a family of high-performance polymers. These include Teflon AF (amorphous fluoropolymer), used in optical cladding, and Teflon FEP (fluorinated ethylene propylene), a melt-processable version. Other related branded products under the umbrella include finishes for textiles and carpets. The brand's association with non-stick surfaces is so strong that it has entered common parlance, with the term "Teflon" sometimes used metaphorically, as in "Teflon Don," to describe someone to whom criticism does not stick. Category:DuPont brands Category:Fluoropolymers Category:American inventions