Editing Polytetrafluoroethylene

{{short description|Synthetic polymer}}
{{Redirect|Teflon}}
{{Use dmy dates|date=September 2020}}
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| IUPACName      = Poly(1,1,2,2-tetrafluoroethylene)<ref>
 {{cite web
  | url=http://www.ebi.ac.uk/chebi/searchId.do?chebiId=53251
  | title=poly(tetrafluoroethylene) (CHEBI:53251)
  | access-date=12 July 2012
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| SystematicName = 
| OtherNames     = Fluon, Poly(tetrafluoroethene), Poly(tetrafluoroethylene), Teflon
| Section1       = {{Chembox Identifiers
 | Abbreviations = PTFE
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| Section2       = {{Chembox Properties
 | Formula = (C<sub>2</sub>F<sub>4</sub>)<sub>n</sub>
 | Density = 2200{{nbsp}}kg/m<sup>3</sup>
 | MeltingPt = 327&nbsp;[[Celsius|°C]]
 | ThermalConductivity = 0.25&nbsp;W/(m·K)
 | ElectricalResistivity = 10<sup>18</sup>&nbsp;Ω·cm{{efn|Dielectric. Bulk resistivity.<ref>{{cite web |url=http://www.microwaves101.com/encyclopedia/PTFE.cfm |title=PTFE |work=Microwaves101 |access-date=16 February 2012 |archive-date=16 July 2014 |archive-url=https://web.archive.org/web/20140716201011/http://www.microwaves101.com/ENCYCLOPEDIA/PTFE.cfm |url-status=dead }}</ref>}}
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'''Polytetrafluoroethylene''' ('''PTFE''') is a synthetic [[fluoropolymer]] of [[tetrafluoroethylene]], and has numerous applications because it is [[chemically inert]].<ref>{{cite web |url=https://www.thepipettepen.com/ask-a-toxicologist-is-it-safe-to-use-teflon-pans/ |website=The Pipettepen |access-date=22 December 2024 |title=Ask a Toxicologist: Is it safe to use Teflon pans? – the Pipettepen |date=6 July 2015 }}</ref> The commonly known brand name of PTFE-based composition is '''Teflon''' by [[Chemours]],<ref name=":0">{{cite web|last=|first=|date=|title=The History of Teflon Fluoropolymers|url=https://www.teflon.com:443/en/news-events/history|archive-url=|archive-date=|access-date=2021-02-03|website=Teflon.com|language=en}}</ref> a [[corporate spin-off|spin-off]] from [[DuPont (1802–2017)|DuPont]], which originally invented the compound in 1938.<ref name=":0" /> 

Polytetrafluoroethylene is a [[fluorocarbon]] [[solid]], as it is a high-[[molecular-weight]] [[polymer]] consisting wholly of [[carbon]] and [[fluorine]]. PTFE is [[hydrophobic]]: neither water nor water-containing substances [[Wetting|wet]] PTFE, as fluorocarbons exhibit only small [[London dispersion force]]s due to the low [[polarizability|electric polarizability]] of fluorine. PTFE has one of the lowest [[Friction#Coefficient of friction|coefficients of friction]] of any solid.

Polytetrafluoroethylene is used as a [[non-stick coating]] for [[Cookware and bakeware|pans]] and other [[Cookware and bakeware|cookware]]. It is [[Chemically inert|non-reactive]], partly because of the strength of [[carbon–fluorine bond]]s, so it is often used in containers and [[Piping|pipework]] for reactive and [[Corrosion|corrosive]] chemicals. Where used as a [[lubricant]], PTFE reduces friction, wear, and energy consumption of machinery. It is used as a graft material in surgery and as a coating on [[catheter]]s.

PTFE and chemicals used in its production are some of the best-known and widely applied per- and polyfluoroalkyl substances ([[Per- and polyfluoroalkyl substances|PFAS]]),<ref name=":0xd">{{Cite book |title=Fluorinated polymers |date=2017 |publisher=Royal Society of Chemistry |isbn=978-1-78262-917-7 |editor-last=Améduri |editor-first=B. |series=RSC polymer chemistry series |location=Cambridge, UK |oclc=951763265 |editor-last2=Sawada |editor-first2=Hideo }}{{pn|date=October 2024}}</ref> which are [[Persistent organic pollutant|persistent organic pollutants]]. PTFE occupies more than half of all fluoropolymer production, followed by [[Polyvinylidene fluoride|polyvinylidene fluoride (PVdF)]].<ref name=":0xd" />

For decades, DuPont used [[perfluorooctanoic acid]] (PFOA, or C8) during production of PTFE, later discontinuing its use due to [[Perfluorooctanoic acid#Legal actions|legal actions]] over [[Ecotoxicology|ecotoxicological]] and [[Perfluorooctanoic acid#Health effects|health effects of exposure to PFOA]].<ref>{{cite web | last=Rich | first=Nathaniel | title=The Lawyer Who Became DuPont's Worst Nightmare | website=The New York Times | date=2016-01-06 | url=https://www.nytimes.com/2016/01/10/magazine/the-lawyer-who-became-duponts-worst-nightmare.html | access-date=2024-10-14}}</ref><ref>{{cite web | last=Gillam | first=Carey | title=Top US chemical firms to pay $1.2bn to settle water contamination lawsuits | website=the Guardian | date=2023-06-02 | url=https://www.theguardian.com/environment/2023/jun/02/dupont-pfas-settlement-water-chemical-contamination | access-date=2024-10-14}}</ref> DuPont's spin-off Chemours currently manufactures PTFE using an alternative chemical it calls [[GenX]], another PFAS. Although GenX was designed to be less persistent in the environment compared to PFOA, its effects may be equally harmful or even more detrimental than those of the chemical it has replaced.<ref name="genx-more-toxic">{{Cite web |title=US EPA deems two GenX PFAS chemicals more toxic than PFOA |url=https://cen.acs.org/environment/persistent-pollutants/US-EPA-deems-two-GenX-PFAS-chemicals-more-toxic-than-PFOA/99/i40 |access-date=2024-10-14 |website=Chemical & Engineering News |language=en}}</ref><ref name="epa-human-genx-toxicicty">{{cite web |title=Fact Sheet: Human Health Toxicity Assessment for GenX Chemicals |url=https://www.epa.gov/system/files/documents/2023-03/GenX-Toxicity-Assessment-factsheet-March-2023-update.pdf |date=March 2023 |publisher=United States Environmental Protection Agency |access-date=October 14, 2024}}</ref>

== History ==
[[File:Happy Pan Poster.jpg|left|thumb|upright|Advertisement of the Happy Pan, a Teflon-coated pan from the 1960s]]{{external media |width = 210px [https://www.sciencehistory.org/distillations/podcast/teflon "From stove tops to outer space... Teflon touches every one of us some way almost every day."], Roy Plunkett, [[Science History Institute]]}}
[[File:1963 Zepel advertisement.jpg|thumb|upright|Advertisement for Zepel, the trade name used to market Teflon as a fabric treatment]]
[[File:EL-1994-00019.jpeg|thumb|upright|PTFE thermal cover showing impact craters, from NASA's Ultra Heavy Cosmic Ray Experiment (UHCRE) on the [[Long Duration Exposure Facility]] (LDEF)]]
[[File:Teflon logo.svg|thumb|Logo of Teflon, the commonly known brand name of PTFE-based compositions manufactured by Chemours]]

Polytetrafluoroethylene (PTFE) was accidentally discovered in 1938 by [[Roy J. Plunkett]] while he was working in Chemours Chambers Works plant in New Jersey for [[DuPont]]. A team of Dupont chemists attempted to make a new [[chlorofluorocarbon]] refrigerant, called [[tetrafluoroethylene]]. The gas in its pressure bottle stopped flowing before the bottle's weight had dropped to the point signaling "empty". John J. Beall (chemist), noticing a weight differential in his test cylinder, brought it to the attention of Roy Plunkett.  The chemists in the lab sawed the bottle apart and found the bottle's interior coated with a waxy white material that was oddly slippery. Analysis showed that it was polymerized perfluoroethylene, with the iron from the inside of the container having acted as a catalyst at high pressure.<ref name="Institute">{{cite web |title=Roy J. Plunkett |url=https://www.sciencehistory.org/historical-profile/roy-j-plunkett |website=Science History Institute |date=June 2016 |access-date=10 February 2020}}</ref> Kinetic Chemicals patented the new fluorinated plastic (analogous to the already known [[polyethylene]]) in 1941,<ref>{{Cite patent|inventor-last = Plunkett|inventor-first = Roy J|inventorlink = Roy Plunkett|issue-date = 4 February 1941|title = Tetrafluoroethylene polymers|country-code = US|patent-number = 2230654}}</ref> and registered the Teflon trademark in 1945.<ref name="fluoroboom">{{cite news|title = History Timeline 1930: The Fluorocarbon Boom|url = http://www2.dupont.com/Refrigerants/en_US/sales_support/history_1930.html|access-date = 10 June 2009|publisher = DuPont|archive-date = 3 July 2011|archive-url = https://web.archive.org/web/20110703073623/http://www2.dupont.com/Refrigerants/en_US/sales_support/history_1930.html|url-status = dead}}</ref><ref>{{cite news|title = Roy Plunkett: 1938|url = http://www2.dupont.com/Heritage/en_US/1938_dupont/1938_indepth.html|access-date = 10 June 2009|archive-date = 17 February 2012|archive-url = https://web.archive.org/web/20120217011800/http://www2.dupont.com/Heritage/en_US/1938_dupont/1938_indepth.html|url-status = dead}}</ref>

By 1948, DuPont, which founded Kinetic Chemicals in partnership with [[General Motors]], was producing over {{convert|2,000,000|lb|order=flip}} of Teflon-brand polytetrafluoroethylene per year in [[Parkersburg, West Virginia]].<ref>''[[American Heritage of Invention & Technology]]'', Fall 2010, vol. 25, no. 3, p. 42</ref> An early use was in the [[Manhattan Project]] as a material to coat valves and seals in the pipes holding highly reactive [[uranium hexafluoride]] at the vast [[K-25]] [[enriched uranium|uranium enrichment]] plant in [[Oak Ridge, Tennessee]].<ref name="rhodes">{{cite book |last1=Rhodes |first1=Richard |title=The Making of the Atomic Bomb |date=2012 |publisher=Simon and Schuster |isbn=978-1-4391-2622-6 |page=494 }}</ref>

In 1954, Colette Grégoire urged her husband, the French engineer [[Marc Grégoire]], to try the material he had been using on fishing tackle on her cooking pans. He subsequently created the first PTFE-coated, [[non-stick pans]] under the brand name [[Tefal]] (combining "Tef" from "Teflon" and "al" from aluminium).<ref name="history">{{cite web|archive-date = 14 February 2008|website = Useless Information|url = http://home.nycap.rr.com/useless/teflon/index.html |archive-url=https://web.archive.org/web/20080214150646/http://home.nycap.rr.com/useless/teflon/index.html |title=Teflon |publisher=home.nycap.rr.com}}</ref> In the United States, [[Marion A. Trozzolo]], who had been using the substance on scientific utensils, marketed the first US-made PTFE-coated pan, "The Happy Pan", in 1961.<ref name="intofire">{{cite news |id={{ProQuest|110883381}} |last1=Robbins |first1=William |date=21 December 1986 |url=https://www.nytimes.com/1986/12/21/us/teflon-maker-out-of-frying-pan-into-fame.html |title=Teflon Maker: Out of a Frying Pan Into Fame |newspaper=[[New York Times]] |url-access=subscription }}</ref> Non-stick cookware has since become a common household product, now offered by hundreds of manufacturers across the world.

The brand name Zepel was used for promoting its stain-resistance and water-resistance when applied to fabrics.<ref>{{cite news |last=Fenton |first=Lois |date=1992-01-02 |title=Go, spot, go Teflon enters fashion world as a protective coating |url=https://www.baltimoresun.com/news/bs-xpm-1992-01-02-1992002050-story.html |work=Baltimore Sun |archive-url=https://web.archive.org/web/20210620172022/https://www.baltimoresun.com/news/bs-xpm-1992-01-02-1992002050-story.html|archive-date=2021-06-20}}</ref>

In the 1990s, it was found that PTFE could be radiation [[cross-linked]] above its melting point in an oxygen-free environment.<ref name="autogenerated655">{{cite journal |last1=Sun |first1=Jiazhen |last2=Zhang |first2=Yuefang |last3=Zhong |first3=Xiaoguang |last4=Zhu |first4=Xianglin |title=Modification of polytetrafluoroethylene by radiation—1. Improvement in high temperature properties and radiation stability |journal=Radiation Physics and Chemistry |date=December 1994 |volume=44 |issue=6 |pages=655–659 |doi=10.1016/0969-806X(94)90226-7 |bibcode=1994RaPC...44..655S }}</ref> [[Electron beam processing]] is one example of radiation processing. Cross-linked PTFE has improved high-temperature mechanical properties and radiation stability. That was significant because, for many years, irradiation at ambient conditions has been used to break down PTFE for recycling.<ref>[http://www.e-beamservices.com/chain.htm Electron Beam Processing of PTFE] {{Webarchive|url=https://web.archive.org/web/20130906131658/http://e-beamservices.com/chain.htm |date=6 September 2013 }} E-BEAM Services website. Accessed 21 May 2013</ref> This radiation-induced [[chain scission]] allows it to be more easily reground and reused.

[[Corona treatment|Corona discharge treatment]] of the surface to increase the energy and improve adhesion has been reported.<ref>{{cite book |doi=10.1016/B978-1-895198-85-0.50009-1 |chapter=Degradation by Other Forms of Radiation |title=PVC Degradation and Stabilization |date=2015 |last1=Wypych |first1=George |pages=215–226 |isbn=978-1-895198-85-0 }}</ref>

== Production ==
PTFE is produced by [[free-radical]] [[polymerization]] of [[tetrafluoroethylene]].<ref>{{cite journal |last1=Puts |first1=Gerard J. |last2=Crouse |first2=Philip |last3=Ameduri |first3=Bruno M. |title=Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer |journal=Chemical Reviews |date=28 January 2019 |doi=10.1021/acs.chemrev.8b00458 |volume=119 |issue=3 |pages=1763–1805|pmid=30689365 |s2cid=59338589 |hdl=2263/68582 |hdl-access=free }}</ref> The net equation is as follows:
: ''n'' F<sub>2</sub>C=CF<sub>2</sub> → −(F<sub>2</sub>C−CF<sub>2</sub>)<sub>''n''</sub>−
Because tetrafluoroethylene can explosively decompose to [[tetrafluoromethane]] ({{chem2|CF4}}) and carbon, a special apparatus is required for the polymerization to prevent hot spots that might initiate this dangerous side reaction. The process is typically initiated with [[Peroxydisulfate|persulfate]], which [[Homolysis (chemistry)|homolyzes]] to generate sulfate radicals:
: [O<sub>3</sub>SO−OSO<sub>3</sub>]<sup>2−</sup> ⇌ 2 {{chem|SO|4|•−}}
The resulting polymer is terminated with [[sulfate ester]] groups, which can be [[hydrolyzed]] to give OH [[end-group]]s.<ref name=Ullmann>Carlson, D. Peter and Schmiegel, Walter (2000) "Fluoropolymers, Organic" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a11_393}}</ref>

Granular PTFE is produced via [[suspension polymerization]], where PTFE is suspended in an [[Aqueous solution|aqueous]] medium primarily via agitation and sometimes with the use of a [[surfactant]]. PTFE is also synthesized via [[emulsion polymerization]], where a surfactant is the primary means of keeping PTFE in an aqueous medium.<ref>{{cite book |doi=10.1016/B978-1-4557-7442-5.00007-3 |chapter=Manufacturing Polytetrafluoroethylene |title=Introduction to Fluoropolymers |date=2013 |pages=91–124 |isbn=978-1-4557-7442-5 }}</ref> Surfactants in the past have included [[perfluorooctanoic acid]] (PFOA) and [[perfluorooctanesulfonic acid]] (PFOS). More recently, Perfluoro 3,6 dioxaoctanoic acid (PFO2OA) and [[FRD-903]] (GenX) are being used as alternatives.<ref>{{cite journal |last1=Pierozan |first1=Paula |last2=Cattani |first2=Daiane |last3=Karlsson |first3=Oskar |title=Tumorigenic activity of alternative per- and polyfluoroalkyl substances (PFAS): Mechanistic in vitro studies |journal=Science of the Total Environment |date=February 2022 |volume=808 |pages=151945 |doi=10.1016/j.scitotenv.2021.151945 |pmid=34843762 |bibcode=2022ScTEn.80851945P |s2cid=244730906 |doi-access=free }}</ref>

== Properties ==
[[File:Blintzes in frying pan.jpg|thumb|right|PTFE is often used to coat [[non-stick pans]] as it is [[hydrophobic]] and possesses fairly high heat resistance.]]

PTFE is a [[thermoplastic]] [[polymer]], which is a white solid at room temperature, with a density of about 2200&nbsp;kg/m<sup>3</sup> and a melting point of {{convert|600|K}}.<ref name=chemours>{{cite web |title=Fluoroplastic Comparison - Typical Properties |url=https://www.chemours.com/Teflon_Industrial/en_US/tech_info/techinfo_compare.html |website=Chemours |archive-url= https://web.archive.org/web/20160203093128/https://www.chemours.com/Teflon_Industrial/en_US/tech_info/techinfo_compare.html |archive-date=3 February 2016 |url-status=dead}}</ref> It maintains high strength, toughness and self-lubrication at low temperatures down to {{convert|5|K|sigfig=4}}, and good flexibility at temperatures above {{convert|194|K|sigfig=4}}.<ref name=ptfe_handbook>[http://www.rjchase.com/ptfe_handbook.pdf Teflon PTFE Properties Handbook]. Retrieved 11 October 2012.</ref> PTFE gains its properties from the aggregate effect of [[carbon-fluorine bond]]s, as do all fluorocarbons. The only chemicals known to affect these carbon-fluorine bonds are highly reactive metals like the [[alkali metal]]s, at higher temperatures such metals as aluminium and magnesium, and fluorinating agents such as [[xenon difluoride]] and [[cobalt(III) fluoride]].<ref>{{cite web|url=https://plastechcoatings.com/chemours-teflon/|title= Chemours Teflon™ Coating Applications |website=plastechcoatings.com}}</ref> At temperatures above {{Convert|650|–|700|C|F|-1}} PTFE undergoes depolymerization.<ref>{{cite journal |author1=R. J. Hunadi |author2=K. Baum |title=Tetrafluoroethylene: A Convenient Laboratory Preparation |journal=Synthesis |year=1982 |volume=39 |issue=6 |page=454 |doi=10.1055/s-1982-29830|s2cid=96276938 }}</ref> However, it begins to decompose at about {{convert|260|C|}} through {{convert|350|C}}, and [[pyrolysis]] occurs at temperatures above {{Convert|400|C|F|abbr=on}}.<ref name=":3" />

{| class="wikitable"
|-
! Property
! Value
|-
| [[Glass transition temperature|Glass temperature]]
| {{Convert|114.85|C|F K}}<ref>{{cite book |last1=Nicholson |first1=John W. |title=The Chemistry of Polymers |date=2012 |publisher=Royal Society of Chemistry |isbn=978-1-84973-391-5 |page=50 |url=https://books.google.com/books?id=5XFsT69cX_YC&pg=PA50 }}</ref>
|-
| [[Thermal expansion]]
| 112–125×10<sup>−6</sup>&nbsp;K<sup>−1</sup><ref>{{cite web |url=http://www.engineershandbook.com/Tables/plasticthermalexp.htm |title=Reference Tables – Thermal Expansion Coefficients – Plastics |work=engineershandbook.com |access-date=2 January 2012 |archive-date=3 January 2012 |archive-url=https://web.archive.org/web/20120103183144/http://engineershandbook.com/Tables/plasticthermalexp.htm |url-status=dead }}</ref>
|-
| [[Thermal diffusivity]]
| 0.124&nbsp;mm{{sup|2}}/s<ref>{{cite journal |author1=Blumm, J. |author2=Lindemann, A. |author3=Meyer, M. |author4=Strasser, C. | title=Characterization of PTFE Using Advanced Thermal Analysis Technique |journal=[[International Journal of Thermophysics]]| volume=40 |issue=3–4 |page=311 | year=2011 |doi= 10.1007/s10765-008-0512-z |bibcode=2010IJT....31.1919B |s2cid=122020437 }}</ref>
|-
| [[Young's modulus]]
| 0.5&nbsp;GPa
|-
| [[Yield strength]]
| 23&nbsp;MPa
|-
| [[Coefficient of friction]]
| 0.05–0.10
|-
| [[Dielectric constant]]
| {{nowrap|ε {{=}} 2.1}}, {{nowrap|[[dissipation factor|tan(δ)]] < 5×10{{sup|−2}}}}
|-
| Dielectric constant (60&nbsp;Hz)
| {{nowrap|ε {{=}} 2.1}}, {{nowrap|[[dissipation factor|tan(δ)]] < 2×10{{sup|−2}}}}
|-
| [[Dielectric strength]] (1&nbsp;MHz)
| 60&nbsp;MV/m
|-
| [[Magnetic susceptibility]] (SI, 22&nbsp;°C)
| −10.28×10<sup>−6</sup><ref>{{cite journal |last1=Wapler |first1=M. C. |last2=Leupold |first2=J. |last3=Dragonu |first3=I. |last4=von Elverfeldt |first4=D. |last5=Zaitsev |first5=M. |last6=Wallrabe |first6=U. |title=Magnetic properties of materials for MR engineering, micro-MR and beyond |journal=JMR |date=2014 |volume=242 |pages=233–242 |doi=10.1016/j.jmr.2014.02.005 |arxiv=1403.4760 |bibcode=2014JMagR.242..233W |pmid=24705364|s2cid=11545416 }}</ref>
|}

The [[coefficient of friction]] of plastics is usually measured against polished steel.<ref>[http://www.matweb.com/reference/coefficient-of-friction.asp Coefficient of Friction (COF) Testing of Plastics]. MatWeb Material Property Data. Retrieved 1 January 2007.</ref> PTFE's coefficient of friction is 0.05 to 0.10,<ref name=chemours/> which is the third-lowest of any known solid material ([[aluminium magnesium boride]] (BAM) being the lowest, with a coefficient of friction of 0.02; [[diamond-like carbon]] being second-lowest at 0.05).{{cn|date=October 2024}} PTFE's resistance to [[van der Waals force]]s means that it is the only known surface to which a [[gecko]] cannot stick.<ref name="gecko">"[https://web.archive.org/web/20071014063923/http://socrates.berkeley.edu/~peattiea/research_main.html Research into Gecko Adhesion]",{{self-published inline|date=October 2024}} ''[[University of California, Berkeley|Berkeley]]'', 2007-10-14. Retrieved 8 April 2010.</ref> In addition, PTFE can be used to prevent insects from climbing up surfaces painted with the material. For example, PTFE is used to prevent ants from climbing out of [[formicarium|formicaria]]. There are [[Surface treatment of PTFE|surface treatments for PTFE]] that alter the surface to allow adhesion to other materials.

Because of its chemical and thermal properties, PTFE is often used as a gasket material within industries that require resistance to aggressive chemicals such as pharmaceuticals or chemical processing.<ref>{{cite web |url=http://www.gasketresources.com/ptfe-gaskets |title=PTFE Sheet |website=Gasket Resources Inc. |access-date=2017-08-16}}</ref> However, until the 1990s,<ref name="autogenerated655"/> PTFE was not known to crosslink like an [[elastomer]], due to its chemical inertness. Therefore, it has no "memory" and is subject to [[creep (deformation)|creep]]. Because of the propensity to creep, the long-term performance of such seals is worse than for elastomers that exhibit zero, or near-zero, levels of creep. In critical applications, [[Belleville washer]]s are often used to apply continuous force to PTFE gaskets, thereby ensuring a minimal loss of performance over the lifetime of the gasket.<ref>{{cite web |url=https://go.solonmfg.com/l/152611/2016-06-22/mlzyt/152611/15210/Using_Belleville_Springs_to_Maintain_Bolt_Preload.pdf |title=Using Belleville Springs To Maintain Bolt Preload |last=Davet |first=George P. |publisher=Solon Manufacturing Company }}</ref>

PTFE is an [[ultraviolet]] (UV) transparent polymer. However, when exposed to an [[excimer laser]] beam it severely degrades due to heterogeneous [[photothermal effect]].<ref>{{cite journal |last1=Ferry |first1=Laurent |last2=Vigier |first2=Gérard |last3=Bessede |first3=Jean Luc |title=Effect of Ultraviolet Radiation on Polytetrafluoroethylene: Morphology Influence |journal=Polymers for Advanced Technologies |date=May 1996 |volume=7 |issue=5–6 |pages=493–500 |doi=10.1002/(SICI)1099-1581(199605)7:5/6<493::AID-PAT536>3.0.CO;2-D }}</ref>

== Processing ==
Processing PTFE can be difficult and expensive because its high melting temperature, {{convert|327|C}}, is above its decomposition temperature. Even when molten, PTFE does not flow due to its exceedingly high melt-viscosity.<ref>{{cite web|url=http://www.cowie.com/thermal.htm|title=Cowie Technology – PTFE: High Thermal Stability|website=Cowie.com|access-date=2017-08-16}}</ref><ref>{{cite web|url=http://www.inoflon.com/pdf/PG_Free%20flow%20granular%20PTFE.pdf|title=Free Flow Granular PTFE|date=2017-08-16|website=Inoflon Fluoropolymers}}</ref> The viscosity and melting point can be decreased by inclusion of small amount of [[comonomer]]s such as perfluoro (propylvinyl ether) and [[hexafluoropropylene]] (HFP). These cause the otherwise perfectly linear PTFE chain to become branched, reducing its crystallinity.<ref name="Ebnesajjad2016">{{cite book |doi=10.1016/C2009-0-61247-2 |pages=31–32 |title=Expanded PTFE Applications Handbook |date=2017 |isbn=978-1-4377-7855-7 |first1=Sina |last1=Ebnesajjad }}</ref>

Some PTFE parts are made by cold-moulding, a form of [[compression molding]].<ref name=":1">{{cite web|url=http://www.daikinchem.de/downloads/PTFE-M.pdf|title=Polyflon PTFE Molding Powder|date=2017-08-16|website=Daikin Chemical}}</ref> Here, fine powdered PTFE is forced into a mould under high pressure (10–100 MPa).<ref name=":1" /> After a settling period, lasting from minutes to days, the mould is heated at {{convert|360 to 380|C}},<ref name=":1" /> allowing the fine particles to fuse ([[sintering|sinter]]) into a single mass.<ref>{{cite web |title=Unraveling Polymers: PTFE |publisher=Poly Fouoro Ltd. |date=26 April 2011 |url=http://polyfluoroltd.blogspot.com/2011/04/ptfe-myths-busted.html |access-date=23 April 2017}}</ref>

== Applications and uses ==
{{more citations needed section|date=May 2017}}
[[File:Gore twisted pair cable, Passenger Experience Week 2018, Hamburg (1X7A3731) (cropped).jpg|thumb|upright|PTFE-jacketed (white) shielded [[twisted-pair cable]]s]]

=== Wire insulation, electronics ===
The most common use of PTFE, consuming about 50% of production,<ref name="vedantu2024">{{Cite web |title=Polytetrafluoroethylene - Introduction, Production, Applications, and FAQs |url=https://www.vedantu.com/chemistry/polytetrafluoroethylene |access-date=2024-04-01 |website=VEDANTU |language=en}}</ref> is for the insulation of wiring in aerospace and computer applications (e.g. hookup wire, coaxial cables).<ref>{{Cite web |last=Sack |first=Harald |date=2022-06-26 |title=Roy J. Plunkett and the Discovery of Teflon {{!}} SciHi Blog |url=http://scihi.org/roy-j-plunkett-teflon/ |access-date=2024-04-01 |language=en-US}}</ref><ref name="vedantu2024" /> This application exploits the fact that PTFE has excellent [[dielectric]] properties, specifically low [[group velocity dispersion]],<ref name="MishraYagci">{{cite book |editor1-last=Mishra |editor1-first=Munmaya |editor2-last=Yagci |editor2-first=Yusuf |title=Handbook of Vinyl Polymers: Radical Polymerization, Process, and Technology, Second Edition |date=2008 |publisher=CRC Press |isbn=978-0-8247-2595-2 |page=574 |url=https://books.google.com/books?id=CoFE-itPBPgC&pg=PA574 }}</ref> especially at high [[radio frequency|radio frequencies]],<ref name="MishraYagci" /> making it suitable for use as an excellent [[Electrical insulation|insulator]] in [[electrical connector|connector]] assemblies and [[Electrical cable|cable]]s, and in [[printed circuit board]]s used at [[microwave]] frequencies. Combined with its high melting temperature, this makes PTFE the material of choice as a high-performance substitute for the weaker, higher dispersion and lower-melting-point [[polyethylene]] commonly used in low-cost applications.

=== Bearings seals ===
In industrial applications, owing to its low friction, PTFE is used for [[plain bearing]]s, [[gear]]s, [[slide plate]]s, seals, gaskets, bushings,<ref>{{cite web|url=https://www.espemfg.com/teflon-machining-fabrication.html|title=Teflon Machining & Fabrication |website=Espemfg.com|access-date=2018-08-28}}</ref> and more applications with sliding action of parts, where it outperforms [[polyoxymethylene|acetal]] and [[nylon]].<ref>{{cite book |editor1-last=Mishra |editor1-first=Munmaya |editor2-last=Yagci |editor2-first=Yusuf |title=Handbook of Vinyl Polymers: Radical Polymerization, Process, and Technology, Second Edition |date=2008 |publisher=CRC Press |isbn=978-0-8247-2595-2 |page=573 |url=https://books.google.com/books?id=CoFE-itPBPgC&pg=PA573 }}</ref>

=== Electrets ===
Its extremely high bulk [[resistivity]] makes it an ideal material for fabricating long-life [[electret]]s, the [[electrostatic]] analogues of [[magnet|permanent magnets]].

=== Composites ===
PTFE film is also widely used in the production of carbon fiber composites as well as fiberglass composites, notably in the aerospace industry. PTFE film is used as a barrier between the carbon or fiberglass part being built and, in breather and bagging materials, is used to incapsulate the bondment when debulking (vacuum removal of air from between layers of laid-up plies of material) and when curing the composite, usually in an autoclave. The PTFE, used here as a film, prevents the non-production materials from sticking to the part being built, which is sticky due to the carbon-graphite or fiberglass plies being pre-pregnated with [[bismaleimide]] resin. Non-production materials such as Teflon, Airweave Breather, and the bag itself would be considered F.O.D. (foreign object debris/damage) if left in layup.

[[Gore-Tex]] is a brand of expanded PTFE (ePTFE), a material incorporating a fluoropolymer membrane with micropores. The roof of the [[Hubert H. Humphrey Metrodome]] in [[Minneapolis]], US, was one of the largest applications of PTFE coatings. {{convert|20|acre|m2}} of the material was used in the creation of the white double-layered PTFE-coated fiberglass dome.

=== Chemically inert liners ===
Because of its extreme non-reactivity and high temperature rating, PTFE is often used as the liner in [[hose]] assemblies, [[expansion joint#Pipe expansion joints|expansion joint]]s, and in industrial pipe lines, particularly in applications using acids, alkalis, or other chemicals. Its frictionless qualities allow improved flow of highly viscous liquids and for uses in applications such as brake hoses.

=== Tensioned membrane structures ===
PTFE architectural membranes are created by coating a woven glass-fibre base cloth with PTFE, forming one of the strongest and most durable materials used in [[tensile structure]]s.<ref>{{Cite web |title=PTFE |url=https://www.makmax.com.au/fabrics/ptfe/ |website=MakMax Australia}}</ref> Some notable structures featuring PTFE-tensioned membranes include [[The O2 Arena]] in London, [[Moses Mabhida Stadium]] in South Africa, [[Metropolitano Stadium]] in Spain and the [[Sydney Football Stadium (2022)|Sydney Football Stadium]] Roof in Australia.<ref>{{Cite web |date=2022-08-16 |title=Sydney Football Stadium Roof |url=https://www.makmax.com.au/project/sydney-football-stadium-roof/ |access-date=2024-07-21 |website=MakMax Australia |language=en-AU}}</ref>

=== Musical instruments ===
PTFE is often found in musical instrument lubrication products, most commonly valve oil.
=== Lubricants ===
PTFE is used in some aerosol lubricant sprays, including in [[Micronization|micronized]] and polarized form. It is notable for its extremely low coefficient of friction, its hydrophobia (which serves to inhibit rust), and for the dry film it forms after application, which allows it to resist collecting particles that might otherwise form an abrasive paste.<ref>{{Cite news|url=https://interflonusa.com/what-is-micpol/#assembly|title=What is MicPol?|website=Interflonusa.com|access-date=2018-10-03|language=en|archive-date=3 October 2018|archive-url=https://web.archive.org/web/20181003141443/https://interflonusa.com/what-is-micpol/#assembly|url-status=dead}}</ref> Brands include GT85, Tri-Flow and WD-40 Specialist.<ref>{{Cite web|url=https://www.baysidemarine.co.uk/gt85-general-lubricant-with-ptfe---400ml-6284-p.asp|title=GT85 General Lubricant with PTFE - 400ml|website=Baysidemarine.co.uk|access-date=5 March 2022}}</ref><ref>{{Cite web |title=Tri-Flow Superior Lubricant Aerosol – Triflow Lubricants |url=https://www.triflowlubricants.com/product/tri-flow-superior-lubricant-aerosol/ |access-date=2024-10-30 |language=en}}</ref><ref>{{Cite web |title=Dry Lube PTFE Spray - Dirt & Dust Resistant Dry Lube {{!}} WD-40 |url=https://www.wd40.com/products/dry-lube/ |access-date=2024-10-30 |website=www.wd40.com}}</ref>

=== Kitchenware ===
[[File:Teflon-jar hg.jpg|alt=Two teflon jars|thumb|Two molded PTFE jars.]]
PTFE is best known for its use in [[Non-stick surface|coating non-stick]] [[frying pan]]s and other cookware, as it is [[hydrophobic]] and possesses fairly high heat resistance.

The sole plates of some [[Clothes iron|clothes irons]] are coated with PTFE.<ref>[http://pratique.leparisien.fr/fiches-pratiques/electromenager/repassage/fers-a-repasser-semelle-teflon-1600004600043011#xtref=https%253A%252F%252Fwww.google.fr%252F Fers à repasser semelle teflon - Fiche pratique - Le Parisien]. {{Webarchive|url=https://web.archive.org/web/20160816072735/http://pratique.leparisien.fr/fiches-pratiques/electromenager/repassage/fers-a-repasser-semelle-teflon-1600004600043011#xtref=https%253A%252F%252Fwww.google.fr%252F |date=16 August 2016 }} Pratique.leparisien.fr. Retrieved on 2016-11-17.</ref>


=== Others ===
{{trivia|section|date=August 2023}}
[[File:PTFE tapes with pressure-sensitive adhesive backing, rolls of 15 and 25 mm widths.jpg|thumb|right|PTFE tapes with pressure-sensitive adhesive backing]]Other niche applications include:
* It is often found in [[ski binding]]s as a non-mechanical AFD (anti-friction device) 
* It can be stretched to contain small pores of varying sizes and is then placed between fabric layers to make a waterproof, breathable fabric in outdoor apparel.<ref name="gore">{{cite web|url=https://www.infinitymotorcycles.com/news/a-motorcyclists-guide-to-gore-tex/119|title=A Motorcyclist's Guide To Gore-Tex|publisher=Infinity Motorcycles|access-date=17 January 2019|archive-url=https://web.archive.org/web/20150705134857/https://www.infinitymotorcycles.com/news/a-motorcyclists-guide-to-gore-tex/119|archive-date=5 July 2015|url-status=dead}}</ref>
* It is used widely as a fabric protector to repel stains on formal school-wear, like uniform blazers.<ref name=CutterAndTailor>{{cite web|url=http://www.cutterandtailor.com/forum/index.php?showtopic=852|title=Advantages and Disadvantages of Teflon-coated Covert Cloth|work=The Cutter and Tailor|access-date=22 May 2015|archive-date=3 July 2015|archive-url=https://web.archive.org/web/20150703221827/http://www.cutterandtailor.com/forum/index.php?showtopic=852|url-status=dead}}</ref>
* It is frequently used as a lubricant to prevent captive insects and other [[arthropod]]s from escaping.
* It is used as a coating for medical and healthcare applications formulated to provide strength and heat resistance to surgical devices and other medical equipment.<ref name=DeltaCoatingsandLinings>{{Cite web|url=https://www.deltacoatingsandliningsbr.com/ptfe|title=PTFE & Industrial Non-Stick Fluoropolymer Coating Services &#124; Delta Coatings & Linings, Inc.|website=Deltacoatingsandliningsbr.com|access-date=5 March 2022}}</ref> 
* It is used as a film interface patch for sports and medical applications, featuring a pressure-sensitive adhesive backing, which is installed in strategic high friction areas of footwear, insoles, [[ankle-foot orthosis]], and other medical devices to prevent and relieve friction-induced blisters, calluses and foot ulceration.<ref name=FilmInterfacePatch>{{cite web |url=http://www.oandp.org/jpo/library/popup.asp?xmlpage=2006_04_093&type=image&id=f11 |title=Film Interface Patch |publisher=American Academy of Orthotists & Prosthetists}}</ref>
* Expanded PTFE membranes have been used in trials to assist [[trabeculectomy]] surgery to treat glaucoma.<ref>{{cite journal |last1=Park |first1=Junghyun |last2=Rittiphairoj |first2=Thanitsara |last3=Wang |first3=Xue |last4=E |first4=Jian-Yu |last5=Bicket |first5=Amanda K |title=Device-modified trabeculectomy for glaucoma |journal=Cochrane Database of Systematic Reviews |date=13 March 2023 |volume=2023 |issue=3 |pages=CD010472 |doi=10.1002/14651858.CD010472.pub3 |pmc=10010250 |pmid=36912740 }}</ref>
* Powdered PTFE is used in [[pyrotechnic composition]]s as an [[oxidizer]] with powdered metals such as [[aluminium]] and [[magnesium]]. Upon ignition, these mixtures form carbonaceous [[soot]] and the corresponding metal [[fluoride]], and release large amounts of heat. They are used in [[infrared decoy flare]]s and as [[igniter]]s for [[solid-fuel rocket]] [[propellant]]s.<ref name=koch>{{cite journal |last1=Koch |first1=Ernst-Christian |title=Metal-Fluorocarbon-Pyrolants: III. Development and Application of Magnesium/Teflon/Viton (MTV) |journal=Propellants, Explosives, Pyrotechnics |date=November 2002 |volume=27 |issue=5 |pages=262–266 |doi=10.1002/1521-4087(200211)27:5<262::AID-PREP262>3.0.CO;2-8 }}</ref> Aluminium and PTFE is also used in some [[thermobaric]] fuel compositions.
* Powdered PTFE is used in a suspension with a low-viscosity, azeotropic mixture of siloxane ethers to create a lubricant for use in [[twisty puzzle]]s.<ref>{{cite web|url=https://thecubicle.us/lubicle-p-9146.html|title=Lubicle 1|website=TheCubicle.us|language=en|access-date=2017-05-20}}</ref>
* In optical [[radiometry]], sheets of PTFE are used as measuring heads in spectroradiometers and broadband radiometers (e.g., [[illuminance]] meters and [[Ultraviolet|UV]] [[radiometer]]s) due to PTFE's capability to diffuse a transmitting light nearly perfectly. Moreover, optical properties of PTFE stay constant over a wide range of wavelengths, from UV down to near [[infrared]]. In this region, the ratio of its regular transmittance to diffuse transmittance is negligibly small, so light transmitted through a [[diffuser (optics)|diffuser]] (PTFE sheet) radiates like [[Lambert's cosine law]]. Thus PTFE enables cosinusoidal angular response for a detector measuring the power of optical radiation at a surface, e.g. in solar [[irradiance]] measurements.
* [[Teflon-coated bullet]]s are coated with PTFE to reduce wear on the [[rifling]] of firearms that uncoated projectiles would cause. PTFE itself does not give a projectile an armor-piercing property.<ref>{{cite journal|url=http://www.guncite.com/ktwint.html|title=Interview with an inventor of the KTW bullet|journal=NRAction Newsletter|volume =4|issue =5 |date=May 1990}}</ref>
* Its high corrosion resistance makes PTFE useful in laboratory environments, where it is used for lining containers, as a coating for magnetic stirrers, and as tubing for highly corrosive chemicals such as [[hydrofluoric acid]], which will dissolve glass containers. It is used in containers for storing [[fluoroantimonic acid]], a [[superacid]].<ref>{{cite web |url=http://www.realclearscience.com/blog/2013/08/the-worlds-strongest-acids.html |title=The World's Strongest Acids: Like Fire and Ice |last=Pomeroy |first=Ross |date=2013-08-24 |access-date=2016-04-09 }}</ref>
* PTFE tubes are used in gas-gas heat exchangers in gas cleaning of waste incinerators. Unit power capacity is typically several megawatts.
* PTFE is widely used as a [[thread seal tape]] in plumbing applications, largely replacing paste thread dope.
* PTFE membrane filters are among the most efficient industrial air filters. PTFE-coated filters are often used in [[dust collection system]]s to collect [[aerosol|particulate matter]] from air streams in applications involving high temperatures and high particulate loads such as coal-fired power plants, cement production and steel foundries.<ref>{{cite web|url=http://www.baghouse.com/2012/05/28/industrial-air-permits-new-clean-air-regulations-and-baghouses/|title=Industrial Air Permits - New Clean Air Regulations And Baghouses|date=28 May 2012|publisher=Baghouse.com}}</ref> 
* PTFE grafts can be used to bypass [[stenosis|stenotic]] [[artery|arteries]] in peripheral vascular disease if a suitable autologous [[vein]] graft is not available.
* Many bicycle lubricants and greases contain PTFE and are used on [[bicycle chain|chains]] and other moving parts subjected to frictional forces (such as [[Bicycle wheel#Bearings|hub bearings]]).
* PTFE is used for some types of [[dental floss]].
* PTFE can also be used when placing [[dental fillings]], to isolate the contacts of the adjacent tooth so the restorative materials will not stick to the adjacent tooth.<ref>{{cite journal|url=http://www.dentistrytoday.com/restorative-134/1864--sp-1460991174|title=Using Plumber's Teflon Tape to Enhance Bonding Procedures|first=Dennis E. | last=Brown, DDS|journal=Dentistry Today|date=January 2002 |volume=21 |issue=1 |pages=76–8, 80–1 |pmid=11824121 }}</ref><ref>{{cite journal|title=Polytetrafluoroethylene (PTFE) tape as a matrix in operative dentistry.|last=Dunn|first=WJ|display-authors=etal|journal=Operative Dentistry|pmid=15279489|volume=29|pages=470–2|year=2004|issue=4}}</ref>
* PTFE sheets are used in the production of [[butane hash oil]] due to its non-stick properties and resistance to non-polar solvents.<ref>{{cite book |title=Beyond Buds |first=Ed |last=Rosenthal |publisher=Quick American Archives |edition=Revised |date=21 October 2014 |isbn=978-1936807239}}</ref>
* PTFE, associated with a slightly textured laminate, makes the plain bearing system of a [[Dobsonian telescope]].
* PTFE is widely used as a non-stick coating for food processing equipment;<ref name = surface/> dough hoppers, mixing bowls, conveyor systems, rollers, and chutes. PTFE can also be reinforced where abrasion is present – for equipment processing seeded or grainy dough for example.<ref name = surface>{{Cite news|url=http://www.surfacetechnology.co.uk/surface-coatings/fluoropolymer-coating/ |title= Fluoropolymer PTFE coating services from Surface Technology UK|work=Surface Technology|access-date=2018-02-26|language=en-US}}</ref>
* PTFE has been experimented with for [[electroless nickel plating]].
* PTFE tubing is used for Bowden tubing in [[3D printing|3D printers]] because its low friction allows the extruder stepper motor to push filament through it more easily.
* PTFE is commonly used in aftermarket add-on mouse feet for [[gaming mice]] to reduce friction of the mouse against the mouse pad, resulting in a smoother glide.
* PTFE foils are commonly used with laserprinters everywhere, in their fuser unit, wrapped around the heater element(s) and as well on the opposite pressure roller to prevent any kind of sticking to it (neither the printed paper nor toner waste)
* PTFE is also used to make body jewellery as it's much safer to wear compared to materials like acrylic, that release toxics into the body at 26.6&nbsp;°C, unlike PTFE at 650–700&nbsp;°C.
* PTFE is used to make bookbinding tools for folding, scoring and separating sheets of paper. These are typically referred to as Teflon bone folders.
* PTFE is commonly used for the tip of [[Desoldering#Pumps|desoldering pumps]] due to its high melting temperature.

== Safety ==
While PTFE is stable at lower temperatures, it begins to deteriorate at temperatures of about {{convert|260|C}}, it decomposes above {{convert|350|C}}, and [[pyrolysis]] occurs at temperatures above {{Convert|400|C|F|abbr=on}}.<ref name=":3">{{cite journal |last1=Sajid |first1=Muhammad |last2=Ilyas |first2=Muhammad |title=PTFE-coated non-stick cookware and toxicity concerns: a perspective |journal=Environmental Science and Pollution Research |date=October 2017 |volume=24 |issue=30 |pages=23436–23440 |doi=10.1007/s11356-017-0095-y |pmid=28913736 |bibcode=2017ESPR...2423436S }}</ref> The main decomposition products are [[fluorocarbon]] gases and a [[Sublimation (phase transition)|sublimate]], including [[tetrafluoroethylene]] (TFE) and [[difluorocarbene]] [[Radical (chemistry)|radicals]] (RCF2).<ref name=":3" />

An animal study conducted in 1955 concluded that it is unlikely that these products would be generated in amounts significant to health at temperatures below {{convert|250|C}}.<ref name="zapp">{{cite journal |vauthors=Zapp JA, Limperos G, Brinker KC |title= Toxicity of pyrolysis products of 'Teflon' tetrafluoroethylene resin |journal= Proceedings of the American Industrial Hygiene Association Annual Meeting |date=26 April 1955}}</ref> Above those temperatures the degradation by-products can be lethal to [[bird]]s,<ref>{{cite news|publisher=DuPont|title=Key Safety Questions About Teflon Nonstick Coatings|url=http://www2.dupont.com/Teflon/en_US/products/safety/key_questions.html#q6|access-date=28 November 2014|archive-date=2 May 2013|archive-url=https://web.archive.org/web/20130502210638/http://www2.dupont.com/Teflon/en_US/products/safety/key_questions.html#q6|url-status=dead}}</ref> and can cause [[flu-like symptoms]] in humans ([[polymer fume fever]]),<ref>{{cite web|publisher=DuPont|url=http://www2.dupont.com/Teflon/en_US/products/safety/key_questions.html#q5|title=Key Safety Questions about the Safety of Nonstick Cookware|access-date=28 November 2014|archive-date=2 May 2013|archive-url=https://web.archive.org/web/20130502210638/http://www2.dupont.com/Teflon/en_US/products/safety/key_questions.html#q5|url-status=dead}}</ref> although in humans those symptoms disappear within a day or two of being moved to fresh air.<ref name=hsdb />

Most cases of polymer fume fever in humans occur due to smoking PTFE-contaminated tobacco,<ref name=hsdb /> although cases have occurred in people who have [[welding|welded]] near PTFE components.<ref name=hsdb /> PTFE-coated cookware is unlikely to reach dangerous temperatures with normal use, as meat is usually fried between {{convert|204 and 232|C}}, and most [[cooking oil]]s (except refined [[safflower oil|safflower]] and [[avocado oil|avocado]] oils) start to [[smoke point|smoke]] before a temperature of {{convert|260|C|F}} is reached. A 1973 study by DuPont's Haskell Laboratory found that a 4-hour exposure to the fumes emitted by PTFE cookware heated to {{convert|280|C}} was lethal for [[parakeets]], although that was a higher temperature than the {{convert|260|C|F}} required for fumes from pyrolyzed butter to be lethal to the birds.<ref>{{cite journal |last1=Griffith |first1=Franklin D. |last2=Stephens |first2=Susan S. |last3=Tayfun |first3=Figen O. |title=Exposure of Japanese Quail and Parakeets to the Pyrolysis Products of Fry Pans Coated with Teflon® and Common Cooking Oils |journal=American Industrial Hygiene Association Journal |date=April 1973 |volume=34 |issue=4 |pages=176–178 |doi=10.1080/0002889738506828|pmid=4723395 }}</ref>

[[Perfluorooctanoic acid]] (PFOA), a chemical formerly used in the manufacture of PTFE products such as non-stick coated cookware, can be [[carcinogen]]ic for people who are exposed to it (see [[#Ecotoxicity|Ecotoxicity]]).<ref name=cancer>{{cite web |title=Perfluorooctanoic Acid (PFOA), Teflon, and Related Chemicals |url=https://www.cancer.org/cancer/cancer-causes/teflon-and-perfluorooctanoic-acid-pfoa.html |website=www.cancer.org |access-date=4 April 2022 |language=en}}</ref> Concerning levels of PFOA have been found in the blood of people who work in or live near factories where the chemical is used, and in people regularly exposed to PFOA-containing products such as some [[ski wax]]es and stain-resistant fabric coatings, but non-stick cookware was not found to be a major source of exposure, as the PFOA is burned off during the manufacturing process and not present in the finished product.<ref name=hsdb /> Non-stick coated cookware has not been manufactured using PFOA since 2013,<ref>{{cite web|title=The truth about teflon: are non-stick pans safe?|url=https://www.bhg.com.au/the-truth-about-teflon-are-non-stick-pans-safe|access-date=2020-06-11|website=Better Homes and Gardens|date=2 October 2019 |language=en-us}}</ref> and PFOA is no longer being made in the United States.<ref name=cancer />

== Ecotoxicity ==
===Living Building Challenge===
PTFE was added to the [[Red List building materials|Living Building Challenge (LBC) Red List]] in 2016. The Red List bans substances prevalent in the building industry that pose serious risks to human health and the environment from construction that seeks to meet the criteria of the Living Building Challenge (LBC).<ref>{{cite web |title=LBC Red List CASRN Guide 2024 |url=https://living-future.org/wp-content/uploads/2024/04/LBC-Red-List-CASRN-Guide-2024.xlsx |publisher=International Living Future Institute |access-date=5 November 2024}}</ref>

=== Trifluoroacetate ===
[[Sodium trifluoroacetate]] and the similar compound [[sodium chlorodifluoroacetate]] can both be generated when PTFE undergoes [[Thermal decomposition|thermolysis]], as well as producing longer chain polyfluoro- and/or polychlorofluoro- (C3-C14) carboxylic acids which may be equally persistent. These products can accumulate in evaporative [[wetland]]s and have been found in the roots and seeds of wetland plant species, but has not been observed to have an adverse impact on plant health or germination success.<ref name=hsdb>{{cite web |title=Teflon |work=Hazardous Substances Data Bank |url=https://pubchem.ncbi.nlm.nih.gov/source/hsdb/833 |publisher=National Center for Biotechnology Information National Library of Medicine }}</ref>

=== PFOA ===
{{Main|Perfluorooctanoic acid}}
Perfluorooctanoic acid (PFOA, or C8) has been used as a [[surfactant]] in the [[emulsion polymerization]] of PTFE, although several manufacturers have entirely discontinued its use.

PFOA persists indefinitely in the environment.<ref>{{cite report|date = March 2014|title = Emerging Contaminants Fact Sheet &ndash; Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) |url = https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100LTG6.txt|website = National Service Center for Environmental Publications|publisher = [[United States Environmental Protection Agency]] |id = 505-F-14-001 |access-date = 10 February 2019|page = 1}}</ref> PFOA has been detected in the blood of many individuals of the general US population in the low and sub-[[parts per billion]] range, and levels are higher in chemical plant employees and surrounding subpopulations. PFOA and [[perfluorooctanesulfonic acid]] (PFOS) have been estimated to be in every American person's blood stream in the parts per billion range, though those concentrations have decreased by 70% for PFOA and 84% for PFOS between 1999 and 2014, which coincides with the end of the production and phase out of PFOA and PFOS in the US.<ref>{{cite web|url=https://casaweb.org/wp-content/uploads/2020/01/National-PFAS-Receivers-Factsheet.pdf|title=PFAs Factsheet|website=Casaweb.org|access-date=5 March 2022}}</ref> The general population has been exposed to PFOA through massive dumping of C8 waste into the ocean and near the [[Ohio River]] Valley.<ref name="NYTmagazine">{{cite news|last1=Rich|first1=Nathaniel |title= The Lawyer Who Became Dupont's Worst Nightmare|url=https://www.nytimes.com/2016/01/10/magazine/the-lawyer-who-became-duponts-worst-nightmare.html|newspaper=The New York Times|date=6 January 2016 |access-date=7 January 2016 |url-access=subscription}}</ref><ref name=Blake>{{cite web|last1=Blake|first1=Mariah|title=Welcome to Beautiful Parkersburg, West Virginia Home to one of the most brazen, deadly corporate gambits in U.S. history.|url=http://highline.huffingtonpost.com/articles/en/welcome-to-beautiful-parkersburg/|website=HuffPost|access-date=31 August 2015}}</ref><ref name="Fellner-16June2018">{{cite news |last1=Fellner |first1=Carrie |title=Toxic Secrets: Professor 'bragged about burying bad science' on 3M chemicals |url=https://www.smh.com.au/lifestyle/health-and-wellness/toxic-secrets-professor-bragged-about-burying-bad-science-on-3m-chemicals-20180615-p4zlsc.html |access-date=25 June 2018 |work=[[The Sydney Morning Herald]]|date=16 June 2018}}</ref> PFOA has been detected in industrial waste, stain-resistant carpets, carpet cleaning liquids, [[house dust]], [[Popcorn bag|microwave popcorn bags]], water, food and PTFE cookware.

As a result of [[Perfluorooctanoic acid#Robert Bilott investigation|a class-action lawsuit and community settlement]] with [[DuPont]], three [[Epidemiology|epidemiologists]] conducted studies on the population of Parkersburg, WV surrounding the (former DuPont) Chemours Washington Works chemical plant that was exposed to PFOA at levels greater than in the general population. The studies concluded that there was an association between PFOA exposure and six health outcomes: [[kidney cancer]], [[testicular cancer]], [[ulcerative colitis]], [[thyroid disease]], [[hypercholesterolemia]] (high cholesterol), and [[gestational hypertension]] (pregnancy-induced high blood pressure).<ref>{{Cite journal | last1 = Nicole | first1 = W. | title = PFOA and Cancer in a Highly Exposed Community: New Findings from the C8 Science Panel | doi = 10.1289/ehp.121-A340 | journal = Environmental Health Perspectives | volume = 121 | issue = 11–12 | pages = A340 | year = 2013 | pmid = 24284021| pmc = 3855507}}</ref>

Overall, PTFE cookware is considered a minor exposure pathway to PFOA.<ref>{{cite journal 
|vauthors=Trudel D, Horowitz L, Wormuth M, Scheringer M, Cousins IT, Hungerbühler K | title=Estimating consumer exposure to PFOS and PFOA 
| journal=Risk Anal. 
| volume=28 |issue=2 |pages=251–69 |date=April 2008 
| pmid=18419647 |doi=10.1111/j.1539-6924.2008.01017.x| bibcode=2008RiskA..28..251T 
| s2cid=10777081 
}}</ref>

=== GenX ===
{{Main|GenX}}
As a result of the lawsuits concerning [[Perfluorooctanoic acid#Robert Bilott investigation|the PFOA class-action lawsuit]], DuPont began to use GenX, a similarly fluorinated compound, as a replacement for perfluorooctanoic acid in the manufacture of [[fluoropolymer]]s, such as Teflon-brand PTFE.<ref>{{cite web |title=Evaluation of substances used in the GenX technology by Chemours, Dordrecht |url=http://www.rivm.nl/dsresource?objectid=3186e480-7d66-4ded-ac59-acd2e804d3b5|date=2016-12-12 |last1=Beekman |first1=M. |last2=Zweers |first2=P. |display-authors=1|access-date=2017-07-23 |publisher=National Institute for Public Health and the Environment ([[RIVM]], The Netherlands)}}</ref><ref>{{cite web |url=https://www.epa.gov/pfas/basic-information-pfas#difference |title=What is the difference between PFOA, PFOS and GenX and other replacement PFAS? |author=<!--Not stated--> |date=2018-02-18 |website=PFOA, PFOS and Other PFASs |publisher=EPA}}</ref> However, the EPA has classified GenX as more toxic than PFOA<ref name="genx-more-toxic" /> and it has proven to be a "regrettable substitute";<ref name="genx-regret">{{Cite journal |last=Ahearn |first=Ashley |date=2019-03-24 |title=A Regrettable Substitute: The Story of GenX |journal=Podcasts: The Researcher's Perspective |volume=2019 |issue=1 |doi=10.1289/EHP5134 |doi-access=free}}</ref> [[GenX#Health Effects|its effects may be equally harmful or even more detrimental]] than those of the chemical it was meant to replace.<ref name="genx-regret" /><ref name="epa-human-genx-toxicicty" />

The chemicals are manufactured by [[Chemours]], a corporate spin-off of DuPont, in [[Fayetteville, North Carolina]].<ref>{{cite web |url=https://files.nc.gov/ncdeq/GenX/SAB/FAQ_updated_021518.pdf |title=GenX Frequently Asked Questions |author=<!--Not stated--> |date=2018-02-15 |website=GenX Investigation |publisher=North Carolina Department of Environmental Quality (NCDEQ) |location=Raleigh, NC}}</ref> Fayetteville Works was the site where DuPont began manufacture of PFOA after the lawsuit in Parkersburg WV halted their production there. When EPA asked companies to voluntarily phase out PFOA production, it was replaced by GenX in Fayetteville Works. In June of 2017, The Wilmington Star-News broke the story<ref>{{cite web | url=https://www.starnewsonline.com/story/news/environment/2017/06/07/toxin-taints-cfpua-drinking-water/20684831007/ | title=Toxin taints CFPUA drinking water }}</ref> that GenX was found in the Cape Fear River – the drinking water supply for 500,000 people. The source of the pollution was determined to be the Fayetteville Works site, which had been run by DuPont since its founding in 1971 and then managed by DuPont spinoff, The Chemours Company, since 2015.  The water utility confirmed they had no ability to filter these chemicals from the drinking water. 

The North Carolina Department of Environmental Quality (NC DEQ) records<ref>{{cite web | url=https://www.deq.nc.gov/genx/fact-sheet-chemours-proposed-consent-order/download | title=FACT SHEET: Proposed Chemours Consent Order | date=21 December 2018 }}</ref> indicate that DuPont started release PFAS into the area beginning in 1976 with the production of Nafion, and that PFAS including GenX had been released as a byproduct of the production of Vinyl Ethers since 1980, exposing the Cape Fear Basin for decades. A small nonprofit called Cape Fear River Watch sued NC DEQ for not taking swifter and stronger action, and sued the polluter, Chemours, for violations of the Clean Water Act and the Toxic Substances Control Act. The result was a Consent Order,<ref>{{cite web | url=https://www.deq.nc.gov/news/key-issues/genx-investigation/chemours-consent-order | title=Chemours Consent Order &#124; NC DEQ }}</ref> signed February 25, 2019 by Cape Fear River Watch, NC DEQ, and Chemours.<ref>{{cite web | url=https://capefearriverwatch.org/genx/ | title=PFAS &#124; Cape Fear River Watch | date=20 September 2019 }}</ref> The order has required Chemours to stop wastewater discharge, air emissions, groundwater discharge, sampling and filtration options to well users, and required sampling that proved there were upwards of 300 distinct PFAS compounds being released from Fayetteville Works.<ref>{{cite web | url=https://www.chemours.com/en/about-chemours/global-reach/fayetteville-works/compliance-testing | title=Consent Order Compliance }}</ref>

== Similar polymers ==
[[File:PFA Structure.svg|thumb|Teflon is also used as the trade name for a polymer with similar properties, [[perfluoroalkoxy polymer resin]] (PFA).]]

The Teflon trade name is also used for other polymers with similar compositions:
* [[Perfluoroalkoxy alkane]] (PFA)
* [[Fluorinated ethylene propylene]] (FEP)

These retain the useful PTFE properties of low friction and nonreactivity, but are also more easily formable. For example, FEP is softer than PTFE and melts at {{convert|533|K}}; it is also highly transparent and resistant to sunlight.<ref>[https://web.archive.org/web/20100724195156/http://www.texloc.com/closet/cl_fep_properties.htm FEP Detailed Properties], Parker-TexLoc, 13 April 2006. Retrieved 10 September 2006.</ref>

== See also ==
* [[BS 4994]], PTFE as a thermoplastic lining for dual laminate chemical process plant equipment
* [[Dark Waters (2019 film)|''Dark Waters'']], a film about litigation related to PFOA
* [[The Devil We Know (film)|''The Devil We Know'']], documentary on PFOA's health and environmental effects
* [[ETFE]]
* [[Gore-Tex]] waterproof fabric
* [[Magnesium/Teflon/Viton]], pyrolant thermite composition
* [[Polymer adsorption]]
* [[Superhydrophobic coating]]
* [[Surface treatment of PTFE]]

== Notes ==
{{notelist}}

== References ==
{{reflist|30em}}

== Further reading ==
* {{Cite journal
| last1 = Ellis
| first1 = D.A.
| last2 = Mabury
| first2 = S.A.
| last3 = Martin
| first3 = J.W.
| last4 = Muir
| first4 = D.C.G. |author5=Mabury, S.A. |author6=Martin, J.W. |author7=Muir, D.C.G.
| year = 2001
| title = Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment
| journal = Nature
| volume = 412
| issue = 6844
| pages = 321–324
| doi = 10.1038/35085548
| pmid = 11460160
| bibcode = 2001Natur.412..321E
| s2cid = 4405763
}}

== External links ==
* [https://web.archive.org/web/20090227022541/http://www.plasmatechsystems.com/about/pubs/Plasma%20Processes%20Polytetrafluoroethylene.pdf Plasma Processes and Adhesive Bonding of Polytetrafluoroethylene]
* [https://web.archive.org/web/20100305090149/http://fluorotherm.com/Properties-PTFE.asp PTFE (polytetrafluoroethylene) (Properties) | Fluorotherm.com]

{{DuPont|state=collapsed}}
{{Plastics}}

{{DEFAULTSORT:Polytetrafluoroethylene}}
[[Category:American inventions]]
[[Category:Biomaterials]]
[[Category:Dielectrics]]
[[Category:Dry lubricants]]
[[Category:DuPont]]
[[Category:DuPont products]]
[[Category:Fluorocarbons]]
[[Category:Fluoropolymers]]
[[Category:Thermoplastics]]
[[Category:Pyrotechnic oxidizers]]
[[Category:Roofing materials]]
[[Category:Engineering plastic]]
[[Category:1938 in science]]