Polytetrafluorethylene (PTFE)

Chandra Heller

Michael Mallicote

Discovery Accidentally discovered on April 6, 1938

by Roy Plunkett.

Uses By 1941, PTFE had been patented and

had its first brand name Teflon®. By 1946, the resin product was being

used to produce machine parts for military and industrial applications.

In the 1960s it began its life in the arena of nonstick cookware.

Uses (continued) Today it has expanded into a whole

family of polymers (resins, films, coatings, moldable forms, powders) and sold under various brand names, including Gore-Tex® and Zylon®.

It is used in a wide range of industries from aerospace to pharmaceuticals and is sold in over 40 countries worldwide.

Teflon® Monomer

C C

F

F

F

F

tetrafluoroethylene

Teflon® Polymer

Teflon® Polymer (continued)

Emulsion Polymerization

Initiation: Free radical formationROOR + Heat → 2 RO

Initiation: Formation of new free radicals by peroxide + TFE in aqueous phaseRO + CF2=CF2 → RO(CF2–CF2)

Propagation:Growth of free radicals by further addition of TFERO(CF2–CF2) + n CF2=CF2 → RO(CF2–CF2)–(CF2–CF2)

Free radicals undergo hydrolysis where a hydroxyl group replaces the peroxideRO(CF2–CF2)–(CF2–CF2) + H2O → HO(CF2–CF2)n–(CF2–CF2) + H+ + HOR

HO(CF2=CF2)n–(CF2=CF2) + H2O → COOHCF2–(CF2–CF2) n + 2HF

Termination:COOH– CF2–(CF2– CF2) n + COOH– CF2–(CF2– CF2) m → COOH– CF2–(CF2– CF2) m+n COOH

Toxicity The monomer TFE is a confirmed animal

carcinogen with unknown relevance to humans.

The finished polymer in solid form is inert under ordinary conditions. There is some indication that the powdered forms of PTFE may be carcinogenic if inhaled.

Recycling of PTFE It is easy to recycle since no chemical

reaction is necessary. Only the extruded forms are recycled (not the

resin or powerdered forms). The uses of recycled PTFE are restricted. It is typically ground up into fine powders and

used as additives in such products as inks, paints, and cosmetics.

Questions

References1) Inventor of the Week: Archive. http://web.mit.edu/invent/iow/plunkett.html (2000)2) Teflon.com - the complete resource on Teflon® products by DuPont. http://

www.teflon.com/NASApp/Teflon/TeflonPageServlet?pageId=/consumer/na/home_page.jsp (2005)3) Biomaterials. http://www.abe.msstate.edu/Classes/abe4523_6523/polymers.PDF (2001)4) Zonyl Packaging: Whistleblower. http://www.mindfully.org/Plastic/Teflon/Zonyl-DuPont-Risk17nov05.htm (2005)5) Teflon fluorocarbon information. http://www.omega.com/techref/fluoro.html (2001)6) Polymers. http://www.chemistry.mtu.edu/pages/courses/ch1120-pcharles/Oxtoby_Ch25.pdf (2004)7) Ebnesajjad, S. Non-melt Processible Fluoroplastics : The Definitive User's Guide and Databook. Norwich, N.Y. :

Plastics Design Library. (2000)8) Ebnesajjad, S. Melt Processible Fluoropolymers: The Definitive User's Guide and Databook. Norwich, N.Y. : Plastics

Design Library (2003)9) Chemical Structure. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/Chemical_Structure.html (2003)10) Synthesis. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/synthesis.html. (2003)11) Burridge, E. PTFE. Eur. Chem. News. 80, 16 (2004)12) Bingham, E., Cohrssen, B., Powell, C., Eds. Patty's Toxicology. New York : John Wiley. (2001)13) Useless Information. http://home.nycap.rr.com/useless/teflon/ (2003)14) DuPont Electronic Materials Keep Mars Rovers Going.

http://www2.dupont.com/Teflon_Industrial/en_US/news_events/article20050120.html (2005)15) National Toxicology Program. http://ntp.niehs.nih.gov/ (2005)16) Learn more about Teflon®. http://www.teflon.com/NASApp/Teflon/TeflonPageServlet?pageId=/consumer/na/eng/

housewares/keyword/teflon_keyword_birds.html (2005)17) NIOSH: The National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/homepage.html (2005)18) Recycling. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/Recycling.html (2003)