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 F F C C F F tetrafluoroethylene
Emulsion Polymerization Initiation: Free radical formation ROOR + Heat → 2 RO Initiation: Formation of new free radicals by peroxide + TFE in aqueous phase RO + CF2=CF2 → RO(CF2–CF2) Propagation: Growth of free radicals by further addition of TFE RO(CF2–CF2) + n CF2=CF2 → RO(CF2–CF2)–(CF2–CF2) Free radicals undergo hydrolysis where a hydroxyl group replaces the peroxide RO(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.
References • Inventor of the Week: Archive. http://web.mit.edu/invent/iow/plunkett.html (2000) • Teflon.com - the complete resource on Teflon® products by DuPont. http://www.teflon.com/NASApp/Teflon/TeflonPageServlet?pageId=/consumer/na/home_page.jsp (2005) • Biomaterials. http://www.abe.msstate.edu/Classes/abe4523_6523/polymers.PDF (2001) • Zonyl Packaging: Whistleblower. http://www.mindfully.org/Plastic/Teflon/Zonyl-DuPont-Risk17nov05.htm (2005) • Teflon fluorocarbon information. http://www.omega.com/techref/fluoro.html (2001) • Polymers. http://www.chemistry.mtu.edu/pages/courses/ch1120-pcharles/Oxtoby_Ch25.pdf (2004) • Ebnesajjad, S. Non-melt Processible Fluoroplastics : The Definitive User's Guide and Databook. Norwich, N.Y. : Plastics Design Library. (2000) • Ebnesajjad, S. Melt Processible Fluoropolymers: The Definitive User's Guide and Databook.Norwich, N.Y. : Plastics Design Library (2003) • Chemical Structure. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/Chemical_Structure.html (2003) • Synthesis. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/synthesis.html. (2003) • Burridge, E. PTFE. Eur. Chem. News. 80, 16 (2004) • Bingham, E., Cohrssen, B., Powell, C., Eds. Patty's Toxicology. New York : John Wiley. (2001) • Useless Information. http://home.nycap.rr.com/useless/teflon/ (2003) • DuPont Electronic Materials Keep Mars Rovers Going. http://www2.dupont.com/Teflon_Industrial/en_US/news_events/article20050120.html (2005) • National Toxicology Program. http://ntp.niehs.nih.gov/ (2005) • Learn more about Teflon®. http://www.teflon.com/NASApp/Teflon/TeflonPageServlet?pageId=/consumer/na/eng/housewares/keyword/teflon_keyword_birds.html (2005) • NIOSH: The National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/homepage.html (2005) • Recycling. http://www.eng.utah.edu/~nairn/mse/students/MSE3410/Teflon/Recycling.html (2003)