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    Teflon: A Guiness Record Holder

    Kids, did you know that teflon is listed in the Guiness Book of World Records as the slipperiest material in the world? The secret lies in its highly stable covalent bonds. Let¹s learn more about teflon's chemistry and do a little test of its amazing properties.

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    Teflon is a polymer with long chains of strong carbon-carbon bonds. The long chains are strung together from short tetrafluoroethylene (C2F4) molecules. The tradename teflon is actually a short version of the chemical name polytetrafluoroethylene (PFTE). Each carbon in the chain also has two fluorines attached to it, and C-F bonds are exceptionally strong. The C-F bonds are so strong that virtually nothing can break them apart. Not other chemicals and not high temperatures. It is therefore perfect for nonstick coatings on cookware.

    Try this test using teflon tape. PFTE tape is available in most hardware stores because plumbers use it to make water-tight seals between threaded pipes. Cut a 10-15 cm length of this tape and stretch it a bit lengthwise. Now stretch it a little bit widthwise and note the difference. Now stretch it again lengthwise and note what happens. Cut a new length and with a permanent marker carefully print your name on the tape. You'll have to write very lightly and hold the ends tightly (perhaps a friend can help) because the tape will want to bunch up. It's tricky but you can do it if you're careful. Slowly stretch the tape widthwise in a few places to distort your name beyond recognition. Now pull the two ends apart and voila! your name will appear again. Redistort and try again. Think about the properties of teflon tape that let you do this. A common question is: if nothing sticks to teflon, how can teflon stick to a pan? DuPont uses a procedure (called stratification) in which a mixture of materials is baked onto a metal pan at a high temperature (about 420°C). During this treatment, binder molecules in the mixture attach to the pan, and the fluoropolymer molecules rise to the top of the coating. The result is a non-stick surface that stays in place. Check out www.dupont.com/afs for details on the development of teflon and other applications. Next month: Kevlar!

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    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    December 1999

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    Reference: "ChemMatters" 10/99, p. 16, by R. Becker; American Chemical Society, Washington, DC.