From plastic bottles, to rubber tires, to the DNA in your
cells, our world is full of compounds known as polymers. Polymers are a unique
class of materials which are made up long chains of repeating structural units
called monomers and are a subset of a larger family of molecules known as macromolecules.
Last week when discussing sugars, I mentioned polysaccharides, which are in
fact polymers chains of monomer sugar units!
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| Courtesy of wikipedia.com |
If you’ve ever seen a cooking infomercial or been in the cooking section of a store, you’ve probably heard something called Teflon®. While Teflon® is the registered named used by DuPont™, the chemical itself is specifically called polytetrafluoroethylene. Breaking the name into its individual parts can help make sense of its structure: poly (many), tetra (four), fluoro (fluorine), ethylene (two carbons), and commonly its name is abbreviated PTFE.
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| A glitter/water mix rolling across a PTFE coated surface Courtesy of article.wn.com |
Consisting of entirely carbon and fluorine (see above image), PTFE is a high
molecular weight compound which is white solid at room temperature. As a material,
PTFE is hydrophobic, meaning it is not wetted by water or water containing
substances. From a qualitative point of view, this means that water simply rolls
off of PTFE coatings without sticking (see right insert); giving the material its unique ability
to keep pots and pans clean! For this reason, Teflon® is also commonly used as a lubricant
in industrial equipment.
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| Courtesy of wikipedia.com |
Like many scientific advances, PTFE was actually discovered
by accident. While attempting to make new refrigerants, a scientist named Roy
Plunkett noticed that the tetrafluoroethylene gas tank he was using would stop
flowing before the gauge on the bottle read empty. After filling the bottle
several times and noting this, he finally decided to saw open the bottle and
see what was happening. Within it he discovered a waxy white material which was
extremely slippery which had been created due to the high pressures in the
bottle and the bottles iron metal which was acting as a catalyst for the
chemical reaction. The technology was not applied to pan coatings for another
20 years when “The Happy Pan” hit the US market in 1961.
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| Greedy Fluorine |
While it may seem scary that this compound which coats our
pots and pans contains fluorine, a compound unfamiliar to many consumers, in
reality, fluorine is what gives this material many of its unique and beneficial
properties. The carbon-fluorine bonds are
polar meaning that the electrons which form the bond are not evenly distributed
between carbon and fluorine. As an
element fluorine is extremely greedy with electrons, and as such it pulls the
bonding electrons away from the carbon, bringing the two atoms closer together and
forming the strong bond. In fact, the
carbon-fluorine bond is the strongest bond known in organic chemistry!
Due to this strength, carbon-fluorine compounds are
generally unreactive, making it a great coating for pots and pans. If pans are
heated above 500°F, the coating can begin to break down and pose some
health effects. For reference, meat is typically fried around 400°F
and most household oils will begin to smoke long before reaching the 500°F
benchmark, so there’s no need to be alarmed!
Sources:
- http://en.wikipedia.org/wiki/Polymer
- http://en.wikipedia.org/wiki/Polytetrafluoroethylene
- http://www2.dupont.com/Teflon/en_US/index.html
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