Teflon

Teflon (registered trademark of Dupont for their crazy slippery polymer)...
was accidentally invented by DuPont chemist Roy Plunkett, in (or near) 1938. Very chemically stable, high melting point, and weirdly slippery in solid form, it is used as a non-stick coating on cooking and messy industrial process surfaces. The difficulty of sticking anything to Teflon makes it a good candidate for an easy-cleaning surface in high-spill areas, although it is pretty expensive to throw around in home applications.

Teflon was discovered by accident by Dr. Roy Plunkett at Du Pont on April 6^th, 1938. Plunkett had been attempting to find a better coolant gas. He left a batch in a container overnight, and on returning the next day, the gas had become a waxy solid.

The solid, polytetrafluoroethylene (PTFE) is a chemically inert polymer, is impervious to many corrosives and has a very low coefficient of friction. Teflon is opaque and nearly white in colour. It is 90% crystalline. The name was abbreviated to Teflon for simplicity and is a registered trademark of Du Pont.

Teflon fumes are poisonous. If you heat an empty Teflon coated pan to 400°C, the Teflon particles become airborne and can cause polymer fume fever. However, it is totally safe in normal cooking conditions. Solid Teflon is harmless to humans.

Commercial use didn't take off until 1948 and its applications were mostly industrial. This includes electrical insulation, frictionless bearings and gaskets. It wasn't until 1950 that Parisian Marc Gregoire devised a way of applying Teflon to fishing tackle to prevent tangling. His wife thought of the idea of non-stick pans. Gregoire created and sold over a million pans, under the trade name Tefal.

The idea didn't reach America until a reporter called Thomas Hardie visited a friend who had recently returned from Paris, with the non-stick cook-ware. Hardie was stunned and struck up a deal with Gregoire to market the pans in America. He imported 3000 but couldn't get support from any major department stores. Eventually, Macy's Herald Square purchased 200, which sold out in 2 days.

Demand rocketed but before Hardie could construct a manufacturing plant, every pan manufacturer had caught on to the idea.

One question: If Teflon doesn't stick to anything, how does it stick to the pan?

While Teflon cannot chemically bond with anything, it can mechanically bond. The surface of the pan is sandblasted and a primer is applied. The Teflon is then embedded into the primer.

Teflon was discovered with so little research in part because its structure is extremely simple and able to assemble itself without a long series of reactions. Molecular simplicity is also accountable for the material's inert nature and resistance to heat. A carbon atom is covalently bonded to another carbon atom, which is bonded to another, and so forth so that there's a long string of carbons. Since carbon forms four covalent bonds, each carbon in the chain has the two bonds free, which each attach to a fluorine atom. This long string of PTFE arranges its bond angles so each carbon atom is cushioned by its own two fluorine atoms one one side, and the four fluorines belonging to its neighbor on the other, leaving it largely protected from reaction.

Here's a janky ASCII rendition of a few links of PTFE chain. Of course it's actually three dimensional, not flat, so render the angles in your mind to make it look more like a snake and less like a flatworm.

  F   F   F   F   F   F   F   F   F   F   F  
   \ /     \ /     \ /     \ /     \ /     \ 
   -C-     -C-     -C-     -C-     -C-     -C
  /   \   /   \   /   \   /   \   /   \   /  
C-     -C-     -C-     -C-     -C-     -C-   
 \     / \     / \     / \     / \     / \   
  F   F   F   F   F   F   F   F   F   F   F  

Having a uniform cross-section means the molecule is non-polar, adding to its inertia. Also, since other fluorine atoms are the last thing the bonded fluorine atoms want to interact with, PTFE has a very stable crystalline nature. That is, the chains tend to stack together like logs, and due to stability of the carbon center, not twist and braid around one another. The lack of kinks in this crystalline solid makes it even more difficult for other chemicals to react with PTFE, and adds to its famed slipperiness (which, as a point of interest, can be expressed as a coefficient of friction usually between .05 and .20).

The explanation of attaching teflon to other materials given above is somewhat lacking, so I'll try to elucidate on it a bit. One way of making teflon sticky is to bombard one side of the solid with a plasma, the ions of which will tend to break off fluorine atoms on that side. After that, a more "sticky" atom, like oxygen, can be bound onto the exposed carbon chain. This will allow the affected side to adhere to a primer or other substance, as jean-yves mentions above. Sometimes two exposed carbons will bind to each other, forming an unsaturated hydrocarbon. While that may distort the PTFE chain somewhat, the hydrocarbons are nicely sticky and will adhere to other substances.