Nathan Corbett, of Kings High School, asks :-

There are frying pans made with a non-stick Teflon coating. If nothing sticks to the Teflon coating then how does it stick to the pan?

Alan Happer, a chemist at the University of Canterbury, responded.

The non-stick frying pan is a triumph for modern technology. Louis Hartmann, in the 1950's, found a way to bond Teflon (polytetrafluoroethylene or PTFE) to aluminium. He treated the metal surface with hydrochloric acid, applied Teflon as an emulsion, and then baked the pan at 400 Celsius for a few minutes. The acid etched tiny pits into the surface of the metal and the PTFE flowed into them. When the pan is heated the PTFE forms one continuous film of Teflon that is held tight to the surface by the polymer trapped in the millions of cavities on the surface.

It may be noted in passing that the problem of fabricating Teflon is a major one as it is very viscous when it melts, and if it is heated to make it less viscous it decomposes. It is usually handled as some sort of powder or dispersion, that is sintered at the final stage.

The fabric known as Gore-Tex owes its special properties to a Teflon membrane with tiny holes in it made by stretching a Teflon film. This is inserted between two layers of fabric. These holes are small enough to keep water droplets out, but large enough for molecules of water vapour from persperation to pass through and escape.

A good source for such information is the book 'Molecules at an Exhibition: Portraits of intriguing materials in everyday life' by John Emsley (Oxford University Press, 1998).