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What makes Teflon non-sticky?

Ever tried to make an omelette in an ordinary frying pan? Did it stick to the pan and give you a hard time getting it off, right? That's why we use Teflon-coated non-stick pans. Let's see what is non-stick about it.

Why things stick, and Teflon doesn't

Whether things stick or not depends on friction. Friction is the force of attraction between things. Sticky things like gum and starch have very high friction. Once you put them on a surface, they'll hardly move, and not let anything else move. Rubber has a little less friction and gives a very good grip. That's why it's used to make the soles of shoes as well as the tyres of trucks. Water and oil have very low friction. Teflon has almost no friction at all.

Try this at home. Get two frying pans, one ordinary and one non-stick. Boil some starch, and put a few drops on each pan. Swirl the pan around. Do you notice how the starch drops slip on the non-stick pan? That's because there's practically no friction there. Did the drops tend to spread on the sticky pan?

How do you make Teflon stick to the pan in the first place? The makers of the pan give it a very, very rough surface, full of tiny holes. They then pour molten Teflon over it. The Teflon gets stuck in the tiny holes, and as it sets, forms a smooth, non-stick layer.

How it came to be coated on pans

Teflon is a chemical made by the DuPont company. Its actual name is quite long - polytetrafluoroethylene (PTFE). It is a compound of carbon and fluorine. It is similar to CFCs, the compounds that were earlier used to make refrigerator cooling liquids. But these got banned by the Montreal Protocol to save the ozone layer.

It was discovered quite by accident in 1938. A scientist called Roy Plunkett was trying to make a new type of CFC for use in refrigerators. He was using a chemical called perfluorethylene, which he stored in iron cylinders. Under the high pressure, the material changed into PTFE all by itself. When he tried to pick it up, it was very slippery (It is the second most slippery thing in the whole world*). He gave it the name Teflon.

In 1954, Marc Gregoire, a French engineer applied a coat of Teflon to his fishing wires. If the wires got tangled up, the Teflon made them to slip and untangle automatically. When his wife saw it, she made him coat her frying pan with Teflon. She reasoned that she could make omelettes without them sticking to the pan. She was right!

Soon, every pan-making company was coating their pans with Teflon.

*Actually, the most slippery thing in the world is diamond, but a diamond-coated frying pan would be very expensive, don't you think?

Tags :     Everyday Chemistry     Teflon     non-stick     friction     DuPont     polytetrafluoroethylene     PTFE    

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