Thursday, July 18, 2013

Teflon

Teflon

In 1938, a dupont scientist was researching refrigerants, when he unknowingly created a bizarre new material. It took an adventurous young chemist named Roy Plunkett to make the bold decision that gave us Teflon.


In the early 1930s GM was looking for a safer refrigerant to use for their Frigidaire line of refrigerators. They needed to find a replacement for ammonia, sulfur dioxide, and propane, the refrigerants used at the time, because they were too dangerous for use in homes.GM -- Researching Refrigerants

Ultimately they discovered two chlorofluorocarbons, or CFCs; GM called their new refrigerants Freon 112 and Freon 113.
GM had made the discovery, but their expertise was in making machinery - cars and refrigerators - not chemicals. To refine and mass-produce Freon, GM looked to DuPont.

GM & DuPont

The two companies formed a joint venture called Kinetic Chemicals. While testing the new refridgerants, they actually developed a more efficient version, Freon 114.
Unfortunately, Kinetic's entire output of Freon 114 was earmarked for GM, so DuPont started looking for its own refrigerant. One of the scientists assigned to this task was a 27-year-old Ohio State chemistry Ph.D. named Roy J. Plunkett.

Roy J. Plunkett, Ph.D

Plunkett hypothesized that a new refrigerant could be made by combining tetrafluoroethylene, or TFE, with hydrochloric acid. During experiments, Plunkett and his assistant Jack Rebok used tanks filled with compressed TFE.
They stored these tanks in dry ice to keep the gas inside from expanding too much, and exploding.
On the morning of April 6, 1938, Plunkett and Rebok set up for an experiment. Rebok connected a TFE tank and opened the valve, but to both of their surprise, nothing came out.
Plunkett and Rebok weighed the tank to see if the gas had leaked out. Another surprise - the tanks were still full. They unsuccessfully tried to unclog the valve wire. Out of frustration, Plunkett took the valve off of the tank and shook it. White flakes fell out.

Discovery!

Plunkett immediately sawed the tank in half. Inside they found a white, waxy coating. Plunkett wrote in his lab book that, "a white solid material was obtained, which was supposed to be a polymerized product."
It was commonly believed that TFE could not be polymerized, but that didn't deter Plunkett. He experimented with the new compound, discovering in two days that it is thermoplastic, melts at a temperature approaching red heat, and boils away.
It is insoluble in just about everything: cold water, hot water, acetone, ethers, acids, and alcohols. It doesn't char or melt under a soldering iron, it doesn't rot, swell, mildew, mold, or degrade in sunlight.
Plunkett needed to make sure this new substance was viable, so he conducted an experiment to recreate it. When the experiment succeeded, Plunkett knew he had something groundbreaking on his hands.
Plunkett applied for a patent on July 1, 1939 in the name of Kinetic Chemicals. In 1941, patent 2230654 was granted.

First Uses

Teflon's first use was in gasket seals for the Manhattan project. Teflon also found a home as the nosecone material on proximity bombs - it was resistant to electricity and transparent to radar, making it interference-free to the proximity fuse.
After the war, DuPont released Teflon for commercial and industrial uses. By 1953 Teflon had found its way into industrial kitchens, but was still being tested for release to the general public.
While DuPont tested, a french engineer named Marc Gregoire obtained a small amount of Teflon, intending to coat his fishing gear with it. Recognizing a more useful way to employ non-stick, Gregoire's wife asked him to coat her frying pans. The result was so successful that Gregoire patented non-stick cookware in 1954 and set up a factory in 1956.
By 1960 Teflon had appeared on cookware in American departments stores. Today "non-stick" cookware can be found in nearly every kitchen in the world, commerical or home.