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PLUNKETT REMINISCES

Roy Plunkett looks back on the invention of fluoropolymers from the 25th Anniversary of "Teflon"

( From the Journal of TeflonÒ, March-April 1963)

"A lot's been said and written about what happened when I discovered polytetrafluoroethylene. It's more than just sawing open cylinders, though; you have to look at what we were trying to get done by our experiments at the time."

"Tetrafluoroethylene was the intermediate we were using in synthesizing a partially chlorinated fluorocarbon, later it was meant to be used for a refrigerant. DuPont was manufacturing fluorocarbons for refrigeration uses, and this was part of the back-up work we were and are always engaged in.

"I needed about 100 pounds of tetrafluoroethylene. For several weeks we had been making our own TFE and storing it in pressure cylinders. We kept these cylinders stored with dry ice, as a routine procedure, until we were ready to use them. Then as we needed TFE we'd bring one of the cylinders up to the lab and tie it into the apparatus.

"That morning, April 6, 1938, my assistant, Jack Rebok, had gotten one of the TFE cylinders we'd been using the past few days. He had the apparatus ready to go. When he turned the valve to let the TFE flow out under pressure from the cylinder, nothing happened!

"Jack called me over and asked me whether we hadn't used up all the TFE in that cylinder. I told him I didn't think we had, since it originally contained a kilogram of TFE. So we both tinkered with the valve a bit, and then, thinking it might be stuck or closed in some way, we disconnected the cylinder from the line, and got a wire and pushed it down through the valve opening. Still no TFE came out, although the weight of the cylinder showed that there was still material inside.

"Well, this had us somewhat in a quandary. I couldn't think of anything else to do under the circumstances, so Jack and I unscrewed the valve from the cylinder. By this time it was pretty clear that there wasn't any gas left.

"I carefully tipped the cylinder upside down, and out came this whitish powder down onto the lab bench. We scraped around some with the wire inside the cylinder or maybe I tapped it, I don't remember just which, to get some more of the powder. What I got that way certainly didn't add up to a kilo, so I knew there must be more inside.

"Finally, more out of curiosity I suppose, than anything else, we decided to cut open the cylinder. When we did, we found some more of the powder packed down around the bottom and lower sides of the cylinder.

"My first reaction to discovering that the TFE had apparently polymerized inside the cylinder was: now we'll have to start all over again! Jack felt about the same. Of course neither of us quite realized what we had stumbled onto. It didn't occur to me right away what possibilities the material might have. That had to wait until I could get some lab tests run on it. But there was no doubt in my mind that the TFE had in some fashion polymerized."

"Within a few weeks, after lab tests showed me how the new polymer behaved, the real research got under way and I started trying to duplicate what took place. At one time I even used a mixture of TFE, silver nitrate, and methanol. This time I got a jelly-like substance, which was probably a polymer with much shorter chains than the original one I discovered. We used that experiment as one of the examples in my patent."

"Before it happened, I didn't know that given the right chance, TFE would polymerize. But looking back on the discovery, what's more significant to me is that storing a cylinder with a kilogram of TFE in it could have been the end of both Jack and myself! Spontaneous polymerization of TFE can lead to explosive reactions."

What was the greatest satisfaction Roy Plunkett derived from his discovery? Certainly not the John Scott Medal, bestowed on him in 1955, or any of the other citations awarded him since the historic event. In his own words:

"I feel that something I worked on has been of great personal benefit to people. Not just indirectly, but directly, to some real person whom I know. Two years ago at a social affair, I was introduced by a doctor friend of mine to a man who'd been suffering from a heart defect. 'See that fellow dancing over there?' asked my friend, 'He's alive today because he's got apiece of your plastic in his heart.' That sort of makes the occasional discouragements of research a lot easier - I believe I've been more than just helpful; I've made a real contribution."