Categories: Accidental discoveries , Chemistry in History , Guest posts |  Comments
Guest post by Rowena Fletcher-Wood
I first heard the story of the discovery of nylon during a chemistry class in school – it was told as a serendipitous discovery. A young lab assistant, clearing up at the end of a long day, clumsily poured two mixtures in together and noticed a precipitate. Dipping in a stirring rod, he pulled out a thin string, which he stretched out into a tough, translucent fibre. He realised the potential of his discovery, reported it to his superiors and left them to the tiresome job of working out what he had done to make it.
It’s funny how we use accident to shape our understanding of discovery and achievement, as though we want to excuse hard work and apologise for years of learning. It’s somehow disappointing, unromantic: the story of research whisks away that tantalising fantasy of stumbling upon treasure, reserving discovery for the experts.
The real story of nylon, interesting though it may be, is a bit of stretch from serendipity.
There was a young lab assistant, and his name was Julian Hill. He was working in the DuPont research laboratory, led by the rigorous organic chemist Wallace Hume Carothers, who had taken on the challenging ‘synthetic fibre race’. At the time, synthetic polymers were a mysterious conception; what they were made of and how they related to simpler compounds was unknown. The DuPont team had studied complex natural products such as cellulose and silk and from their understanding had developed polyamides through the condensation of dicarboxylic acids with diamines – fantastically interesting but, at the time, not particularly useful.
Julian Hill had been working with polyester when, dipping in a stirring rod, he pulled out a thin string, which he stretched out into a tough, translucent fibre – just like in the story I was told. But this was not considered extraordinary. Often, discovery is not about observing properties, but recognising them. One day, when Carothers was absent from the lab, the chemists decided to go rogue with the polyester and have a competition to see how long they could stretch it. They raced down the hall, delicately extending the fibre. They had extended it to four times the original length when it stopped. It would not stretch any more.
Suddenly, Hill understood: as they stretched the fibre, chains of molecules snapped into position, orienting themselves into a chain of a discrete thickness. This would be the basis for the first fully synthetic fibres.
But nylon was far from invented. The melting points of the polyesters they had were far too low for any practical applications, and so they returned to polyamides and began stretching those instead. It took 9 months, a patent for the ’cold-drawing’ process of making fibres by removing them from the water of condensation, and 80 new polyamides before the most promising, nylon-6,6, was discovered in May 1934.
Nylon, a dyeable, durable, shiny thermoplastic first entered the market in 1938 as the bristles of a toothbrush, before being appropriated for women’s hosiery in 1940. DuPont declined to trademark the name ‘nylon’, instead allowing it to enter the lexicon as an alternative name for ‘stockings’. The new ‘nylons’ were a huge success. Nowadays, this fantastic fabric, which leaves a lower carbon footprint than wool, is used for meat wrappings, instrument strings and carpets, amongst many other things. Its only downside is its toxicity upon heating: it melts rather than burns, and breaks down to produce hydrogen cyanide.
This is ironic, actually, because Carothers never got to see his creation take hold. In 1937, just as his achievements were being celebrated and developed, he committed suicide with cyanide. He had suffered with depression and was grieving for the loss of his sister, but his suicide came as a shock. The suicide has been described as an ‘embarrassment’ for DuPont, and records relating to Carothers were lost or destroyed. This may help to explain why the discovery of nylon has since been wrapped in myth and mystery.