Polymers & Serendipity
Case Studies

Marcy Copeland, Yellow Medicine East High School, Granite Falls, MN
Dan Larson, Anoka High School, Anoka, MN
Dan Morton, Roseville Area High School, Roseville, MN

Many important scientific discoveries have occurred because researchers pursued 'chance' or accidental events. Nowhere is this more evident than in the history of polymers and organic chemistry. Teachers interested in teaching about the process of science will want to convey something about the role of 'serendipity'. Yet it can be difficult for students to appreciate through their own lab experiences how mishaps can be transformed into successes or how 'mistakes' can lead productively to new knowledge. One strategy is to use historical case studies that can connect with easy lab demonstrations. The following familiar molecules each have a fascinating story behind them that helps convey a lesson about the nature of science and--when linked to 'hands-on' lab activities--can also enrich a student's understanding of fundamental organic chemistry:

These stories and related lab activities also offer an ideal opportunity for introducing a unit on organic chemistry into a standard chemistry course (including polymers).

We also recommend as supplemental reading:
Serendipity: Accidental Discoveries in Science, by Royston M. Roberts (New York: John Wiley and Sons, 1989).
and the VIDEO:
Lucky Accidents, Great Discoveries and the Prepared Mind. -- 1/2-inch video #0342, NSP Film Series, 6518 Walker St., Ste. 20, St. Louis Park MN 55426.

The seeds of great discoveries are constantly floating around us, but they only take root in the minds well prepared to receive them. --Joseph Henry

The curriculum material here was developed as part of a project sponsored by SciMath-MN and The Bakken Library and Museum. Click to see directory of other curriculum modules using history and philosophy of science in this series.

Dyes -- Fortunate Accidents

One of the premier scientists of all time, Louis Pasteur, made an important statement for students and educators: "In the field of observations, chance favors only the prepared mind." Many well trained scientists have made discoveries while seeking other results or methods that their background learning and experience called to the attention of their ready minds.

Mauve Dye

One such example resulted in British Patent No. 1984 for the synthesis of mauve dye in 1856. An eighteen-year-old chemistry assistant, William Henry Perkin, undertook the project of trying to prepare artificially the anti-malarial drug, quinine, on his Easter vacation. He started with a simple waste product, aniline, from coal tar. He failed at synthesizing quinine but did produce a mysterious black powder. Given his training and curioisty he tried to discover what it was. He soon found that the powder dissolved in alcohol to produce a stunning purple color. Instead of discarding the solution, Perkin wondered if it might dye fabric. He found that not only did it color silk and cotton, but the color did not wash out with soap or fade when exposed to sunlight. Perkin built a factory to produce his mauve dye and it made him a rich man, allowing him to continue research on coal tar products. Using his accidental experimental results, William Henry worked out the synthesis of the red dye alizarin from anthracene, a component of coal tar. The value of these dyes is not limited to the texttile industry. Researchers have found that bacteria can be stained and show up for microscopy when certain dyes are used. Tuberculosis and cholera bacilli were discovered using this technique.


Another important dye was produced by a somewhat careless accident and an accompanying alert observation. Indigo was an important dye prepared from the indigo plant. In India in 1897 about two million acres were under cultivation growing indigo plants. A chemist named Sapper was heating some organic chemicals together when he accidentally broke a thermometer into the mixture. (No student would ever do this!) His prepared mind noticed a difference in the reaction and, upon further testing, he discovered that a product, phthalic anhydride, had been produced, which could readily be converted into indigo. The mercury in the thermometer had produced a catalyst that helped oxidze the coal tar component napthalene into the unexpected but desired phthalic anhydride.

Monastral Blue

A final example occured in 1928 in Scotland. A.G. Dandridge was operating a chemical plant that produced phthalimide fromammonia and molten phthalic anhydride. Siince the temperatures were quite high, the reaction was performed in a large iron sealed container. Dandridge noticed some strange blue crystals on the cover and sides of the container and was curious enough to collect some for examination. he discovered that they resulted from a reaction between the iron container and the contents. Further study found the chemical structure of the pigments and he named them phthalcyanines. By substituting copper for iron, he produced an even better pigment called 'monastral blue'. This familt of pigments, which have resulted in over thirty patents, have become some of the most valuable coloring materials for paitns, lacquers and printing inks.

Click here for extended LAB ACTIVITIES on dyeing and for more information on the history of dyes in Colonial and Native America.


A team of organic chemists from Du Pont led by Wallace Hume Carothers had been trying to unravel the composition of natural polymers, such as cellulose, silk, and rubber. From this knowledge they hoped to develop synthetic materials that mimicked the properties of these natural polymers. This remarkable group of chemists had developed a group of compounds, polyamides, which had no remarkable or useful properties.

These compounds were shelved in order to concentrate their work on a more promising series of compounds, polyesters. Polyesters possessed more desirable properties such as having more soluble products, easier to handle and simpler to work with in the laboratory. Julian Hill, working with polyester, noticed that if you gathered a small amount of this soft polymer on the end of your stirring rod and drew it out of the beaker, it produced a silky, fine fiber. One afternoon when their boss, Wallace Carothers, was not in the lab, the chemists decided to see how long a silky thread they could produce. Hill and his cohorts took a little ball on a stirring rod and ran down the hall and stretched them out into a string. The realization struck them during this horseplay that by stretching the strand of fiber they were orienting the polymer molecules and increasing the strength of the product.

The polyesters had very low melting points, too low for textile uses, so they retrieved the polyamides from the shelf and began to experiment with this need 'cold-drawing process.' They found that the strand of polyamide produced by this cold-drawing technique produced a stron g, excellent fiber. The patent for the composition of nylon was never applied for by Du Pont, rather they chose to patent the production process -- cold-drawing -- developed by unsupervised adults playing around in the lab.

In January-February 1939, this consumer product hit the US market. It is without equal in its impact before or since. Nylon stockings were exhibited at the Golden Gate International Exposition in San Francisco and were sold first to employees of the inventor company Du Pont de Nemours. On May 15, 1940, nylon stockings went on sale throughout the US, and in New York City alone four million pairs were sold in a matter of hours.

Naming this new polymer too many twists and turns. Initially the name norun was proposed for this new product because it was more resistant to laddering than silk. But there were problems and the name was then reversed to read nuron. However, it was pointed out that this was too close to the word neuron which may be construed to be a nerve tonic. Hence, nuron was changed nulon. However this ran into trade mark problems and the name was again changed to nilon. English speakers differed in their pronunciation of this, so, to remove ambiguity the name finally became nylon.

Two years before the basic patent on nylon had been filed, the discoverer of nylon, Wallace Hume Carothers, suffering from one of his increasingly frequent attacks of depression, caused by his conviction that he was a scientific failure, drank juice containing potassium cyanide. He would be pleased to know that half of all the chemists in the US work on the preparation, characterization, or application of polymers.


The most common nylon is nylon-6,6. The sixes refer to the number of carbon atoms in the two monomer units (see below), one of which is a six-carbon diacid and the other a six-carbon diamine. When these two monomers combine they do so by eliminating a water molecule (condensation reaction) producing a chain of alternating monomers. In the cold-drawing process, the long polymer molecules line up with one another so that the oxygen atom can hydrogen bond with a nitrogen atom on an adjacent chain. The individual polymer molecules are bound together just as strands in a rope. When twisted together, they hydrogen bond forming fibers with great strength. This appears to mimic the natural silk which is also extruded from the silk worm in a cold-drawing process.

part of the nylon polymer molecule

nylon polymer molecules cross-linked by hydrogen bonds after cold-drawing

Accidental Discovery of Rayon, Artificial Silk

In the 1870s, Louis Pasteur was involved in an effort to save the French silk industry from an epidemic affecting silkworms. His assistant, a young chemist, Hilaire de Chardonnet, spilled a bottle of collodion while working in the dark room. Like many of us, he left the clean-up of the spill for another time. When he returned to clean-up his mess, he found that the collodion had become a tacky, viscous liquid due to partial evaporation of the solvent. As he wiped it away, he noticed long, thin strands of fiber which resembled silk. His observation of this fiber-like material and the strong desire to find a silk substitute, was enough to encourage Chardonnet to experiment further with the collodion.

Within six years after the accidental spill, a material resembling silk had been produced. His starting material was mulberry leaves, the natural food of silkworms, dissolved in ether and alco hol. He drew the fibers out and coagulated them in warm air. The unveiling of this artificial silk took place at the Paris Exposition of 1891, where the enthusiasm for this product quickly resulted in financial backing to begin commercial production. This new fiber was called 'artificial silk' until 1924 when the name rayon was first used.

This 'artificial silk' was not only used for clothing, but also to produce movie film. There were some significant problems with this fiber, cellulose nitrate, as it was highly flammable. This material's flammability resulted in several disastrous fires in movie theaters when the projector jammed and the film stayed in the path of the intense light for only a few seconds. Because of this, if was replaced with a 'safety film' produced from cellulose acetate.

Newer rayons have been developed. The two most common are xanthate rayon and acetate rayon. The xanthate rayon, regenerated cellulose, it prepared by converting cellulose into a soluble form, cellulose xanthate. This is then extruded through fine holes into a chemical bath that converts the cellulose xanthate back into cellulose. This process gives the regenerated cellulose a smooth, silky finish unlike the fuzzy appearance of cotton, a natural cellulose. Xanthate rayon is found on labels simply as rayon.

The acetate rayon, found on labels as acetate, is prepared in a similar fashion to ChardonnetŐs early rayon. Cellulose is converted to an acetate ester, rather than a nitrate, which is soluble and can be extruded into smooth fibers. This cellulose acetate is not flammable, but is somewhat soluble in organic solvents, such as acetone. The xanthate rayon is impervious to organic solvents.


Organic molecules are among the most important to our lives and society--plastics, fossil fuels and other petroleum products, biological molecules (DNA, proteins, etc.), drugs, dyes, artificial sweeteners (saccharin and aspartame) and new fat 'substitutes' (olestra). Yet many chemistry classes do not include them. We hope the exercises presented here and the guidleines for a unit in organic chemistry will inspire many teachers to include them, to expand their treatment, or to enrich what they already teach with perspectives in the history and philosophy of science.

A good warm-up activity is to explore a list of 'Polymers in Everyday Life'.

Background information on polymers can be obtained
via WWW at:
or by FTP:
or by sending e-mail message to
mail-server@rtfm.mit.edu with the single-line message ("Subject" line blank):