CAROTHERS, WALLACE HUME

(b. Burlington, Iowa, 27 April 1896;

d. Philadelphia, Pennsylvania, 29 April 1937), chemistry, organic chemistry, polymer chemistry. For the original article on Carothers see DSB, vol. 3.

Since the mid-1980s, a number of in-depth studies on Carothers, based on a large quantity of manuscripts, letters, and documents, have revealed some important aspects of his scientific career and work, such as his early encounter with chemistry, the origins of his polymer research, the process of his invention of nylon, and the industrial context in which Carothers worked on polymers.

Early Years . When Carothers was a high school student in Des Moines, Iowa, his early interest in chemistry began with his reading of Robert K. Duncan’s popular books, The New Knowledge: A Popular Account of the New Physics and the New Chemistry in Their Relation to the New Theory of Matter (1905), an exposition of recent theories of matter, and The Chemistry of Commerce: A Simple Interpretation of Some New Chemistry in Its Relation to Modern Industry (1907), which stressed the importance of pure science for industry. While at Tarkio College in Missouri, Carothers decided on chemistry as his life’s work, largely at the encouragement of his chemistry teacher, Arthur M. Pardee. The synthetic-chemical approach and industrial orientation of Roger Adams at the University of Illinois also exerted a profound influence on Carothers’s style in chemistry and his career.

Before moving to the DuPont Company, Carothers had neither published nor performed any experiment in the field of polymers. In the spring of 1927, when DuPont approached Carothers to offer him a position in its newly established fundamental research program in Wilmington, Delaware, the company promised to leave the selection of research subject entirely to him. Carothers chose polymers and polymerization as his new research subject because of the need for theoretical exploration as well as the vast commercial implications of polymers. Had it not been for the DuPont job offer, it is unlikely that the young Harvard instructor would have set out on a journey into the frontier of polymer research.

Carothers had been reading recent German articles on the structure of polymers by Hermann Staudinger and his opponents. Since the early 1920s, Staudinger had proposed the theory that polymers, such as rubber, cellulose, resins, and proteins, were made up of very large molecules, what he called “macromolecules.” His theory was severely criticized by many chemists, who claimed that polymers were the aggregates of relatively small molecules. The unsettled German debate over the existence of macromolecules appealed to Carothers’s theoretical interest.

Research on Macromolecules . By the time he joined DuPont in early 1928, Carothers had already developed his ideas into a coherent program for the synthesis of macromolecules by the use of established condensation reactions such as esterification. He did not intend to produce a synthetic fiber when he started working at DuPont; what he intended was simply to make molecules as large as he could in order to examine the properties of the products. If the products exhibited properties (such as elasticity and fibrousness) similar to natural polymers, then Staudinger’s claim that polymers were composed of macromolecules would be supported.

Overcoming technical difficulties, his group was able to synthesize what he called “superpolymers,” polymers with molecular weights of ten thousand or more. This success was soon followed by the discovery of the “cold-drawing” phenomenon peculiar to these materials. In April 1930, his co-worker Julian Hill observed that a superpolyester could be mechanically drawn out from a melt or dry-spun from a solution into fibers or threads. This led Carothers to foresee the possibility of making artificial fibers from linear-condensation superpolymers.

Realizing its practical implication, DuPont management delayed publication of Carothers’s paper on super-polymers and recommended that the result should be thoroughly protected by a well-planned patent program. This restriction appeared to abridge the academic freedom assured him at the inception of the fundamental research program. From this time on, Carothers’s basic research group was obliged to shift its aim to a more practical goal, that is, to the search for polymers that could be drawn into fibers for commercial use.

During the period from 1930 to 1933, Carothers and his group systematically investigated various types of linear condensation superpolymers, including polyesters, polyanhydrides, polyacetals, polyamides, and polyester-polyamide mixtures, which were synthesized by his coworkers from hundreds of possible combinations of starting materials. After careful consideration, the company selected a superpolyamide for manufacture, first synthesized by a co-worker, Gerard Jean Berchet, in February 1935. The fiber was named “nylon” in 1938, after examining some four hundred names submitted by DuPont employees (the naming committee decided on “nylon” by arbitrarily modifying the finalist “no-run”). Nylon would become the most successful commercial product in DuPont’s research and development history. A year and half before DuPont announced nylon, however, Carothers committed suicide by taking cyanide in a hotel in Philadelphia. He neither lived to hear the name nylon nor to see its enormous commercial production and subsequent impact on culture.

The nylon venture, which would become a prototype for the science-based polymer industry, also turned out to be a large-scale test of the validity of the macromolecular theory. As an industrial researcher, Carothers did not train students in polymer chemistry. Yet he introduced a number of able research chemists at DuPont to the world of polymers. From June 1928 to his death in April 1937, he had a total of twenty-five co-workers, most of them only slightly younger than the group leader, including twenty chemists with PhD degrees. The “Wilmington School” bequeathed a research tradition on polymers not only within the company, but also to American academe. Under Carothers’s influence, a new generation of polymer chemists emerged in American universities. Paul J. Flory, Elmer O. Kraemer, and Carl S. Marvel were among the influential scholars who inherited Carothers’s legacy.

American polymer chemistry, which first emerged from a basic research program in industry, gradually spread as an academic discipline by the late 1940s. DuPont’s venture into fundamental research was rewarded by discoveries that not only had great industrial value, but also sparked original theoretical innovations. Even beyond the perspective of a single company, industrial research turned out to play a seminal role in the birth of a new science in America.

SUPPLEMENTARY BIBLIOGRAPHY

Papers of Wallace Hume Carothers and DuPont Company documents are stored at the Hagley Museum and Library, Wilmington, Delaware. Correspondence between Carothers and Roger Adams is in the Roger Adams Papers at the University of Illinois Archives, Urbana-Champaign, Illinois.

OTHER SOURCES

Furukawa, Yasu. Inventing Polymer Science: Staudinger, Carothers, and the Emergence of Macromolecular Chemistry. Philadelphia: University of Pennsylvania Press and Chemical Heritage Foundation, 1998.

Hermes, Matthew E. Enough for One Lifetime: Wallace Carothers, Inventor of Nylon. Washington, DC: American Chemical Society and Chemical Heritage Foundation, 1996.

Hounshell, David A., and John K. Smith. Science and Corporate Strategy: Du Pont R&D, 1902–1980. New York: Cambridge University Press, 1988.

Morawetz, Herbert. Polymers: The Origins and Growth of a Science. 1985. New York: Dover, 1995.

Yasu Furukawa

Carothers, Wallace Hume

(b. Burlington, Iowa, 27 April 1896; d Philadelphia, Pennsylvania, 29 April 1937),

chemistry.

Wallace Carothers was the eldest of the four children of Ira Hume and Mary Evelina McMullin Carothers. His early education, in Des Moines, Iowa, included a final year at Capital City Commercial College, where his father taught and later served as vice-president. In 1915 he entered Tarkio College in Tarkio, Missouri, supporting himself as a student by teaching accounting, English, and his major interest, chemistry. He received his bachelor’s degree at Tarkio in 1920 and his master’s degree at the University of Illinois in Urbana in 1921. After teaching for a year at the University of South Dakota, he returned to Urbana and in 1924 earned his doctorate, with a major in organic chemistry and a dissertation on hydrogenations with modified platinum-oxide-platinum-black catalysts, under the direction of Roger Adams. He remained there for two years as instructor in organic chemistry and in 1926 accepted a like position at Harvard University. In the period 1923–1927 he published his first four independent papers, of which the most notable—on the electronic nature of the double bond—confirmed his early promise of brilliance and originality.

A turning point in Carothers’ career came in 1928, when he joined E. I. du Pont de Nemours and Company to lead the organic group in a program of fundamental research at its central laboratories in Wilmington, Delaware. At the time this was a radical departure in industrial research, and the opportunity thus offered to undertake basic research with a group of postdoctoral associates and maximum physical support overcame Carothers’ reluctance to leave the academic world. The ensuing nine years until his premature death were extraordinarily productive, resulting not only in major contributions to theoretical organic chemistry but also in the founding of two industries, the production of synthetic rubber and of wholly synthetic fibers for textile and industrial purposes. In 1936 Carothers was elected to the National Academy of Sciences, the first organic chemist associated with industry to be so recognized.

Although he was modest to the point of shyness, Carothers’ personal warmth, generosity of spirit, and sense of humor inspired deep affection in his friends. He was married 21 February 1936 to Helen Everett Sweetman of Wilmington, Delaware, and a daughter, Jane, was born 27 November 1937. His death, by his own hand, followed a long history of intensifying mental depressions, despite the best medical advice and care.

The first area that Carothers chose for intensive investigation at Du Pont was the synthesis of polymers of high molecular weight by means of simple, well-understood reactions, such as esterification and amide formation. Using as reactants compounds that can be generalized as xAx, yBy, and xCy, where x represents hydroxyl (—OH) or amino (—NH₂) groupsand y the carboxyl (—COOH) group, his team prepared and studied in detail a great number and variety of linear polymers of general formula

xAzBz(AzBz)_nAzBy or xC(cz)_nCy.

A, B, and C represent chains of carbon atoms, and z represents an ester (—OCO—) or amide (—NHCO—)group formed by reaction of an hydroxyl or amino group with carboxyl. When the factor n attained some minimum high value, the polymers proved capable of being formed into fibers that, after being stretched to orient the chain molecules into parallel configuration, were strong, flexible, and tough. The outcome of these studies was a great advance in the understanding of the chemistry and properties of both natural and synthetic polymers and the opening of new avenues of experimentation in polymerization. A massive development program on one of these new fiber-forming polymers, based on hexamethylene diamine and adipic acid, led to the first nylon, the manufacture of which the Du Pont Company started in 1939 at Sea-ford, Delaware.

Carothers’ second major area of investigation was the chemistry of vinylacetylene and divinylacetylene, low polymers of acetylene that were available from the discoveries of Nieuwland and work in other Du Pont laboratories. These studies led to a wide range of derivatives, the most important of which was chloroprene (2-chlorobutadiene), made by adding hydrogen chloride to vinylacetylene. This compound, the chloro analogue of isoprene, was shown to convert readily to a polymer having elastic properties like those of rubber. Du Pont started manufacture of this product, called neoprene, in 1931. Alone and with collaborators, Carothers published sixty-two scientific papers and was granted sixty-nine U.S. patents, many of which were equivalent in content to scientific papers.

BIBLIOGRAPHY

Carothers’ papers were brought together in Collected Papers of Wallace H. Carothers on Polymerization, H. Mark Whitby and G. S. Whitby, eds. (New York, 1940). Roger Adams, in Biographical Memoirs. National Academy of Sciences, 20 (1939), 293–309, contains a complete list of Carothers’ scientific papers and most of his U.S. patents. See also Dictionary of American Biography, supp. 2 (New York, 1958), 96–97.

Julian W. Hill

Wallace Hume Carothers

The American chemist Wallace Hume Carothers (1896-1937) was an experimentalist in the organic and industrial branches. His researches into polymerization led to the invention of nylon, the first truly synthetic fiber.

Artificial fibers, in the sense of being man-made, had been known since the closing decades of the 19th century; the first patents for processes resulting in fibers of the type later known as rayon were taken out as early as 1885. Once it had been discovered by x-ray analysis that natural fibers were composed of molecules that were themselves long and narrow, the possibility of building up such long molecules from small units, so producing new fibers, had been envisaged. Wallace Carothers, who more than anyone enabled this possibility to be realized, died the year before the creation of nylon was announced by E. I. du Pont de Nemours and Company, whose research team he had led with such distinction.

Carothers was born on April 27, 1896, in Burlington, lowa, to Ira Hume Carothers, teacher of commercial subjects, and Mary McMullin Carothers. In 1915 he entered Tarkio College, Mo., specializing in chemistry. After the outbreak of World War I he was asked to teach chemistry, no experienced instructor being available. After he obtained his bachelor of science degree in 1920, he enrolled in the chemistry department of the University of Illinois.

In 1921-1922 Carothers taught analytical and physical chemistry at the University of South Dakota. About this time he began to pursue independent research problems. He became interested in the recent valency theory of lrving Langmuir and investigated its relevance to organic chemistry. After receiving his doctorate in 1924 for research on the reduction of aldehydes with a platinum catalyst, he stayed on at Illinois for 2 years, teaching organic chemistry, and in 1926 moved to Harvard.

In 1928 the Du Pont Company, which had planned a new program of fundamental research, selected Carothers to lead the team in organic chemistry at its experimental station at Wilmington, Del. He was allocated a small group of trained research chemists to work on problems of his own choice. In the 9 years that followed, he made several major contributions to fundamental theory, as well as laying the foundations for the development of new materials.

Synthetic Rubbers

After the discovery in the 19th century that rubber on heating yields the liquid hydrocarbon isoprene, it gradually became apparent that its molecules were long chains of isoprene units; attempts to polymerize isoprene, however, merely produced sticky, rubbery substances of no commercial value. The exhaustive studies of acetylene compounds made by Carothers's team led to the crucial step about 1931, when they found a workable process for converting the hitherto little-known and unstable substance monovinyl acetylene to chloroprene (closely related to isoprene). This, on polymerization, yielded what is now known as neoprene, superior in many respects to the natural product.

Discovery of Nylon

Carothers's greatest accomplishment was his work in the related field of polycondensation, that is, the linkage of pairs of compounds, instead of identical units, with the elimination of some simple substance such as water. He prepared a number of polyester fibers, but these seemed to be unpromising, chiefly owing to their low melting points (later, however, this road led to Dacron and Terylene). The polyamide Carothers produced from adipic acid and hexamethylenediamine was eventually selected by Du Pont's textile experts for development and became known as Nylon-66 ("six-six"), since each of the constituent molecules contains six carbon atoms.

Carothers was elected to the National Academy of Sciences in 1936. He suffered from periodic fits of depression, which steadily grew worse; during one of these he ended his own life.

Further Reading

Roger Adams wrote a short biography of Carothers which was published in the National Academy of Sciences, Biographical Memoirs, vol. 20 (1939); this biography, slightly shortened and lacking the bibliography of Carothers's papers, is reprinted in Eduard Farber, ed., Great Chemists (1961). The development of synthetic rubbers and fibers, including the work of Carothers, is discussed in John Jewkes, David Sawers, and Richard Stillerman, The Sources of Invention (1958), and in James G. Raitt, Modern Chemistry: Applied and Social Aspects (1966); both books give useful references for further reading. For a history of chemistry which includes the work of Carothers see Aaron J. Ihde, The Development of Modern Chemistry (1964).

Additional Sources

Hermes, Matthew E., Enough for one lifetime: Wallace Carothers, inventor of nylon, Washington, D.C.: American Chemical Society, 1996. □

Wallace Hume Carothers

1896-1937

American Chemist

Wallace Carothers quite literally transformed the texture of human life. His assignment as director of a research team for the DuPont Company marked the culmination of a promising career, and the promise bore fruit: Carothers's experiments with polymer plastics yielded nylon, one of the most significant inventions of the twentieth century, and the first synthetic fiber. He would probably have won a Nobel Prize, as some have speculated, yet just before he turned 40, Carothers—who in addition to his career successes was a newlywed with a first child on the way—took his own life.

Carothers was born on April 27, 1896, in Burlington, Iowa, the oldest of Ira and Mary McMullin Carothers's four children. His sister, Isobel, was destined to go on to celebrity as a member of the radio musical trio "Clara, Lu, and Em." Carothers's father was a teacher at Capital City Commercial College in Des Moines, and the son enrolled there to study accountancy in 1914. A highly advanced student, he completed the accountancy program in just one year, and went on to study chemistry at Tarkio College in Missouri.

During World War I, wartime duties forced Arthur Pardee, head of the chemistry department, to leave Tarkio. Unable to replace him, the college appointed Carothers, who was ineligible for military service due to health reasons, to take his place—this despite the fact that he was only an undergraduate. Carothers earned his B.S. in chemistry in 1920, and went on to the University of Illinois, where he completed his master's degree a year later.

Pardee convinced Carothers to join him at the University of South Dakota, where he taught for a year, but by 1922 he was back at the University of Illinois to complete his Ph.D. work. He earned his doctorate in 1924, then began teaching at the university. In 1926, however, Harvard selected Carothers above numerous candidates, and he went east to teach. At Harvard, he began experimenting with high molecular weight polymers, an activity that attracted the attention of the DuPont Company. In 1928, DuPont invited him to direct a new research program at their headquarters in Wilmington, Delaware, where Carothers would head a team of scientists. It was an offer even more attractive than Harvard, and 32-year-old Carothers accepted.

At first Carothers focused on molecules in the acetylene family, and by 1931 his experiments with combinations of vinylacetylene and chlorine had yielded a synthetic rubber that the company marketed as neoprene. This alone would have been a great claim to fame, but within a few years Carothers produced something even greater, a synthetic equivalent of silk. He knew that he needed to create a chemical reaction that would produce long molecules oriented in the same direction. A series of experiments led to an understanding of how polymers were created, and this in turn yielded nylon. The latter would debut in 1938, and became a huge sensation at the World's Fair a year later. By then, however, Carothers was dead.

In 1936, he married Helen Sweetman, who worked in the patent division at DuPont. Though highly enthusiastic about his work, Carothers was always shy and withdrawn, so his marriage must have come as a surprise. He was, however, a talented singer, something he shared with his sister Isobel, his closest sibling. Her death in January 1937 sent him into a bout of depression, and on April 29, he committed suicide in Philadelphia. Seven months later, on November 27, Helen gave birth to a daughter, Jane.

JUDSON KNIGHT

Carothers, Wallace Hume (1896–1937) US chemist who discovered the synthetic polyamide fibre now called nylon.