Wallace Carothers
Encyclopedia
Wallace Hume Carothers was an American
chemist, inventor and the leader of organic chemistry
at DuPont
, credited with the invention of nylon
.
Carothers was a group leader at the DuPont Experimental Station
laboratory, near Wilmington, Delaware
, where most polymer
research was done. Carothers was an organic chemist who, in addition to first developing nylon, also helped lay the groundwork for Neoprene
. After receiving his Ph.D., he taught at several universities before he was hired by DuPont to work on fundamental research.
He married Helen Sweetman on February 21, 1936. Carothers had been troubled by periods of mental depression since his youth. Despite his success with nylon, he felt that he had not accomplished much and had run out of ideas. His unhappiness was compounded by the death of his sister, Isobel, and on the evening of April 28, 1937 he checked into a Philadelphia hotel room and committed suicide by drinking a cocktail of lemon juice laced with potassium cyanide
. His daughter, Jane, was born seven months later on November 27, 1937.
, to Ira and Mary Evalina Carothers. He was the oldest of four children. He had one brother and two sisters: John, Isobel and Mary. As a youth, Carothers was fascinated by tools and mechanical devices and spent many hours experimenting. He attended public school in Des Moines, Iowa
, where he was known as a conscientious student. After graduation, and under pressure from his father, Carothers enrolled in the Capital City Commercial College in Des Moines, where his father was Vice-President, completing the accountancy and secretarial curriculum in July 1915.
In September 1915, he entered Tarkio College in Missouri
. Although he initially majored in English, he switched to chemistry under the influence of Arthur Pardee, head of that department. Carothers so excelled in chemistry that before graduation he was made a chemistry instructor and studied for as well as taught the senior course when Pardee left to become chairman of the chemistry department at the University of South Dakota
. He graduated from Tarkio in 1920 at the age of 24 with a bachelor of science degree. Then he went to the University of Illinois for his master of arts degree, which he received in 1921 under the guidance of Professor Carl Marvel
.
During the 1921–22 school year, Carothers held a one-year appointment as a chemistry instructor at the University of South Dakota
. It was at the University of South Dakota that he began his independent research that resulted in an article accepted by the Journal of the American Chemical Society
.
He went back to the University of Illinois to study for his Ph.D. under Roger Adams
. His degree was awarded in 1924. He specialized in organic chemistry and minored in physical chemistry and mathematics. He worked as a research assistant during 1922–1923 and received the Carr Fellowship for 1923–24. This was the most prestigious award offered by the university at that time.
In 1947 Carothers moved to Harvard University
. Again he was an instructor in organic chemistry. James B. Conant
, who became President of Harvard College
in 1933, not of eatss:
In 1927, DuPont decided to fund fundamental, pure research: research not deliberately aimed at the development of a money-making product. Carothers traveled to Wilmington, Delaware
to discuss the possibility of being in charge of organic chemistry at the new DuPont laboratory for fundamental research.
Later in a letter to Wilko Machetanz, his Tarkio roommate, Carothers expanded on his feelings of depression: "I find myself, even now, accepting incalculable benefits proffered out of sheer magnanimity and good will and failing to make even such trivial return as circumstances permit and human feeling and decency demand, out of obtuseness or fear or selfishness or mere indifference and complete lack of feeling."
with a molecular weight of more than 4,200, the mass achieved by Dr. Emil Fischer
, was his primary goal.
By the summer of 1928, Carothers boasted a small staff of Ph.D. chemists and two consultants: Dr. Roger Adams, his thesis advisor, and Dr. Carl Marvel, his instructor of organic chemistry at the University of Illinois. The laboratory where these top scientists worked became known as "Purity Hall". It was discouraging that by the middle of 1929, "Purity Hall" had not produced a polymer with a weight of much over 4,000.
In January 1930, Dr. Elmer K. Bolton became assistant chemical director in the chemical department, and thus, Carothers' immediate boss. Bolton wanted practical results in 1930, and his wish was fulfilled. Bolton asked Carothers to examine the chemistry of an acetylene
polymer with the goal of creating synthetic rubber
. In April 1930 one of Carothers' staff, Dr. Arnold M. Collins, isolated chloroprene
, a liquid which polymerized to produce a solid material that resembled rubber. This product was the first synthetic rubber and is known today as Neoprene
.
with a molecular weight of above 4,000. His efforts were soon met with great success when he produced a synthetic polymer with a molecular weight of about 12,000. The high molecular weight allowed the melted polymer to be stretched out into strings of fiber. Thus was created the first synthetic silk
, described by the chemists as a superpolyester.
Polyesters and polyamides are examples of condensation polymer
s formed by step-growth polymerization
. Carothers worked out the theory of step-growth polymerization and derived the Carothers equation which relates the average degree of polymerization
to the fractional conversion (or yield
) of monomer into polymer. This equation shows that for a high molecular weight, a very high fractional conversion is needed (for step-growth polymers only).
Hill also produced a synthetic fiber that was elastic and strong by combining glycols and diacids and heating under reduced pressure, using a molecular still to remove the last traces of water produced in the condensation reaction. Unfortunately, the fiber produced could not be commercialized because it reverted back to a sticky mass when placed in hot water. Carothers dropped his research on polymers for several years.
Carothers hated the public speaking that was necessary to maintain his high profile. In a letter to Frances Spencer in January 1932, he related, "I did go up to New Haven during the holidays and made a speech at the organic symposium. It was pretty well received but the prospect of having to make it ruined the preceding weeks and it was necessary to resort to considerable amounts of alcohol to quiet my nerves for the occasion. … My nervousness, moroseness and vacillation get worse as time goes on, and the frequent resort to drinking doesn't bring about any permanent improvement. 1932 looks pretty black to me just now."
In 1932, the agreement under which Carothers was hired was modified by Dr. Bolton. "Purity Hall" would now focus on "effecting a closer relationship between the ultimate objectives of our work and the interests of the company." This meant that funds were shifted from pure research to practical research. Carothers did not see himself as a skilled commercial researcher. He proposed that fundamental work be limited to two or three proposals, which would be consistent with DuPont's interests.
s for glycols to produce a type of polymer called a polyamide
. These substances were much more stable than the polyesters formed by using the glycols. The ability of polyamides to form crystalline domains through hydrogen bonding gives them increased mechanical properties. Therefore they might produce a synthetic silk that would be practical for everyday use. His research resulted in the invention of a number of new polyamides. The lab work for this project was conducted by Dr. W.R. Peterson and Dr. Donald Coffman. Later Dr. Gerard Berchet was assigned to this research.
It was during this productive period of research, in the summer of 1934, prior to the eventual invention of nylon, that Carothers disappeared. He did not come into work, and no one knew where he was. He was found in a small psychiatric clinic, Pinel Clinic, near the famous Phipps Clinic associated with Johns Hopkins Hospital
in Baltimore. Apparently, he had become so depressed that he drove to Baltimore to consult a psychiatrist, who put him in the clinic.
Carother's work in linear super-polymers began as an unrestricted foray into the unknown, with no practical objective in mind. But the research was in a new field in chemistry and Du Pont believed that any new chemical breakthrough would likely be of value to the company. In the course of research Carothers obtained some super-polymers that became viscous solids at high temperatures, and the observation was made that filaments could be made from this material if a rod were dipped in the molten polymer and withdrawn. At this discovery the focus of the project shifted to these filaments and `Nylon` was the result.
On February 28, 1935, he produced a half-ounce of a polymer, which was labeled polyamide 6-6. This was the substance that would eventually become Nylon. It was difficult to work with because of its high melting point, but Bolton chose this polyamide as the one to develop commercially. He selected Dr. George Graves to work with Carothers on the project. Eventually Graves supplanted Carothers as the leader of the polyamide project. In addition, dozens of chemists and engineers worked on refining polyamide 6-6 into a viable commercial product.
Soon after, on April 30, 1936, Carothers was elected to the National Academy of Sciences
, a very high honor. Carothers was the first industrial organic chemist to receive this honor. Yet by June 1936, in spite of this honor which validated his contributions to science, Carothers could not shake the depression that prevented him from working. In early June he was admitted involuntarily to the Philadelphia Institute of Pennsylvania Hospital
, a prestigious mental hospital, where his psychiatrist was Dr. Kenneth Appel. One month later he was given permission to leave the institute to go hiking in the Tyrolean Alps with friends. The plan was for him to day hike with Dr. Roger Adams and Dr. John Flack for two weeks. After they left, he stayed on, hiking by himself, without sending word to anyone, even his wife. On September 14, he suddenly appeared at her desk at the Experimental Station. From that point on Carothers was not expected to perform any real work at the Experimental Station. He would often go in and visit. He began living in Whiskey Acres again, at the request of his wife, who did not feel emotionally strong enough to handle his problems.
On January 8, 1937, Carothers' sister Isobel died of pneumonia. Wallace and Helen Carothers traveled to Chicago to attend her funeral and then to Des Moines for her burial. He still traveled to Philadelphia to visit his psychiatrist, Dr. Appel, who told a friend of Carothers that he thought suicide was the likely outcome of Carothers' case.
On April 28, 1937, Carothers went to the Experimental Station to work. The following day he committed suicide in a hotel room in Philadelphia by taking cyanide dissolved in lemon juice, knowing that the ingestion of cyanide in an acidic solution would greatly intensify the speed and effect of the poison. No note was found.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
chemist, inventor and the leader of organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
at DuPont
DuPont
E. I. du Pont de Nemours and Company , commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont was the world's third largest chemical company based on market capitalization and ninth based on revenue in 2009...
, credited with the invention of nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
.
Carothers was a group leader at the DuPont Experimental Station
DuPont Experimental Station
The DuPont Experimental Station is the largest research and development facility of E. I. du Pont de Nemours and Company. Located on the banks of the Brandywine Creek in Wilmington, Delaware, it is home to some of the most important discoveries of the modern chemical industry...
laboratory, near Wilmington, Delaware
Wilmington, Delaware
Wilmington is the largest city in the state of Delaware, United States, and is located at the confluence of the Christina River and Brandywine Creek, near where the Christina flows into the Delaware River. It is the county seat of New Castle County and one of the major cities in the Delaware Valley...
, where most polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
research was done. Carothers was an organic chemist who, in addition to first developing nylon, also helped lay the groundwork for Neoprene
Neoprene
Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...
. After receiving his Ph.D., he taught at several universities before he was hired by DuPont to work on fundamental research.
He married Helen Sweetman on February 21, 1936. Carothers had been troubled by periods of mental depression since his youth. Despite his success with nylon, he felt that he had not accomplished much and had run out of ideas. His unhappiness was compounded by the death of his sister, Isobel, and on the evening of April 28, 1937 he checked into a Philadelphia hotel room and committed suicide by drinking a cocktail of lemon juice laced with potassium cyanide
Potassium cyanide
Potassium cyanide is an inorganic compound with the formula KCN. This colorless crystalline compound, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewelry for chemical gilding and...
. His daughter, Jane, was born seven months later on November 27, 1937.
Early life and education
Carothers was born on April 27, 1896 in Burlington, IowaBurlington, Iowa
Burlington is a city in, and the county seat of Des Moines County, Iowa, United States. The population was 25,663 in the 2010 census, a decline from the 26,839 population in the 2000 census. Burlington is the center of a micropolitan area including West Burlington, Iowa and Middletown, Iowa and...
, to Ira and Mary Evalina Carothers. He was the oldest of four children. He had one brother and two sisters: John, Isobel and Mary. As a youth, Carothers was fascinated by tools and mechanical devices and spent many hours experimenting. He attended public school in Des Moines, Iowa
Des Moines, Iowa
Des Moines is the capital and the most populous city in the US state of Iowa. It is also the county seat of Polk County. A small portion of the city extends into Warren County. It was incorporated on September 22, 1851, as Fort Des Moines which was shortened to "Des Moines" in 1857...
, where he was known as a conscientious student. After graduation, and under pressure from his father, Carothers enrolled in the Capital City Commercial College in Des Moines, where his father was Vice-President, completing the accountancy and secretarial curriculum in July 1915.
In September 1915, he entered Tarkio College in Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
. Although he initially majored in English, he switched to chemistry under the influence of Arthur Pardee, head of that department. Carothers so excelled in chemistry that before graduation he was made a chemistry instructor and studied for as well as taught the senior course when Pardee left to become chairman of the chemistry department at the University of South Dakota
University of South Dakota
The University of South Dakota ', the state’s oldest university, was founded in 1862 and classes began in 1882. Located in Vermillion, South Dakota, United States, USD is home to South Dakota's only medical school and law school. USD is governed by the South Dakota Board of Regents, and its current...
. He graduated from Tarkio in 1920 at the age of 24 with a bachelor of science degree. Then he went to the University of Illinois for his master of arts degree, which he received in 1921 under the guidance of Professor Carl Marvel
Carl Shipp Marvel
Carl Shipp "Speed" Marvel was an American polymer chemist who worked at developing polybenzimidazoles, which are temperature-resistant polymers that are used in the aerospace industry and as a replacement for asbestos.He obtained the nickname "Speed" early on in his career as a chemist from his...
.
During the 1921–22 school year, Carothers held a one-year appointment as a chemistry instructor at the University of South Dakota
University of South Dakota
The University of South Dakota ', the state’s oldest university, was founded in 1862 and classes began in 1882. Located in Vermillion, South Dakota, United States, USD is home to South Dakota's only medical school and law school. USD is governed by the South Dakota Board of Regents, and its current...
. It was at the University of South Dakota that he began his independent research that resulted in an article accepted by the Journal of the American Chemical Society
Journal of the American Chemical Society
The Journal of the American Chemical Society is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the Journal of Analytical and Applied Chemistry and the American Chemical Journal...
.
He went back to the University of Illinois to study for his Ph.D. under Roger Adams
Roger Adams
Roger Adams was an American organic chemist. He is best-known for the eponymous Adams' catalyst, and his work did much to determine the composition of naturally occurring substances such as complex vegetable oils and plant alkaloids...
. His degree was awarded in 1924. He specialized in organic chemistry and minored in physical chemistry and mathematics. He worked as a research assistant during 1922–1923 and received the Carr Fellowship for 1923–24. This was the most prestigious award offered by the university at that time.
Career
After receiving his Ph.D., Carothers stayed at the University of Illinois for two years as an instructor in organic chemistry.In 1947 Carothers moved to Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
. Again he was an instructor in organic chemistry. James B. Conant
James Bryant Conant
James Bryant Conant was a chemist, educational administrator, and government official. As thePresident of Harvard University he reformed it as a research institution.-Biography :...
, who became President of Harvard College
Harvard College
Harvard College, in Cambridge, Massachusetts, is one of two schools within Harvard University granting undergraduate degrees...
in 1933, not of eatss:
"In his research, Dr. Carothers showed even at this time the high degree of originality which marked his later work. He was never content to follow the beaten path or to accept the usual interpretations of organic reactions. His first thinking about polymerizationPolymerizationIn polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
and the structure of substances of high molecular weight began while he was at Harvard."
In 1927, DuPont decided to fund fundamental, pure research: research not deliberately aimed at the development of a money-making product. Carothers traveled to Wilmington, Delaware
Wilmington, Delaware
Wilmington is the largest city in the state of Delaware, United States, and is located at the confluence of the Christina River and Brandywine Creek, near where the Christina flows into the Delaware River. It is the county seat of New Castle County and one of the major cities in the Delaware Valley...
to discuss the possibility of being in charge of organic chemistry at the new DuPont laboratory for fundamental research.
DuPont
The decision to leave academia was difficult for Carothers. At first he refused DuPont's offer of employment, explaining that "I suffer from neurotic spells of diminished capacity which might constitute a much more serious handicap there than here." In spite of this admission, a DuPont executive, Hamilton Bradshaw, traveled to Harvard and convinced Carothers to change his mind. His salary was $500 a month as compared with only $267 at Harvard ($3200 per year).Later in a letter to Wilko Machetanz, his Tarkio roommate, Carothers expanded on his feelings of depression: "I find myself, even now, accepting incalculable benefits proffered out of sheer magnanimity and good will and failing to make even such trivial return as circumstances permit and human feeling and decency demand, out of obtuseness or fear or selfishness or mere indifference and complete lack of feeling."
Neoprene
Carothers began working at the DuPont Experimental Station on February 6, 1928. The synthesis of a polymerPolymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
with a molecular weight of more than 4,200, the mass achieved by Dr. Emil Fischer
Hermann Emil Fischer
Hermann Emil Fischer, Emil Fischer was a German chemist and 1902 recipient of the Nobel Prize in Chemistry. He discovered the Fischer esterification. He developed the Fischer projection, a symbolic way of drawing asymmetric carbon atoms.-Early years:Fischer was born in Euskirchen, near Cologne,...
, was his primary goal.
By the summer of 1928, Carothers boasted a small staff of Ph.D. chemists and two consultants: Dr. Roger Adams, his thesis advisor, and Dr. Carl Marvel, his instructor of organic chemistry at the University of Illinois. The laboratory where these top scientists worked became known as "Purity Hall". It was discouraging that by the middle of 1929, "Purity Hall" had not produced a polymer with a weight of much over 4,000.
In January 1930, Dr. Elmer K. Bolton became assistant chemical director in the chemical department, and thus, Carothers' immediate boss. Bolton wanted practical results in 1930, and his wish was fulfilled. Bolton asked Carothers to examine the chemistry of an acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
polymer with the goal of creating synthetic rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
. In April 1930 one of Carothers' staff, Dr. Arnold M. Collins, isolated chloroprene
Chloroprene
Chloroprene is the common name for the organic compound 2-chlorobuta-1,3-diene, which has the formula CH2=CCl-CH=CH2. This colorless liquid is the monomer for the production of the polymer polychloroprene, a type of synthetic rubber...
, a liquid which polymerized to produce a solid material that resembled rubber. This product was the first synthetic rubber and is known today as Neoprene
Neoprene
Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...
.
Polyesters
In the same year, Dr. Julian Hill, another member of the Carothers team, began work again on attempting to produce a polyesterPolyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
with a molecular weight of above 4,000. His efforts were soon met with great success when he produced a synthetic polymer with a molecular weight of about 12,000. The high molecular weight allowed the melted polymer to be stretched out into strings of fiber. Thus was created the first synthetic silk
Silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
, described by the chemists as a superpolyester.
Polyesters and polyamides are examples of condensation polymer
Condensation polymer
Condensation polymers are any kind of polymers formed through a condensation reaction, releasing small molecules as by-products such as water or methanol, as opposed to addition polymers which involve the reaction of unsaturated monomers...
s formed by step-growth polymerization
Step-growth polymerization
Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally occurring and some synthetic polymers are produced by step-growth...
. Carothers worked out the theory of step-growth polymerization and derived the Carothers equation which relates the average degree of polymerization
Degree of polymerization
The degree of polymerization, or DP, is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule.For a homopolymer, there is only one type of monomeric unit andthe number-average degree of polymerization is given by...
to the fractional conversion (or yield
Yield (chemistry)
In chemistry, yield, also referred to as chemical yield and reaction yield, is the amount of product obtained in a chemical reaction. The absolute yield can be given as the weight in grams or in moles...
) of monomer into polymer. This equation shows that for a high molecular weight, a very high fractional conversion is needed (for step-growth polymers only).
Hill also produced a synthetic fiber that was elastic and strong by combining glycols and diacids and heating under reduced pressure, using a molecular still to remove the last traces of water produced in the condensation reaction. Unfortunately, the fiber produced could not be commercialized because it reverted back to a sticky mass when placed in hot water. Carothers dropped his research on polymers for several years.
Depression
In 1931, Carothers moved into a house in Wilmington, which became known as Whiskey Acres, with three other DuPont scientists. He was no recluse, but his depressive moods often prevented him from enjoying all the activities in which his roommates took part. In a letter to a close friend, Frances Spencer, he said, "There doesn't seem to be much to report concerning my experiences outside of chemistry. I'm living out in the country now with three other bachelors, and they being socially inclined have all gone out in tall hats and white ties, while I after my ancient custom sit sullenly at home." At about this time, Carothers showed Julian Hill that he kept a capsule of cyanide attached to his watch chain.Carothers hated the public speaking that was necessary to maintain his high profile. In a letter to Frances Spencer in January 1932, he related, "I did go up to New Haven during the holidays and made a speech at the organic symposium. It was pretty well received but the prospect of having to make it ruined the preceding weeks and it was necessary to resort to considerable amounts of alcohol to quiet my nerves for the occasion. … My nervousness, moroseness and vacillation get worse as time goes on, and the frequent resort to drinking doesn't bring about any permanent improvement. 1932 looks pretty black to me just now."
In 1932, the agreement under which Carothers was hired was modified by Dr. Bolton. "Purity Hall" would now focus on "effecting a closer relationship between the ultimate objectives of our work and the interests of the company." This meant that funds were shifted from pure research to practical research. Carothers did not see himself as a skilled commercial researcher. He proposed that fundamental work be limited to two or three proposals, which would be consistent with DuPont's interests.
Personal life
Carothers's personal life during this time was busy. He was having an affair with a married woman, Sylvia Moore, who, with her husband filed for divorce in 1933. At the same time, he worried about the financial problems of his parents and planned to bring them to Wilmington. With no thought of the possible emotional ramifications of this move, he bought a house in Arden about ten miles (16 km) from the Experimental Station and moved into it with his parents. He was 37 at the time. Interactions with his parents soon became tense. Carothers was still seeing Sylvia Moore, who was now single, and his parents highly disapproved of this relationship. Finding the tension in the household too wearing, his parents returned to Des Moines in the spring of 1934.Polyamides
In 1934, Carothers turned his attention to fibers again. Now the team substituted diamineAmine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s for glycols to produce a type of polymer called a polyamide
Polyamide
A polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solid-phase synthesis, examples being nylons, aramids,...
. These substances were much more stable than the polyesters formed by using the glycols. The ability of polyamides to form crystalline domains through hydrogen bonding gives them increased mechanical properties. Therefore they might produce a synthetic silk that would be practical for everyday use. His research resulted in the invention of a number of new polyamides. The lab work for this project was conducted by Dr. W.R. Peterson and Dr. Donald Coffman. Later Dr. Gerard Berchet was assigned to this research.
It was during this productive period of research, in the summer of 1934, prior to the eventual invention of nylon, that Carothers disappeared. He did not come into work, and no one knew where he was. He was found in a small psychiatric clinic, Pinel Clinic, near the famous Phipps Clinic associated with Johns Hopkins Hospital
Johns Hopkins Hospital
The Johns Hopkins Hospital is the teaching hospital and biomedical research facility of Johns Hopkins University School of Medicine, located in Baltimore, Maryland . It was founded using money from a bequest by philanthropist Johns Hopkins...
in Baltimore. Apparently, he had become so depressed that he drove to Baltimore to consult a psychiatrist, who put him in the clinic.
Nylon
Shortly after his release from the clinic, Carothers returned to DuPont. Bolton instructed Carothers to work on polyamides.Carother's work in linear super-polymers began as an unrestricted foray into the unknown, with no practical objective in mind. But the research was in a new field in chemistry and Du Pont believed that any new chemical breakthrough would likely be of value to the company. In the course of research Carothers obtained some super-polymers that became viscous solids at high temperatures, and the observation was made that filaments could be made from this material if a rod were dipped in the molten polymer and withdrawn. At this discovery the focus of the project shifted to these filaments and `Nylon` was the result.
On February 28, 1935, he produced a half-ounce of a polymer, which was labeled polyamide 6-6. This was the substance that would eventually become Nylon. It was difficult to work with because of its high melting point, but Bolton chose this polyamide as the one to develop commercially. He selected Dr. George Graves to work with Carothers on the project. Eventually Graves supplanted Carothers as the leader of the polyamide project. In addition, dozens of chemists and engineers worked on refining polyamide 6-6 into a viable commercial product.
Marriage and decline
On February 21, 1936, Carothers married Helen Sweetman, whom he had been dating since 1934. Sweetman worked for DuPont on the preparation of patent applications. She had a bachelors degree in Chemistry.Soon after, on April 30, 1936, Carothers was elected to the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
, a very high honor. Carothers was the first industrial organic chemist to receive this honor. Yet by June 1936, in spite of this honor which validated his contributions to science, Carothers could not shake the depression that prevented him from working. In early June he was admitted involuntarily to the Philadelphia Institute of Pennsylvania Hospital
The Institute of the Pennsylvania Hospital
The Institute of the Pennsylvania Hospital, or Kirkbride's Hospital, was a psychiatric hospital located in Philadelphia, Pennsylvania, that operated from its founding in 1841 until 1997...
, a prestigious mental hospital, where his psychiatrist was Dr. Kenneth Appel. One month later he was given permission to leave the institute to go hiking in the Tyrolean Alps with friends. The plan was for him to day hike with Dr. Roger Adams and Dr. John Flack for two weeks. After they left, he stayed on, hiking by himself, without sending word to anyone, even his wife. On September 14, he suddenly appeared at her desk at the Experimental Station. From that point on Carothers was not expected to perform any real work at the Experimental Station. He would often go in and visit. He began living in Whiskey Acres again, at the request of his wife, who did not feel emotionally strong enough to handle his problems.
On January 8, 1937, Carothers' sister Isobel died of pneumonia. Wallace and Helen Carothers traveled to Chicago to attend her funeral and then to Des Moines for her burial. He still traveled to Philadelphia to visit his psychiatrist, Dr. Appel, who told a friend of Carothers that he thought suicide was the likely outcome of Carothers' case.
On April 28, 1937, Carothers went to the Experimental Station to work. The following day he committed suicide in a hotel room in Philadelphia by taking cyanide dissolved in lemon juice, knowing that the ingestion of cyanide in an acidic solution would greatly intensify the speed and effect of the poison. No note was found.