Stephanie L. Kwolek
In a polymer research lab at DuPont, Kwolek discovered the super fiber known as Kevlar.
In 1965 Stephanie Kwolek (1923–2014) looked into a thin, cloudy liquid and discovered something new—something five times stronger than steel. Her research, conducted over a decades-long career at the DuPont Chemical Company, yielded synthetic fibers that would help to define the material world as we know and interact with it today. She was, above all, a creator. She made difficult choices throughout her life that demonstrated her commitment to research in chemistry.
LEARN MORE
Biography is one way of learning about a person. Oral history is another. Spend a few minutes listening to Stephanie Kwolek’s interview archived by the Science History Institute’s Center for Oral History. What do you hear? Has the recording picked up background noises, interesting accents, nervous laughter, or meaningful pauses? What might these tell you about the interview context, who is speaking, or how the speakers feel about the memories being discussed? What do think you can learn about Kwolek from her oral history that is different from the content of this biography?
New Kensington
“I realized early in life that it was a matter of sink or swim,” Kwolek said looking back on her childhood years in New Kensington, then a small town on the outskirts of Pittsburgh, Pennsylvania. She walked several miles to and from her rural elementary school in the shadow of industrial companies like the Aluminum Company of America and Gulf Oil.
Her parents, who were both Polish immigrants, encouraged hobbies and interests that later proved essential to Kwolek’s research career. In his spare time, her father conducted experiments in his garden and designed furniture for the family home. Kwolek spent many hours studying nature alongside him, filling scrapbooks with leaves, wildflowers, seeds, and grasses. Her mother was an excellent seamstress, which provided Kwolek with an early appreciation for textiles and fashion. Both of her parents loved to read.
Tragically, Kwolek’s father died when she was just 10 years old. This was a couple of years before the introduction of Social Security, so her mother had to find a job right away. She went to work manufacturing pots and pans in the Wear-Ever department of the Aluminum Company of America.
Margaret Morrison
There was a strict division between programs for men and women at the Carnegie Institute of Technology (today, Carnegie Mellon University) when Kwolek arrived on campus: women could not enroll, for instance, in the College of Engineering. Instead, they had to enroll in either the Fine Arts College or the Margaret Morrison College for Women. Kwolek chose the latter.
She received excellent mentorship in college and was influenced by two of her chemistry professors—Dr. Clara Miller and Clara Jane Douglas—in particular. Kwolek held a job to support herself on top of her studies, but this did not stand in the way of her academic success. Her honor roll status earned her more scholarships than she could even use. She started working in a biochemistry lab on campus between her second and third years, conducting research on organic compounds and taking part in weekly seminars. She later remembered this as a “delightful and exciting time.” Supervisors recognized the quality of her research and Kwolek was invited to give lectures before visiting European delegates despite her young age.
Though she enjoyed academic research, Kwolek took up work outside the university in her senior year. Gulf Oil paid more than the Carnegie School of Biochemistry and she needed money. Fortunately, she enjoyed the work.
DuPont de Nemours
Kwolek interviewed for jobs with several different companies upon graduation in 1946. Ultimately, she decided to take a position as a chemist in the Textile Fibers Department at DuPont in Buffalo, New York. Not only was she interested in the research they were doing—Wallace Carothers had done pioneering work on nylon with the fundamental research program there not long before—they offered men and women equal starting salaries. She felt like she might have more opportunities at DuPont than elsewhere, and in some respects, she was right.
Kwolek’s job interview with W. Hale Charch, a research director who had figured out how to make cellophane waterproof, was a memorable one. When Charch told her at the end of the interview that he would get back to her in a couple of weeks, Kwolek asked him if he could possibly make a decision sooner because she needed to reply to another offer. Charch called in his secretary and in Kwolek’s presence dictated a letter offering her the position. In later years she suspected that her assertiveness influenced his decision in her favor.
Kwolek’s four years in Buffalo were happy ones. She enjoyed a great deal of independence in her research, which she had plenty of time to do well. On the weekends, she took hiking trips with her colleagues and neighbors. Kwolek had a bustling social life and she met a man she thought she might like to marry. Leaving him to pursue research opportunities in Delaware was a difficult personal choice, one she grieved deeply.
Pioneering Research Laboratory
Kwolek chose to follow DuPont’s Pioneering Research Laboratory from Buffalo to Wilmington, Delaware, in 1950. Leaving her friends and loved ones in Buffalo was not the only sacrifice she made for chemistry. She also gave up her original plans to pursue medicine by committing to the lab, a decision she doubted at first. While she maintained a desire to do work that would be a “benefit to mankind” throughout her life, the research in the Textile Fibers Department was just too interesting to let it go.
At this time, polymer chemistry was not something you learned in school. “We had to learn a lot of chemistry in a hurry on the job,” she later recalled. This leveled the playing field for chemists like Kwolek, who began their research careers with only an undergraduate degree. Advanced understanding of synthetic polymers—macromolecules defined by a long chain-like structure of repeating sub-units—was being cultivated at companies like DuPont, making work experience her most important credential.
Kwolek put that experience to good use. When asked late in life about the highlights of her career, she mentioned two major accomplishments. The first was her discovery of a family of synthetic fibers known for their exceptional strength and stiffness. The most famous of these was commercialized as Kevlar, a material used in some 200 applications including protective vests, boats, airplanes, ropes, cables, bicycle tires, and much more.
LEARN MORE
In the mid-1960s, DuPont employees began searching for a new generation of lightweight fibers of uncommon strength. This involved preparing intermediates, synthesizing aromatic polyamides of high molecular weight, dissolving the polyamides in solvents, and spinning these solutions into fibers. Kwolek discovered that large numbers of the molecules of these rodlike polyamides become lined up in parallel under certain conditions: they formed liquid crystalline solutions that could be spun directly into fibers of very high strength and stiffness. These polyamide solutions were unlike any polymer solutions previously prepared in the laboratory. Though their liquidity was initially a cause of technical concern, to everyone’s surprise, these liquid crystalline solutions spun beautifully.
The second contribution Kwolek emphasized was a process rather than a product. Working collaboratively with other members of her lab, she helped to develop a method for creating polymers at low temperatures. Prior to this work, chemists had been working with the so-called “melt polymerization” process, which required heating solutions to more than 200°C. Though fibers like nylon, which had been produced through this process required very high temperatures to obtain, paradoxically they were not very heat resistant once spun and woven together. Fibers produced through the new condensation process, which basically takes place a room temperature, opened the door to a host of new commercial heat-resistant fibers including “Lycra” spandex fiber, “Kapton” polymide film, “Nomex” paper, and Kevlar.
Recognition
Though Kwolek’s contributions received little recognition at DuPont, she won many awards from professional and cultural organizations outside of the company. She was inducted into the National Inventors Hall of Fame in 1995, received the National Medal of Technology in 1996, and was awarded the Perkin Medal, by the Society of Chemical Industry just one year after that. In 2003 she became a member of the National Women’s Hall of Fame.
By the time these awards were made, Kwolek had been promoted to the position of research associate at DuPont. But it had taken her a long time to rise through the ranks of the company, something she attributed first and foremost to her gender. “I realized,” she said,
In adulthood, as in youth, Kwolek’s “sink or swim” mentality helped her do exceptional work. One of her most cited papers ended up being a piece for the Journal of Chemical Education, a description of a classroom demonstration of the polymerization process under everyday conditions. This “Nylon Rope Trick” has been done countless times—at World’s Fairs, in clubs, and for student groups around the country. Though she never taught chemistry at a university, she supported future generations through her participation in science education programs and her mentorship of other women in science.
Glossary of Terms
Polymer
A large molecule made up of small chaining subunits; these can be natural (e.g. DNA, proteins, cellulose) or synthetic (e.g. plastics, nylon, polyester).
Back to top
Further Reading
Hintz, Eric S. American Independent Inventors in an Era of Corporate R&D. Cambridge, MA: MIT Press, 2021.
Morgan, Paul W. and Stephanie L. Kwolek. “The Nylon Rope Trick: Demonstration of Condensation Polymerization.” Journal of Chemical Education 36 (1959): 182–184.
Rasmussen, Seth C. “From Polymer to Macromolecule: Origins and Historic Evolution of Polymer Terminology.” Bulletin for the History of Chemistry 45 (2020): 91–100.
Support
Support for this biography was made possible by the Wyncote Foundation.
You might also like
VIDEO
The Life and Achievements of Chemist Stephanie Kwolek, Inventor of Kevlar
Watch this PBS News Weekend “Hidden Histories” episode, which features resources from the Institute.
DIGITAL COLLECTIONS
Women & Science Collection
Materials related to notable women scientists as well as images of women working in a variety of laboratory and industrial settings.
DISTILLATIONS MAGAZINE
Nylon: A Revolution in Textiles
The invention of nylon in 1938 promised sleekness and practicality for women and soon ushered in a textile revolution for consumers and the military alike.
