Stephanie Kwolek

Template:Short description Template:Use mdy dates Template:Use American English Template:Infobox scientist Stephanie Louise Kwolek (Template:IPAc-en; July 31, 1923 – June 18, 2014) was an American chemist best known for inventing Kevlar (poly-paraphenylene terephthalamide). Her career at the DuPont company spanned more than 40 years.<ref name="chf"/><ref>Template:US Patent Wholly Aromatic Carbocyclic Polycarbonamide Fiber. Kevlar patent awarded in 1974 to Stephanie Kwolek.</ref>

For her discovery, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement. As of August 2019, she was the only female employee to have received that honor.<ref name="samorodnitsky">Dan Samorodnitsky, "Meet Stephanie Kwolek, the woman who gave us bulletproof vests and yoga pants" Massive Science, July 31, 2019.</ref> In 1995 she became the fourth woman to be added to the National Inventors Hall of Fame.<ref name="UDelaware"/> Kwolek won numerous awards for her work in polymer chemistry, including the National Medal of Technology, the IRI Achievement Award and the Perkin Medal.<ref name="OralHistory"/><ref name="SCI Perkin Medal">Template:Cite web</ref>

Early life and education

Kwolek was one of two children born to Polish immigrant parents in the Pittsburgh suburb of New Kensington, Pennsylvania, in 1923.<ref name="nnbd">Template:Cite web</ref> The grade school she attended was small enough to require her classroom be shared by two different grades, which she found to be an advantage; as Kwolek's love of science grew, she easily outpaced even the older children across the room.<ref name=":0">Template:Cite web</ref> Her father, John Kwolek,<ref name="nnbd" /> died when she was ten years old.<ref name="MIT" /> He was a naturalist by avocation, and Kwolek spent hours with him, as a child, exploring the natural world.<ref name="chf" /> They would spend afternoons together exploring the woods nearby, collecting plants and observing animals that they would later name and characterize in a scrapbook.<ref name=":1" /> She attributed her interest in science to him and an interest in fashion design to her mother Nellie (née Zajdel), who worked as a seamstress. Her mother told her that she was too much of a perfectionist to work a career in fashion, so Stephanie decided to become a physician.<ref name="samorodnitsky" /><ref name="nnbd" /><ref name="MIT" />

In 1946, Stephanie earned a Bachelor of Science degree in chemistry from Margaret Morrison Carnegie College of Carnegie Mellon University. She had planned to become a physician and hoped she could earn enough money from a temporary job in a chemistry-related field to attend medical school.<ref name="MIT" />

DuPont career

Kwolek was offered a position at DuPont's Buffalo, New York, facility in 1946 by William Hale Charch, a future mentor.<ref name="Invent.com">Template:Cite web</ref> During her interview with DuPont, Dr. Charch had said the company would reach out to her in about two weeks to tell her whether she had secured the job. Kwolek asked if they could possibly respond sooner because she had to notify another company if she would accept their offer. Charch then called in his receptionist to dictate Kwolek's offer letter in front of her.<ref>Template:Cite web</ref>

As a chemical company, DuPont was trying to find a petroleum-based polymer fiber that would be lighter and harder-wearing than steel in radial tires. The firm had vacancies, given that many men had been overseas fighting in World War II. DuPont had introduced nylon shortly before the war, and that business boomed and blossomed into several textile applications.

At the same time, the protracted second World War emphasized the need for a lightweight, wearable armor to protect personnel and equipment. As the war raged overseas, soldiers engaged in battle had to do without body armor because there was no material strong enough to stop a rifle bullet but light enough to wear in battle.<ref name=":0" /> Steel was the only armor material available, and its weight limited its use to armored vehicles. Even then, steel could be pierced by specialized armor-piercing ammunition.

Although Kwolek intended to work for DuPont temporarily, in order to raise money for further study, the polymer research she worked on was so interesting and challenging that she decided to drop her plans for medical school and make chemistry a lifetime career.<ref name=OralHistory>Template:Cite book</ref><ref name=Ferguson>Template:Cite book</ref><ref name="Women Scientists in America">Template:Cite book</ref> Her research group moved to Wilmington, Delaware, in 1950.<ref name="Invent.com"/> In 1959, she won a publication award from the American Chemical Society (ACS), the first of many awards. The paper, "The Nylon Rope Trick",<ref name=":1">Template:Cite journal</ref> demonstrated a way of producing nylon in a beaker at room temperature. It is still a common classroom experiment,<ref>Template:Cite news</ref> and the process was extended to high molecular weight polyamides.<ref>Template:Cite journal</ref> In 1985, Kwolek and coworkers patented a method for preparing PBO and PBT polymers.<ref>Template:Cite patent</ref> Because DuPont was at the cutting edge of polymer technology and innovation, Kwolek never outgrew the position and spent her whole career doing research at Dupont. Over her 40-year career, Kwolek would file 28 patents. In addition to Kevlar, she contributed to products such as Spandex (Lycra), Nomex, and Kapton. She continued as a consultant to Dupont after her retirement in 1986, and became the first woman to earn the company’s Lavoisier medal for research in 1995.

She was engaged in the search for new polymers as well as a new condensation process that takes place at lower temperatures around Template:Convert. The melt condensation polymerization process used in preparing nylon, for example, was instead done at more than Template:Convert. The lower-temperature polycondensation processes, which employ very fast-reacting intermediates, make it possible to prepare polymers that cannot be melted and only begin to decompose at temperatures above Template:Convert.

Kevlar

Kwolek is best known for her work during the 1950s and 1960s with aramids, or "aromatic polyamides", a type of polymer that can be made into strong, stiff, and flame-resistant fibres. Her laboratory work in aramids was conducted under the supervision of research fellow Paul W. Morgan, who calculated that the aramids would form stiff fibres owing to the presence of bulky benzene (or "aromatic") rings in their molecular chains but that they would have to be prepared from solution because they melt only at very high temperatures. Kwolek determined the solvents and polymerization conditions suitable for producing poly-m-phenylene isophthalamide, a compound that DuPont released in 1961, as a flame-resistant fibre with the trade name Nomex. She then extended her work into poly-p-benzamide and poly-p-phenylene terephthalamide, which she noted adopted highly regular rodlike molecular arrangements in solution. From these two "liquid crystal polymers" (the first ever prepared), fibres were spun that displayed unprecedented stiffness and tensile strength. The innovative polymer Poly-p-phenylene terephthalamide, as invented by Kwolek, was released commercially under the name Kevlar.<ref name="MIT">Template:Cite web</ref>

In 1964, in anticipation of a gasoline shortage, Kwolek's group began searching for a lightweight yet strong fiber to replace the steel used in tires.<ref name="samorodnitsky"/><ref name="MIT"/> The polymers she had been working with, poly-p-phenylene terephthalate and polybenzamide,<ref name="Bookrags">Template:Cite book</ref> formed liquid crystal while in solution that at the time had to be melt-spun at over Template:Convert, which produced weaker and less stiff fibers. A unique technique in her new projects and the melt-condensation polymerization process was to reduce those temperatures to between the two worlds Template:Convert.<ref name="MIT"/>

As she explained in a 1993 speech:<ref name="PN obit">Template:Cite web</ref>

The solution was unusually (low viscosity), turbid, stir-opalescent and buttermilk in appearance. Conventional polymer solutions are usually clear or translucent and have the viscosity of molasses, more or less. The solution that I prepared looked like a dispersion but was totally filterable through a fine pore filter. This was a liquid crystalline solution, but I did not know it at the time.

This sort of cloudy solution was usually thrown away. Kwolek was denied the use of the spinneret for her solution because it was thought the solution would clog the machine.<ref>Template:Citation</ref> However, Kwolek persuaded technician Charles Smullen, who ran the spinneret, to test her solution. She was amazed to find that the new fiber would not break when nylon typically would. Not only was it stronger than nylon, Kevlar was five times stronger than steel by weight. Both her supervisor and the laboratory director Template:Citation needed understood the significance of her discovery, and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar was introduced.<ref name="MIT"/> Kwolek learned that the fibers could be made even stronger by heat-treating them. The polymer molecules, shaped like rods or matchsticks, are highly oriented, which gives Kevlar its extraordinary strength. Kwolek continued research of thermotropic Kevlar derivatives containing aliphatic and chlorine groups.<ref>Template:Cite journal</ref>

Applications of Kevlar

Kwolek was not much involved in developing practical applications of Kevlar.<ref name="American Heritage">Template:Cite web</ref> Once senior DuPont managers were informed of the discovery, "they immediately assigned a whole group to work on different aspects", she said. Still, Kwolek continued research on Kevlar derivatives.<ref>Template:Cite book</ref> She did not profit from DuPont's products, as she signed over the Kevlar patent to the company.<ref name="Pearce, Jeremy 2014">Template:Cite news</ref>

Kevlar is used in more than 200 applications, including tennis rackets, skis, parachute lines, boats, airplanes, ropes, cables, and bullet-proof vests.<ref name="chf"/> It has been used for car tires, fire fighter boots, hockey sticks, cut-resistant gloves and armored cars. It has also been used for protective building materials like bomb-proof materials, hurricane safe rooms, and bridge reinforcements.<ref name="Pearce, Jeremy 2014" /> During the week of Kwolek's death, the one millionth bullet-resistant vest made with Kevlar was sold.<ref>Template:Cite web</ref> Kevlar is also used to build cell phone cases; Motorola's Droid RAZR has a Kevlar unibody.<ref>Template:Cite web</ref>

Kevlar has gone on to save lives as a lightweight body armor for police and the military; to convey messages across the ocean as a protector of undersea optical-fiber cable; to suspend bridges with super-strong ropes; and to be used in countless more applications from protective clothing for athletes and scientists to canoes, drumheads, and frying pans.Template:Citation needed

Advocacy for women in science and legacy in STEM education

Beyond her scientific achievements, Stephanie Kwolek was a passionate advocate for increasing women's participation in science, technology, engineering, and mathematics (STEM). As one of the few women chemists working at DuPont during the mid-20th century, Kwolek often spoke about the challenges she faced in a male-dominated field and sought to encourage young women to pursue careers in science.

After her retirement, Kwolek volunteered her time to mentor students and deliver talks about chemistry in classrooms across the country. She believed in the importance of hands-on science education and frequently demonstrated experiments such as the "nylon rope trick" to engage students—especially girls—in the wonders of chemistry. Her outreach helped demystify science for young audiences and inspired many to view STEM as a creative and impactful field.

Kwolek also worked with organizations such as the National Academy of Sciences and the National Research Council to promote diversity in scientific disciplines and to advise on science education policy. She served on panels that focused on innovation and the role of women in research, lending her voice to the push for broader inclusion in science and technology professions.

The Royal Society of Chemistry's decision to name a biennial award after her—the Stephanie L. Kwolek Award—underscores her lasting influence not only as a chemist but also as a role model. The award honors outstanding contributions in materials chemistry from scientists working outside the United Kingdom, and its establishment reflects her global impact.

Kwolek's life and career are now taught in many classrooms as part of broader efforts to bring underrepresented figures into STEM curricula. She is frequently included in lists of pioneering women in science and is regarded as an example of perseverance, intellectual rigor, and the importance of representation in research and innovation.

Awards, honors, and legacy

Royal Society of Chemistry – Stephanie L Kwolek Award (2014)

A quote by Stephanie Kwolek, photographed in 2024 inside the Delaware Museum of Nature & Science

For her discovery of Kevlar, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement in 1995, as a "Persistent experimentalist and role model whose discovery of liquid crystalline polyamides led to Kevlar aramid fibers."<ref name=LavoisierDuPont>Template:Cite web</ref><ref name=PRNewswire1995>Template:Cite press release</ref> At the time of her death in 2014, she was still the only female employee to receive that honor.<ref name="BBC News obit">Template:Cite news</ref> Her discovery generated several billion dollars of revenue for DuPont, but she never benefited directly from it financially.<ref name="Pearce, Jeremy 2014"/>

In 1980, Kwolek received the Chemical Pioneer Award from the American Institute of Chemists, and an Award for Creative Invention from the American Chemical Society.<ref name="OralHistory"/> In 1995,<ref name="Invent.com"/><ref name="About.com">Template:Cite web</ref> Kwolek was added to the National Inventors Hall of Fame.<ref name="UDelaware">Template:Cite web</ref> In 1996, she received the National Medal of Technology and the IRI Achievement Award. In 1997, she received the Perkin Medal from the American Chemical Society.<ref name="JCE">Template:Cite journal</ref> In 2003, she was inducted into the National Women's Hall of Fame.<ref name="nnbd"/>

She was awarded honorary degrees by Carnegie Mellon University (2001),<ref name=ObituaryCMU>Template:Cite news</ref> Worcester Polytechnic Institute (1981)<ref name=OralHistory/> and Clarkson University (1997).<ref name=Clarkson>Template:Cite web</ref>

The Royal Society of Chemistry grants a biennial 'Stephanie L Kwolek Award', "to recognise exceptional contributions to the area of materials chemistry from a scientist working outside the UK".<ref name="RSC">Template:Cite web</ref>

Kwolek is featured as one of the Royal Society of Chemistry's 175 Faces of Chemistry.<ref>Template:Cite web</ref>

Later life

During her 40 years as a research scientist, she received 17 patents.<ref>Template:Cite web</ref>

In 1986, Kwolek retired as a research associate for DuPont. Toward the end of her life, she consulted for DuPont and served on both the National Research Council and the National Academy of Sciences.<ref name="samorodnitsky" /><ref>Template:Cite web</ref>

After retirement, Kwolek dedicated herself to science education and outreach. She regularly visited classrooms to demonstrate chemistry experiments and inspire students, especially young girls, to pursue STEM careers.<ref name="samorodnitsky" /> She also remained active in professional organizations, advocating for women in science and offering mentorship to early-career chemists. She continued writing about scientific demonstrations and remained intellectually engaged until her passing.

Kwolek died at the age of 90 in Talleyville, Delaware, on June 18, 2014. She was a practicing Catholic and her funeral was held at St. Joseph on the Brandywine Catholic Church in Greenville, Delaware.<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

See also

• Women in science
• Women in science, engineering and technology

Further reading

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External links

• Stephanie Kwolek at Famous Women Inventors
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• Oral history interview with Stephanie L. Kwolek (1986) from Science History Institute Digital Collections
• Oral history interview with Stephanie L. Kwolek (1998) from Science History Institute Digital Collections
• Stephanie L. Kwolek papers at Hagley Museum and Library
• Stephanie Kwolek photographs and videotapes at Hagley Museum and Library
• Stephanie Kwolek photographs at Hagley Museum and Library