Stephanie Kwolek

Stephanie Louise Kwolek (July 31, 1923 – June 18, 2014) was an American chemist, whose career at the DuPont company spanned over forty years. She is best known for inventing the first of a family of synthetic fibers of exceptional strength and stiffness: poly-paraphenylene terephthalamide—better known as Kevlar. For her discovery, Kwolek was awarded the DuPont company's Lavoisier Medal for outstanding technical achievement. As of February 2015, she was the only female employee to have received that honor. In 1995 she became the fourth woman to be added to the National Inventors Hall of Fame. Kwolek won numerous awards for her work in polymer chemistry, including the National Medal of Technology, the IRI Achievement Award and the Perkin Medal.

Kwolek was born to Polish immigrant parents in the Pittsburgh suburb of New Kensington, Pennsylvania, in 1923. Her father, John Kwolek (Polish: Jan Chwałek), died when she was ten years old. He was a naturalist by avocation, and Kwolek spent hours with him, as a child, exploring the natural world. She attributed her interest in science to him and an interest in fashion to her mother, Nellie (Zajdel) Kwolek.

In 1946, Kwolek earned a Bachelor of Science degree with a major in chemistry from Margaret Morrison Carnegie College of Carnegie Mellon University. She had planned to become a doctor and hoped she could earn enough money from a temporary job in a chemistry-related field to attend medical school.

In 1946, Hale Charch, a future mentor to Kwolek, offered her a position at DuPont's Buffalo, New York, facility. Charch had initially told Kwolek that he would contact her within two weeks, but after Kwolek said she had to answer another job offer and insisted on a faster reply, Charch immediately offered her the position. She reportedly got her job because of the amount of men that were overseas at the time for World War II. She only kept her job after the war because of her extensive research on polymers. While Kwolek initially only intended to work for DuPont temporarily, she found the work interesting and decided to stay rather than pursuing a medical career, moving to Wilmington, Delaware, in 1950 to continue to work for DuPont. After about nine years with the company, she created Kevlar. In 1959, she won the first of many awards, a publication award from the American Chemical Society (ACS). The paper, The Nylon Rope Trick, demonstrated a way of producing nylon in a beaker at room temperature. It is still the basis of a common classroom experiment.

Kevlar

While working for DuPont, Kwolek invented Kevlar. In 1964, in anticipation of a gasoline shortage, her group began searching for a lightweight yet strong fiber to be used in tires. The polymers she had been working with at the time, poly-p-phenylene terephthalate and polybenzamide, formed liquid crystal while in solution that at the time had to be melt-spun at over 200 °C (392 °F), 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 0–40 °C (32–104 °F).

As she later explained in a 1993 speech:

“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 usually was thrown away. 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 understood the significance of her discovery, and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar was introduced. 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.

Applications of Kevlar

Kwolek was not very involved in developing practical applications of Kevlar. Once senior DuPont managers were informed of the discovery, they immediately assigned a whole group to work on different aspects," she said. She also did not profit from DuPont's products, as she signed over the Kevlar patent to the company.

Kevlar is used as a material in more than 200 applications, including tennis rackets, skis, boats, airplanes, ropes, cables, tires, and bullet-proof vests. It has been used for car tires, fire fighter boots, hockey sticks, cut-resistant gloves, and even armored cars. It has also been used for protective building materials like bomb proof materials, hurricane safe rooms, and overtaxed bridge reinforcements. During the week of Kwolek's death, the one millionth bullet-resistant vest made with Kevlar was sold. Kevlar is also used to build cellular telephones; Motorola's Droid RAZR has a Kevlar unibody.

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." At the time of her death in 2014, she was still the only female employee to receive that honor. Her discovery generated several billion dollars of revenue for DuPont, being her employer at the time, but she never benefited directly from it financially.

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. In 1995, Kwolek became the fourth woman to be added to the National Inventors Hall of Fame. 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. In 2003, she was added to the National Women's Hall of Fame.

She has been awarded honorary degrees by Carnegie Mellon University (2001), Worcester Polytechnic Institute (1981) and Clarkson University (1997).

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

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".

Kwolek is featured as one of the Royal Society of Chemistry 175 Faces of Chemistry.

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. During her 40 years as a research scientist, she filed and received either 17 or 28 patents.

After she retired she became heavily involved in trying to introduce young children, specifically girls, to scientific fields. She often tutored students in chemistry. She has also invented and wrote about numerous classroom demonstrations that are still used in schools today, such as the Nylon Rope Trick.

Kwolek died at the age of 90 on June 18, 2014.