Photo by Michael Branscom
In 1965, Stephanie Kwolek made an unexpected discovery that led to the creation of synthetic fibers so strong, not even steel bullets could penetrate them. During her analysis of long molecule chains at low temperatures, Kwolek observed how polyamide molecules line up to form liquid crystalline polymer solutions of exceptional strength and stiffness. That discovery made way for Kwolek’s invention of industrial fibers that today protect and save thousands of lives. Most notable among these is Kevlar®, a heat-resistant material that’s five times stronger than steel, but lighter than fiberglass. Today, Kevlar® is used in hundreds of products, including bulletproof vests, spacecrafts, helmets, tennis racquets, tires, and protective gloves.
Born in New Kensington, PA, Kwolek developed a love of fabrics and sewing from her mother, a homemaker. She also had a strong interest in teaching, chemistry, and especially medicine. After graduating from Margaret Morrison Carnegie College in 1946 with a degree in chemistry, Kwolek applied for a position as a chemist with the DuPont Company, though she still had her eye on medical school.
Fond of the polymer research at DuPont, she abandoned her plans for medical school to become a lifetime chemist. Kwolek specialized in developing low-temperature processes for finding petroleum-based synthetic fibers of incredible strength and rigidity. Assigned to finding the next generation of fibers that could withstand extreme conditions, Kwolek’s work involved preparing intermediates, synthesizing aromatic polyamides of high molecular weight, dissolving the polyamides in solvents, and spinning these solutions into fibers.
Unexpectedly, she discovered that under certain conditions, large numbers of polyamide molecules line up in parallel to form cloudy liquid crystalline solutions. Most researchers would have rejected the solution because it was fluid and cloudy rather than viscous and clear. But Kwolek took a chance and spun the solution into fibers more strong and stiff than had ever been created. This breakthrough opened up the possibilities for a host of new products resistant to tears, bullets, extreme temperatures, and other conditions.
Stephanie Kwolek headed polymer research at DuPont's Pioneering Lab until her retirement in 1986. She has received many awards for her achievements, including induction into the National Inventors Hall of Fame in 1994, the National Medal of Technology (1999), and the Perkin Medal – all rare honors for women. She has served as a mentor for other women scientists and participated in programs that introduce young children to science.