Stephanie Kwolek

Stephanie Kwolek was a pioneering American chemist who revolutionized materials science.

She spent more than 40 years conducting research at the DuPont company. Kwolek is best known for inventing Kevlar, a high-strength material. This material is a type of aramid, which is a class of polymers known as aromatic polyamides. These polymers are characterized by their ability to form strong, stiff, and flame-resistant fibers. Her work transformed how we protect people and equipment in many different industries.

Kwolek’s discovery of Kevlar began with a search for new industrial materials. In 1964, her research group was looking for a lightweight fiber to replace steel in tires. This was done in anticipation of a potential gasoline shortage. During her research into aramids, she encountered an unusual substance. Most polymer solutions are clear or translucent and have the viscosity of molasses. However, the solution Kwolek prepared was cloudy, turbid, and looked like buttermilk.

She eventually realized this was a liquid crystalline solution.

To understand how Kevlar works, one must look at its molecular structure. The polymer molecules in Kevlar are shaped like long, stiff rods or matchsticks. These are called highly oriented molecules. When the fibers are produced, these rodlike molecules arrange themselves in a very regular pattern. This specific molecular arrangement gives Kevlar its unprecedented stiffness and tensile strength. Kwolek discovered that these fibers could be made even stronger through a process called heat-treating. This process helps the molecules stay in their strong, organized positions.

The process of creating these fibers was not easy. Because the solution was so cloudy, many people thought it would clog the machines. Kwolek was actually denied the use of the spinneret, which is the device used to spin liquid into fiber. She eventually persuaded a technician named Charles Smullen to test her solution. They discovered that the resulting fiber was not only stronger than nylon, but it was also five times stronger than steel by weight. This discovery led to the commercial release of Kevlar.

Kwolek’s career was marked by many significant scientific achievements and honors. She earned her Bachelor of Science degree in chemistry from Carnegie Mellon University in 1946. During her long career at DuPont, she filed a total of 28 patents. She contributed to the development of several famous materials, including Spandex (also known as Lycra), Nomex, and Kapton. In 1974, she was awarded the patent for Kevlar. In 1995, she became the first woman to receive DuPont’s Lavoisier Medal for outstanding technical achievement.

Today, the applications for Kevlar are incredibly diverse. It is used in more than 200 different products around the world. One of its most vital uses is in lightweight body armor for police and military personnel. It is also used in bullet-resistant vests, which are essential for safety. Beyond protection, Kevlar is found in tennis rackets, skis, and parachute lines. It is even used in consumer electronics, such as the unibody of the Motorola Droid RAZR cell phone. You can also find it in heavy-duty items like boat parts, airplane components, and bridge reinforcements.

Beyond her laboratory success, Kwolek was a dedicated advocate for women in STEM. She worked to increase the participation of women in science, technology, engineering, and mathematics. She often spoke about the challenges of working in a male-dominated field. After she retired in 1986, she continued to mentor students and give talks in classrooms. She wanted to show young people that science is a creative and impactful field. Her legacy is honored by the Royal Society of Chemistry through the Stephanie L. Kwolek Award. This award recognizes outstanding contributions to materials chemistry from scientists outside the United Kingdom.