Stephanie Louise Kwolek (/ˈkwoʊlɛk/; July 31, 1923 – June 18, 2014) was a Polish-American chemist best known for inventing Kevlar (poly-paraphenylene terephthalamide).

[1] They would spend afternoons together exploring the woods nearby, collecting plants and observing animals that they would later name and characterize in a scrapbook Kwolek kept, as a child.

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.

[9] Kwolek was offered a position at DuPont's Buffalo, New York, facility in 1946 by William Hale Charch, a future mentor.

[12] 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.

At the same time, the protracted second World War emphasized the need for a lightweight, wearable armor to protect personnel and equipment.

At DuPont, 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.

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 400 °C (752 °F).

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.

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.

[9] 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.

[3][9] The polymers she had been working with, poly-p-phenylene terephthalate and polybenzamide,[18] 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.

Both her supervisor and the laboratory director [citation needed]understood the significance of her discovery, and a new field of polymer chemistry quickly arose.

[24] Kevlar is used in more than 200 applications, including tennis rackets, skis, parachute lines, boats, airplanes, ropes, cables, and bullet-proof vests.

[26] 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.

[29] Her discovery generated several billion dollars of revenue for DuPont, being her employer at the time, but she never benefited directly from it financially.