Stephanie Kwolek originally intended to enter the field of medicine, but in the meantime began what she thought would be just a temporary job at DuPont. She found the work so interesting, she decided to stay. Not only is she the inventor of Kevlar, but also of a completely new research field: polymer chemistry.
See the entry about Ms. Kwolek in Wikipedia to learn more about this outstanding woman.
You can see a complete timeline of her life and achievements on Behance.