Polyurethane is a man-made plastic material. It is made from polymers. The fabric mimics the look of rubber latex. But at a fraction of the cost. It is super smooth to touch and shiny. Therefore, polyurethane is often used to create a fetish vibe on clothing and underwear.
Polyurethane is typically laminated onto a cotton or polyester base. Therefore, it is soft to touch on the inside, perfect for underwear. But it is a smooth and shiny rubber look on the outside.