Although the terms "urethane" and "polyurethane" are often used interchangeably, these are two distinctly different compounds.
Urethane is a crystalline compound with the chemical formula C3 H7 NO2. It is an ester of carbonic acid.
Polyurethane is called such because it is composed of multiple, or “poly,” urethane units. The urethane units are joined by a chemical reaction called polymerization.
Urethane is flexible and malleable, making it ideal for objects that have different shapes and forms, and it is used in liquid form. Polyurethane, on the other hand, is stiff and rigid and is ideal for firmer items, with many advantages over natural rubber.
Many insecticides, veterinary medicines and pharmaceuticals contain different amounts of urethane. The compound is also used as a solvent. Some plastics are formed of urethane.
Polyurethane is used for solid materials such as shoes and foams. Some types of polyurethane are also mixed in paints for a long-lasting coating.
Urethane is toxic to small animals. People who take pharmaceuticals with urethane often experience nausea as a side effect. Polyurethane, on the other hand, biodegrades very slowly and generally poses a low toxic risk.