Polyurethanes are polymers made up of long chains, with the base monomer being composed of carbon, hydrogen, oxygen, and nitrogen. There are various types of polyurethanes, with each individual type yielding different properties. Polyurethanes may come in the form of rigid or flexible foams, adhesives, coatings, or as a thermoplastic polyurethane. Overall, polyurethanes have excellent toughness, clarity, low-temperature flexibility, and are biocompatible. Polyurethanes are used in applications such as blood bags, pacemaker leads, body and limb prosthesis, and acetabular cups.