Polyurethane and polyurea biomaterials for use in medical devices

This invention relates to medical devices that include polyurethane and polyurea biomaterials, particularly elastomers, containing sacrificial moieties (e.g., sulfur-containing moieties) that preferentially oxidize relative to other moieties in the polymer. A medical device comprising a biomaterial formed from a polymer comprising urethane groups, urea groups, or combinations thereof, and sacrificial moieties that preferentially oxidize relative to other moieties in the polymer.